Chronic kidney disease of non-traditional origin in Mesoamerica: a disease primarily driven by occupational heat stress

International prevalence patterns of low eGFR in adults aged 18-60 without traditional risk factors from a population-based cross-sectional disadvantaged populations eGFR epidemiology (DEGREE) study

The disadvantaged populations eGFR (estimated glomerular filtration rate) epidemiology (DEGREE) study was designed to gain insight into the burden of chronic kidney disease (CKD) of undetermined cause (CKDu) using standard protocols to estimate the general-population prevalence of low eGFR internationally. Therefore, we estimated the age-standardized prevalence of eGFR under 60 ml/min per 1.73m2 in adults aged 18-60, excluding participants with commonly known causes of CKD; an ACR (albumin/creatinine ratio) over 300 mg/g or equivalent, or self-reported or measured (HT) hypertension or (DM) diabetes mellitus, stratified by sex and location. We included population-representative surveys conducted around the world that were either designed to estimate CKDu burden or were re-analyses of large surveys. There were 60,964 participants from 43 areas across 14 countries, with data collected 2007- 2023. The highest prevalence was seen in rural men in Uddanam, India (14%) and Northwest Nicaragua (14%). Prevalence above 5% was generally only observed in rural men, with exceptions for rural women in Ecuador (6%) and parts of Uddanam (6%‒8%), and for urban men in Leon, Nicaragua (7%). Outside of Central America and South Asia, prevalence was below 2%. Our observations represent the first attempts to estimate the prevalence of eGFR under 60 without commonly known causes of CKD around the world, as an estimate of CKDu burden, and provide a starting point for global monitoring. It is not yet clear what drives the differences, but available evidence supports a high general-population burden of CKDu in multiple areas within Central America and South Asia, although the possibility that unidentified clusters of disease may exist elsewhere cannot be excluded.

Occupational exposure to respirable and inhalable dust and its components in a Nicaraguan sugarcane plantation

OBJECTIVE

To assess personal exposure to respirable and inhalable dust and its components endotoxin, black carbon and crystalline silica among sugarcane workers in Nicaragua.

METHODS

Individual exposures to respirable (measurements=98) and inhalable (measurements=36) dust were collected in January and March 2020, with the month of March generally being hotter and less humid. Respirable dust and its components black carbon and crystalline silica, as well as inhalable dust and its component endotoxin, were personally measured. Linear mixed models were used to identify the determinants of occupational dust exposure considering different job tasks and meteorological conditions.

RESULTS

Respirable dust and black carbon concentrations were higher in March among burned cane cutters compared with the other job groups (respirable dust geometric mean (GM)=1.9 mg m-3; black carbon GM=13.7 µg m-3), with considerably lower levels in January (respirable dust GM=0.2 mg m-3; black carbon GM=3.4 µg m-3). Almost all respirable crystalline silica measurements were below the limit of detection, except for four measurements, which ranged from 8 µg m-³ to 15 µg m-³. Seed cutters (GM=3.1 mg m-3) and weeders (GM=2.5 mg m-3) had the highest exposure to inhalable dust, while endotoxin concentrations were higher among seed cutters (GM=100 EU m-3) and burned cane cutters (GM=63 EU m-3) than the other work groups.

CONCLUSIONS

Overall, exposure levels to the assessed agents varied across work groups, with higher levels observed among burned cane and seed cutters.

Using environmental and exercise physiology to address gender inequalities in climate change and occupational health research

Climate change is a health-risk and health-inequity multiplier with excessive heat exposure a direct climate change impact already affecting the health and livelihood of billions globally. Women face greater risks and burdens from climate change impacts. Biological sex may or may not influence an individual's thermoregulatory capacity, heat tolerance or heat susceptibility. However at a population level, sex differences in physiological characteristics (anthropometrics, aerobic capacity, etc.) likely affect thermoregulatory capacity. Still, gender appears to play the most significant role in heat exposure and resulting health impacts. For climate change resilience and adaptation strategies to be effective, public health and occupational guidance/governance must be based on comprehensive and representative evidence. The current dearth of empirical evidence on how excessive heat exposure affects women prohibits this. Environmental and exercise physiology can help address this lack of empirical evidence by adhering to inclusive research guidelines. This paper is based on a symposium presentation given at Physiology 2023 in Harrogate, UK. Using a multi-year cohort study on industrial agricultural workers (the Adelante Initiative) as a case study, this review discusses the role of environmental and exercise physiology in generating inclusive research and evidence to inform occupational and public health guidance/governance for climate change resilience and adaptation, specifically heat exposure.

Labour activity and occupational factors associated with kidney function deterioration among workers of the sugarcane industry in Peru

OBJECTIVE

This study compares field workers exposed to occupational conditions with non-field workers to determine the worsening of renal function (eGFR) in workers in the sugar industry.

METHODS

The baseline examination occurred from September to December 2021 in Centro Poblado San Jacinto, Peru, involving 372 men aged 18-60. We compared kidney function between 219 field workers (cane cutters, seed cutters, and seeders) exposed to high heat stress and 153 non-field workers (factory and administrative) with low/no heat stress exposure. Exclusions included participants with high blood pressure, diabetes, and chronic kidney disease. We collected data on CKD risk factors, sociodemographic information, work history, and lifestyle. Measurements included height, weight, blood pressure, serum creatinine, urine analysis, and ambient temperature. The outcome was eGFR <90 ml/min/1.73 m2 and heat-related symptoms.

RESULTS

Field workers reported lower fluid intake (mean 2.7 L) during long shifts with few breaks, while non-field workers had higher rates of alcohol and tobacco use. Field workers had higher serum creatinine (mean 0.84 vs 0.70 mg/dL) and lower eGFR (mean 112 vs 105 ml/min/1.73 m2, p < 0.001), especially among burned cane cutters. Field workers were twice as likely to have reduced kidney function (PR: 1.82, 95% CI: 1.00-3.34), were more frequently dehydrated, and reported more symptoms like muscular weakness, cramps, and exhaustion.

CONCLUSION

We found significantly lower kidney function among field workers, particularly seed and cane cutters. These findings emphasize the need for targeted interventions to protect the renal health.

Heat-induced kidney disease: Understanding the impact

Research on Mesoamerican Nephropathy, chronic kidney disease of unknown cause and chronic kidney disease of nontraditional cause has been going on for more than 20 years. Thousands of manual workers, especially in agriculture, are affected. The disease has been reported in different countries and regions, not only from heat-stressed sugarcane cutters in Central America but also from other occupational groups with strenuous work in hot environments. The cause of this disease is still debated. A multitude of causative factors have been suggested, including agrochemicals, water quality, infections, and heavy metals. The evidence that heat stress is the major cause of kidney disease is convincing, whereas the support for alternative causes is weak. Associations between exposure and kidney damage are strong, consistent, and specific, occur after acute and chronic exposure, display dose-effect and dose-response relationships, are plausible, and coherent. Improving working conditions by providing hydration, rest, and shade to heat-stress-exposed workers is beneficial. Continued global warming will increase the number of people at risk for dangerous heat exposure and kidney disease.

International prevalence patterns of low eGFR in adults aged 18-60 without traditional risk factors from population-based cross-sectional studies: a disadvantaged populations eGFR epidemiology (DEGREE) study

The disadvantaged populations eGFR (estimated glomerular filtration rate) epidemiology (DEGREE) study was designed to gain insight into the burden of chronic kidney disease (CKD) of undetermined cause (CKDu) using standard protocols to estimate the general-population prevalence of low eGFR internationally. We estimated the age-standardised prevalence of eGFR<60ml/min/1.73m2 in adults aged 18-60, excluding participants with commonly known causes of CKD, i.e., ACR>300mg/g or equivalent, or self-reported or measured hypertension or diabetes (eGFR<60[absent HT,DM,high ACR]), and stratified by sex and location. We included population-representative surveys conducted around the world that were either designed to estimate CKDu burden or were re-analyses of large surveys. There were 60 964 participants from 43 areas across 14 countries, with data collected during 2007-2023. The highest prevalence was seen in rural men in Uddanam, India (14%) and Northwest Nicaragua (14%). Prevalence above 5% was generally only observed in rural men, with exceptions for rural women in Ecuador (6%) and parts of Uddanam (6-8%), and for urban men in Leon, Nicaragua (7%). Outside of Central America and South Asia, prevalence was below 2%. These observations represent the first attempts to estimate the prevalence of eGFR<60[absent HT,DM,high ACR] around the world, as an estimate of CKDu burden, and provide a starting point for global monitoring. It is not yet clear what drives the differences, but available evidence to date supports a high general-population burden of CKDu in multiple areas within Central America and South Asia, although the possibility that unidentified clusters of disease may exist elsewhere cannot be excluded.

The work-recovery cycle of kidney strain and inflammation in sugarcane workers following repeat heat exposure at work and at home

PURPOSE

To examine heat exposure at work and home and the work-recovery cycle and temporal variation of kidney strain, muscle injury and inflammation biomarkers in sugarcane workers.

METHODS

20 male sugarcane workers (age: 33 ± 7 years) with a workplace Rest.Shade.Hydration (RSH) intervention were observed over 4 days, at the end (18 h post-shift recovery) and beginning of a work week (42 h post-shift recovery). Measures included work intensity (heart rate), gastro-intestinal temperature, estimated body core temperature (using heart rate), fluid consumption, pre- and post-work blood and urine samples, physical activity (accelerometery) away from work, plus ambient heat exposure at work and home.

RESULTS

On workdays, workers awakened at approx. 02:40 after 5 h sleep in ~ 30 °C. Across work shifts, daily average WBGT ranged from 26 to 29 °C (cooler than normal) and average workload intensity ranged from 55 to 58%HRmax. Workers reported consuming ~ 8 L of water and ~ 4 × 300 mL bags of electrolyte fluid each day. Serum creatinine, cystatin C and creatine phosphokinase markedly increased post-work and decreased during recovery; serum potassium did the opposite (all p < 0.01). Biomarker concentration changes were similar between recovery periods (18 h vs. 42 h; all p > 0.27). C-reactive protein was the highest at the end of the work week (p = 0.01).

CONCLUSION

Despite RSH intervention, cross-shift kidney strain was marked (recovering overnight) and systemic inflammation increased over the work week. Thus, biomonitoring of kidney function in occupational populations should be performed before a work shift at any point in the work week. This is essential knowledge for field studies and surveillance.

Longitudinal Renal Function Degradation Among Florida Agricultural Workers

OBJECTIVE

This longitudinal study evaluated renal function and acute kidney injury (AKI) over time in US agricultural workers.

METHODS

We followed Florida agricultural workers from January 2020 to August 2022, collecting blood and urine preworkday and postworkday during five visits.

RESULTS

Preworkday estimated glomerular filtration rate function in all participants was lower in summers but relatively consistent over time. In participants who worked almost exclusively in fernery operations (piece-rate compensation), we observed a high incidence of postworkday AKI in 2020 (21%) that increased to 43% by the end of the study. In comparison, 11% of nursery workers (hourly compensation) had AKI, and this rate was fairly stable.

CONCLUSION

AKI risk over time differs according to the type of agricultural work. Piece rate workers who are incentivized to forgo rest breaks and hydration to earn higher wages demonstrate steadily increasing rates of AKI.

Nourishing Physical Productivity and Performance On a Warming Planet - Challenges and Nutritional Strategies to Mitigate Exertional Heat Stress

PURPOSE OF REVIEW: Climate change is predicted to increase the frequency and severity of exposure to hot environments. This can impair health, physical performance, and productivity for active individuals in occupational and athletic settings. This review summarizes current knowledge and recent advancements in nutritional strategies to minimize the impact of exertional-heat stress (EHS). RECENT FINDINGS: Hydration strategies limiting body mass loss to < 3% during EHS are performance-beneficial in weight-supported activities, although evidence regarding smaller fluid deficits (< 2% body mass loss) and weight-dependent activities is less clear due to a lack of well-designed studies with adequate blinding. Sodium replacement requirements during EHS depends on both sweat losses and the extent of fluid replacement, with quantified sodium replacement only necessary once fluid replacement > 60-80% of losses. Ice ingestion lowers core temperature and may improve thermal comfort and performance outcomes when consumed before, but less so during activity. Prevention and management of gastrointestinal disturbances during EHS should focus on high carbohydrate but low FODMAP availability before and during exercise, frequent provision of carbohydrate and/or protein during exercise, adequate hydration, and body temperature regulation. Evidence for these approaches is lacking in occupational settings. Acute kidney injury is a potential concern resulting from inadequate fluid replacement during and post-EHS, and emerging evidence suggests that repeated exposures may increase the risk of developing chronic kidney disease. Nutritional strategies can help regulate hydration, body temperature, and gastrointestinal status during EHS. Doing so minimizes the impact of EHS on health and safety and optimizes productivity and performance outcomes on a warming planet.

Admixture Mapping of Chronic Kidney Disease and Risk Factors in Hispanic/Latino Individuals From Central America Country of Origin

BACKGROUND

Chronic kidney disease (CKD) is highly prevalent in Central America, and genetic factors may contribute to CKD risk. To understand the influences of genetic admixture on CKD susceptibility, we conducted an admixture mapping screening of CKD traits and risk factors in US Hispanic and Latino individuals from Central America country of origin.

METHODS

We analyzed 1023 participants of HCHS/SOL (Hispanic Community Health Study/Study of Latinos) who reported 4 grandparents originating from the same Central America country. Ancestry admixture findings were validated on 8191 African Americans from WHI (Women's Health Initiative), 3141 American Indians from SHS (Strong Heart Study), and over 1.1 million European individuals from a multistudy meta-analysis.

RESULTS

We identified 3 novel genomic regions for albuminuria (chromosome 14q24.2), CKD (chromosome 6q25.3), and type 2 diabetes (chromosome 3q22.2). The 14q24.2 locus driven by a Native American ancestry had a protective effect on albuminuria and consisted of 2 nearby regions spanning the RGS6 gene. Variants at this locus were validated in American Indians. The 6q25.3 African ancestry-derived locus, encompassing the ARID1B gene, was associated with increased risk for CKD and replicated in African Americans through admixture mapping. The European ancestry type 2 diabetes locus at 3q22.2, encompassing the EPHB1 and KY genes, was validated in European individuals through variant association.

CONCLUSIONS

US Hispanic/Latino populations are culturally and genetically diverse. This study focusing on Central America grandparent country of origin provides new loci discovery and insights into the ancestry-of-origin influences on CKD and risk factors in US Hispanic and Latino individuals.

Lead exposure by E-waste disposal and recycling in Agbogbloshie, Ghana

BACKGROUND

Agbogbloshie in Ghana is the world's biggest dumpsite for the informal recycling of electronic waste (e-waste). E-waste is dismantled by rudimentary methods without personal or environmental protection. Workers and occupants are exposed to lead. There are no data so far about the extent and the consequences. We therefore analyzed blood lead levels (BLL) and creatinine levels (CL).

METHODS

Full blood samples and basic data (i.e. age, job, length of stay) were collected from dumpsite volunteers. BLL were measured by atomic absorption spectrometry; CL were assessed using the standard clinical laboratory procedures of Aachen Technical University. European BLL reference values were used as Ghana lacks its own. Statistical analysis was by non-parametric tests (Mann-Whitney U test), with p < 0.05.

RESULTS

Participants of both sexes (n = 327; 12-68 years; median age 23 years) were assessed. Most workers were aged <30 years. The collective's BLL was in pathological range for 77.7%; 14% had a BLL >10.0 μg/dl with symptoms consistent with high lead exposure including severe (6.5%) and intermediate (39%) renal disorder. BLL above 15.0 μg/dl were found in 5.9% of all workers which is the German threshold for those working with lead. Elevated CL in a pathological range were found in 254 participants. This is problematic as 75% of the lead entering the body is excreted via urine.

CONCLUSION

Most of our volunteers had pathological BLL and CL. Preventive strategies are necessary to reduce health risks, particularly for vulnerable populations (i.e. children, pregnant women).

Occupational risks associated with chronic kidney disease of non-traditional origin (CKDnt) in Brazil: it is time to dig deeper into a neglected problem

In the past decades, an epidemic of chronic kidney disease (CKD) has been associated with environmental and occupational factors (heat stress from high workloads in hot temperatures and exposure to chemicals, such as pesticides and metals), which has been termed CKD of non-traditional origin (CKDnt). This descriptive review aims to present recent evidence about heat stress, pesticides, and metals as possible causes of CKDnt and provide an overview of the related Brazilian regulation, enforcement, and health surveillance strategies. Brazilian workers are commonly exposed to extreme heat conditions and other CKDnt risk factors, including increasing exposure to pesticides and metals. Furthermore, there is a lack of adequate regulation (and enforcement), public policies, and strategies to protect the kidney health of workers, considering the main risk factors. CKDnt is likely to be a significant cause of CKD in Brazil, since CKD's etiology is unknown in many patients and several conditions for its development are present in the country. Further epidemiological studies may be conducted to explore causal associations and estimate the impact of heat, pesticides, and metals on CKDnt in Brazil. Moreover, public policies should prioritize reducing workers´ exposure and promoting their health and safety.

Association Between Acute Kidney Injury Hospital Visits and Environmental Heat Stress at a Nicaraguan Sugarcane Plantation

BACKGROUND

Mesoamerican sugarcane cutters are at a high risk of chronic kidney disease of non-traditional origin, a disease likely linked to heat-related acute kidney injury (AKI). Studies in general populations have described a positive association between high environmental temperatures and clinically assessed kidney outcomes, but there are no studies in occupational settings.

METHOD

We accessed routine records of clinically diagnosed AKI (AKI-CD) and wet bulb globe temperatures (WBGT) at a large Nicaraguan sugarcane plantation and modeled the relationship between these using negative binomial regression. A rest-shade-hydration intervention was gradually enhanced during the study period, and efforts were made to increase the referral of workers with suspected AKI to healthcare.

RESULTS

Each 1°C WBGT was associated with an 18% (95% confidence interval [CI]: [4, 33%]) higher AKI-CD rate on the same day and a 14% (95% CI [-5, 37%]) higher rate over a week. AKI-CD rates and severity, and time between symptoms onset and diagnosis decreased during the study period, that is, with increasing rest-shade-hydration intervention. Symptoms and biochemical signs of systemic inflammation were common among AKI-CD cases.

DISCUSSION

Occupational heat stress, resulting from heavy work in environmental heat, was associated with a higher rate of clinically diagnosed AKI in a population at risk of CKDnt. Promoting rest-shade-hydration may have contributed to reducing AKI rates during the study period. Occupational health and safety personnel have key roles to play in enforcing rest, shade, and hydration practices, referring workers with suspected AKI to healthcare as well as collecting and analyzing the data needed to support workplace heat stress interventions.

Decreasing incidence of hospital diagnosed CKD/CKDu in North Central Province of Sri Lanka: is it related to provision of drinking water reverse osmosis plants?

BACKGROUND

We assessed the possible impact of provision of reverse osmosis (RO) water on the incidence of hospital diagnosed CKD/CKDu in North Central Province (NCP) of Sri Lanka.

METHODS

An ecological study was conducted on data from 2010-2020 on the incidence of hospital diagnosed CKD/CKDu, CKD/CKDu screening and provision of drinking water RO plants in NCP. Analysis was conducted using descriptive statistics, ANOVA and chi-square test.

RESULTS

The annual incidence of hospital diagnosed CKD/CKDu (per 100 000 population) in 2010-2013, 2014-2016 and 2017-2020 periods in Anuradhapura district were 129.07, 331.06 and 185.57 (p = 0.002) while in Polonnaruwa district these were 149.29, 326.12 and 296.73 (p = 0.04) respectively. In NCP provision of RO plants commenced after 2011 and the decline in the incidence of hospital diagnosed CKD/CKDu was seen in 25 of the 29 Divisional Secretary Divisions when more than 20% of the families received access to drinking RO water projects.

CONCLUSIONS

The annual incidence of hospital diagnosed CKD/CKDu increased in NCP from 2010 to 2016 and continuously decreased thereafter. Continuous declining of CKD/CKDu incidence was seen after more than 20% of the families received access to drinking water RO plants.

Failing kidneys: Hotspots, blind spots and biopolitics of indifference

Chronic kidney disease of non-traditional cause (CKDnt) is commonly associated with monocropping agriculture, heat stress and impoverished working conditions, referred to as CKDnt "hotspots." The condition is also emerging in various sites of environmental contamination, raising questions as to whether multiple variants of the condition exist as a result of different ecologies and different human-environment interactions. This paper examines the emergence of CKDnt around Lake Chapala in Mexico, where we document local efforts to gain recognition and reparation for CKDnt. We follow the ways patients, families and activists have mobilized specific and interlocking infrastructural failures to enact complaint and confront state inaction and neglect of their bodies, communities, and environments. Though their labors have formally achieved little, we discuss how they make visible a biopolitics of indifference, one bound to the production of structural "blindspots."

Impacts of climate change on occupational health indicators in the three climatic regions of Iran

Climate change has increased the exposure risk of workers to occupational health risk factors and diseases. This study aims to investigate the impacts of climate change on the occupational health indicators at the workplaces in Iran. This study was conducted during 2021 in three climatic regions of Iran. Required data was collected from Health Deputies of Medical Universities and Iran Meteorological Organization. Stepwise linear regression model used for data analysis and predictions were done based on three scenarios of SSP1-2.6, SSP3-7.0, and SSP5-8.5 during the period of 2021-2100. This indicated 2.6 and 2.9 times higher percentage of workers who were exposed to heat stress and Ultra Violet (UV) radiation, respectively, in the provinces understudy. This study suggests a holistic approach to address potential impacts of climate change on workers' health and safety that would benefit in making decisions on climate-related planning and developing the adaptation strategies at workplaces.

Risky working conditions and chronic kidney disease

BACKGROUND

Individuals in the workplace are exposed to various environments, tasks, and schedules. Previous studies have indicated a link between occupational exposures and an increased risk of chronic kidney disease (CKD). However, the social conditions of the work environment may also be a crucial contributing factor to CKD. Furthermore, individuals may encounter multiple occupational-related risk factors simultaneously, underscoring the importance of investigating the joint risk of different working conditions on CKD.

METHODS

A prospective analysis of 65,069 UK Biobank participants aged 40 to 69 years without CKD at baseline (2006-2010) was performed. A self-administered questionnaire assessed working conditions and a working conditions risk score were developed. Participants who answered "sometimes" or "often" exposure to occupational heat or occupational secondhand cigarette smoke; involved in shift work or heavy workloads ("usually" or "always"), were grouped as high-risk working conditions. Each working condition was scored as 1 if grouped as high-risk, and 0 if not. The working conditions risk score was equal to the sum of these four working conditions. Cox proportional hazard regression models were used to estimate the associations between working conditions and CKD incidence.

RESULTS

The mean follow-up time was 6.7 years. After adjusting for demographic, lifestyle, and working time factors, the hazard ratios for the development of CKD for heavy workloads, shift work, occupational secondhand cigarette smoke exposure, and occupational heat exposure were 1.24 (95%CI = 1.03, 1.51), 1.33 (95%CI = 1.10, 1.62), 1.13 (95%CI = 1.01, 1.26), 1.11 (95%CI = 0.99, 1.24), respectively. The risk of CKD was found to be significantly associated with an increasing working conditions risk score. Individuals with a working conditions risk score of 4 had an 88.0% (95% CI = 1.05, 3.35) higher risk of developing CKD when compared to those with a working conditions risk score of 0.

CONCLUSIONS

Adverse working conditions, particularly when considered in combination, can significantly elevate the risk of chronic kidney disease (CKD). These results provide a reference for implementing measures to prevent CKD.

Clinical findings and kidney morphology in chronic kidney disease of unknown cause in India

BACKGROUND

Chronic kidney disease of unknown cause (CKDu) is an emerging health problem in India and other countries worldwide. However, clinical descriptions, including kidney pathology, are scarce.

METHODS

This is a descriptive case series of patients with CKDu from an endemic region in India, with a focus on clinical and biochemical characteristics, kidney biopsy findings, and environmental exposure. Patients with suspected CKDu, aged 20-65, and eGFR 30-80 mL/min/1.73 m2 from rural areas with endemic prevalence of CKDu were included. The exclusion criteria were diabetes mellitus, uncontrolled hypertension, proteinuria >1 g/24 h, or other known kidney diseases. The participants underwent kidney biopsies, and blood and urine samples were collected.

RESULTS

Fourteen participants (3 females, 11 males) with a mean eGFR of 53 (range 29-78) mL/min/1.73 m2 were included. Kidney biopsies showed a combination of chronic tubulointerstitial damage, glomerulosclerosis, and glomerular hypertrophy, with varying degrees of interstitial inflammation. Eight participants had polyuria (diuresis ≥ 3 L/day). The urinary sediments were bland, with no haematuria. Serum potassium and sodium levels were, in most cases, normal but within the lower reference interval.

CONCLUSION

The kidney morphology and clinical characteristics in patients with CKDu in India were similar to those described for CKDu in Central America and Sri Lanka.

Sugarcane ash and sugarcane ash-derived silica nanoparticles alter cellular metabolism in human proximal tubular kidney cells

Multiple epidemics of chronic kidney disease of an unknown etiology (CKDu) have emerged in agricultural communities around the world. Many factors have been posited as potential contributors, but a primary cause has yet to be identified and the disease is considered likely multifactorial. Sugarcane workers are largely impacted by disease leading to the hypothesis that exposure to sugarcane ash produced during the burning and harvest of sugarcane could contribute to CKDu. Estimated exposure levels of particles under 10 μm (PM10) have been found to be exceptionally high during this process, exceeding 100 μg/m3 during sugarcane cutting and averaging ∼1800 μg/m3 during pre-harvest burns. Sugarcane stalks consist of ∼80% amorphous silica and generate nano-sized silica particles (∼200 nm) following burning. A human proximal convoluted tubule (PCT) cell line was subjected to treatments ranging in concentration from 0.025 μg/mL to 25 μg/mL of sugarcane ash, desilicated sugarcane ash, sugarcane ash-derived silica nanoparticles (SAD SiNPs) or manufactured pristine 200 nm silica nanoparticles. The combination of heat stress and sugarcane ash exposure on PCT cell responses was also assessed. Following 6-48 h of exposure, mitochondrial activity and viability were found to be significantly reduced when exposed to SAD SiNPs at concentrations 2.5 μg/mL or higher. Oxygen consumption rate (OCR) and pH changes suggested significant alteration to cellular metabolism across treatments as early as 6 h following exposure. SAD SiNPs were found to inhibit mitochondrial function, reduce ATP generation, increase reliance on glycolysis, and reduce glycolytic reserve. Metabolomic analysis revealed several cellular energetics pathways (e.g., fatty acid metabolism, glycolysis, and TCA cycle) are significantly altered across ash-based treatments. Heat stress did not influence these responses. Such changes indicate that exposure to sugarcane ash and its derivatives can promote mitochondrial dysfunction and disrupt metabolic activity of human PCT cells.

Occupational Heat Stress and Kidney Health in Salt Pan Workers

Introduction

Work in heat affects millions of workers. Although kidney function in agricultural workers is increasingly researched, nonagricultural studies are scarce. In coastal salt pans, the absence of occupational exposures to pesticides and other toxicants allows assessment of heat stress alone.

Methods

Seven Indian salt pans were surveyed from 2017 to 2020. Job-specific workload was assessed. Heat stress was characterized as exceeding the wet bulb globe temperature (WBGT)-threshold limit value (TLV) for high and moderate workloads. Preshift and postshift heart rates (HRs), tympanic temperatures, and urine specific gravity (USG) were measured for 352 workers, as were sweat rates (SwR), serum creatinine (SCr), serum uric acid, and urine dipstick. Estimated glomerular filtration rate (eGFR; ml/min per 1.73 m²) was computed. Heat-strain symptoms were assessed using questionnaires.

Results

The mean WBGT was 30.5 ± 1.3 °C (summer) and 27.8 ± 1.9 °C (winter). Water intake during the workday was low, median was one Litre, and most workers (87%) exceeded the TLV for heat stress. Dehydration-related symptoms were frequent in those with high-heat stress, as were cross-shift increases in temperature (≥1°C; 15%), a high USG (≥1.020; 28%), and a high SwR (≥1 l/h; 53%). An eGFR of 60 to 89 ml/min per 1.73 m² was observed in 41% of all workers examined, and 7% had eGFR below 60 ml/min per 1.73 m². The odds ratio for eGFR <90 ml/min per 1.73 m² in workers exceeding the TLV, compared to workers below this limit, adjusted for age and gender was 2.9 (95% CI: 1.3-6.4).

Conclusion

Workplace interventions to prevent heat stress and dehydration in the salt pans and other at-risk industries are urgently required. The findings strengthen the notion that high-heat stress and limited hydration is a risk factor for kidney dysfunction.

Heat stress and heat strain among outdoor workers in El Salvador and Nicaragua

BACKGROUND

There is growing attention on occupational heat stress in Central America, as workers in this region are affected by a unique form of chronic kidney disease. Previous studies have examined wet bulb globe temperatures and estimated metabolic rates to assess heat stress, but there are limited data characterizing heat strain among these workers.

OBJECTIVE

The aims were to characterize heat stress and heat strain and examine whether job task, break duration, hydration practices, and kidney function were associated with heat strain.

METHODS

We used data from the MesoAmerican Nephropathy Occupational Study, a cohort of 569 outdoor workers in El Salvador and Nicaragua who underwent workplace exposure monitoring, including continuous measurement of core body temperature (Tc), heart rate (HR), physical activity, and wet bulb globe temperature (WBGT), over the course of three days in January 2018 - May 2018. Participants represented five industries: sugarcane, corn, plantain, brickmaking, and construction.

RESULTS

Median WBGTs were relatively high (>27 °C) at most sites, particularly when work shifts spanned the afternoon hours (e.g., 29.2 °C among plantain workers). Sugarcane workers, especially cane cutters in both countries and Nicaraguan agrichemical applicators, had the highest estimated metabolic rates (medians: 299-318 kcal/hr). Most workers spent little time on break (<10% of the shift), as determined by physical activity data. Overall, sugarcane workers-particularly those in Nicaragua-experienced the highest Tc and HR values. However, a few workers in other industries reached high Tc (>39 °C) as well. Impaired kidney function (estimated glomerular filtration rate <90 mL/min/1.73 m2) was associated with higher Tc and HR values, even after adjustment.

SIGNIFICANCE

This is the largest study to-date examining heat stress and strain among outdoor workers in Central America. Workers at sugar companies regularly experienced Tc > 38°C (76.9% of monitored person-days at Nicaraguan companies; 46.5% at Salvadoran companies). Workers with impaired kidney function had higher measures of Tc and HR.

IMPACT STATEMENT

This study examined levels of occupational heat stress and heat strain experienced among outdoor workers in five industries in El Salvador and Nicaragua. We characterized heat stress using wet bulb globe temperatures and estimated metabolic rate and heat strain using core body temperature and heart rate. Sugarcane workers, particularly cane cutters and Nicaraguan agrichemical applicators, performed more strenuous work and experienced greater levels of heat strain. Impaired kidney function was associated with higher heart rates and core body temperatures.

Anthropological perspectives on CKDnt in Mexico: time for a paradigm shift on the social determinants of health

In Mexico, the kidneys of individuals in poor and marginalized communities are failing with little warning and no explanation. Commonly referred to as chronic kidney disease of non-traditional origin (CKDnt), this new variant of kidney disease cannot be accounted for by conventional or discrete etiological explanations, but is instead understood to be a consequence of economic development, environmental degradation and precarious working and living conditions. Drawing on two interconnected ethnographic studies, and the intertwining problems of causation and care, this paper will (1) document the social conditions of disease emergence around Lake Chapala, Central Mexico, and (2) follow the haphazard routes kidney patients take to access resource-intensive biotechnical treatments. Its aim is to both challenge and reconceptualize social determinants as social relations in order to fully account for the profoundly contextual, temporal, and dynamic character of this condition, and to rethink opportunities for care and intervention.

Prevalence and predictors of chronic kidney disease of undetermined causes (CKDu) in Western Kenya's "sugar belt": a cross-sectional study

BACKGROUND

Epidemics of chronic kidney disease of undetermined causes (CKDu) among young male agricultural workers have been observed in many tropical regions. Western Kenya has similar climatic and occupational characteristics as many of those areas. The study objectives were to characterize prevalence and predictors of CKDu, such as, HIV, a known cause of CKD, in a sugarcane growing region of Kenya; and to estimate prevalence of CKDu across occupational categories and evaluate if physically demanding work or sugarcane work are associated with reduced eGFR.

METHODS

The Disadvantaged Populations eGFR Epidemiology Study (DEGREE) protocol was followed in a cross-sectional study conducted in Kisumu County, Western Kenya. Multivariate logistic regression was performed to identify predictors of reduced eGFR.

RESULTS

Among 782 adults the prevalence of eGFR < 90 was 9.85%. Among the 612 participants without diabetes, hypertension, and heavy proteinuria the prevalence of eGFR < 90 was 8.99% (95%CI 6.8%, 11.5%) and 0.33% (95%CI 0.04%, 1.2%) had eGFR < 60. Among the 508 participants without known risk factors for reduced eGFR (including HIV), the prevalence of eGFR < 90 was 5.12% (95%CI 3.4%, 7.4%); none had eGFR < 60. Significant risk factors for reduced eGFR were sublocation, age, body mass index, and HIV. No association was found between reduced eGFR and work in the sugarcane industry, as a cane cutter, or in physically demanding occupations.

CONCLUSION

CKDu is not a common public health problem in this population, and possibly this region. We recommend that future studies should consider HIV to be a known cause of reduced eGFR. Factors other than equatorial climate and work in agriculture may be important determinants of CKDu epidemics.

Prevalence of kidney disease of unknown etiology in agricultural workers, Guatemala

Objectives

To determine the prevalence of kidney disease of unknown etiology in banana, melon, and tomato workers in north-eastern Guatemala, and to evaluate the usefulness of a cystatin C blood test for early detection of renal disease.

Methods

This was a cross-sectional, farm-based study of 462 agricultural workers conducted from June to September 2021. Epidemiological and demographic characteristics of the workers were collected through a self-administered questionnaire. Blood samples were obtained to determine glucose, creatinine and cystatin C levels. Anthropometric and clinical data were also recorded.

Results

The prevalence of kidney disease of unknown etiology was 3.03% (95% confidence interval (CI): 1.36-4.70%) based on glomerular filtration rate (GFR-EPI) < 60 mL/min/1.73 m², with a significantly higher prevalence in banana workers (5.67%; 95% CI: 2.16-9.18%) than melon workers (p = 0.009) and tomato workers (p = 0.044). Ten workers (2.16%) had reduced kidney function (GFR-EPI 60-90 mL/min/1.73 m²). The levels of cystatin C showed less variability (coefficient of variation 46.4%) than those of creatinine (coefficient of variation 67.0%), and cystatin C levels in cases with abnormal and reduced kidney function were significantly different from cases with normal kidney function (p < 0.001).

Conclusions

Surveillance of the health of active farm workers and improvement of working conditions, such as sun protection, adequate hydration, and sufficient breaks, are recommended. The significant differences in cystatin C levels between cases with abnormal and reduced kidney function and those with normal kidney function suggest that cystatin C could be a useful measure for early detection of renal disease.

Rising of a global silent killer: critical analysis of chronic kidney disease of uncertain aetiology (CKDu) worldwide and mitigation steps

Chronic kidney disease of uncertain aetiology (CKDu) is an advanced version of chronic kidney disease (CKD) which bears a high burden on the world health economy. More than 200 articles were analysed to understand the disease responsible for more than 30,000 deaths per year. CKDu is a non-communicable occupational disease that has a progressive deterioration of the kidney in the absence of CKD risk factors such as hypertension, diabetes and glomerulonephritis, while the diagnosis is only possible at the later stages when kidney function is no longer effective. Published evidence for the existence of CKDu was found for around 35 countries. This is a growing health issue in Asia, Central America, Africa and Middle East with identified hot spots. Despite many research studies over decades, the exact root causes are still uncertain. Six main suspected causative factors are identified. Those are heat stress, strenuous labour, dehydration, use of agrochemicals, exposure to heavy metals and the use of polluted water and agricultural lands. This review summarizes four key areas which are CKDu and its general medical background, worldwide prevalence, suspected causative factors and potential circumventing steps to mitigate against CKDu. The importance of further studies addressing early detection and surveillance methods, contribution of nephrotoxins in environmental health, soil chemistry on transporting nephrotoxins, geological parameters which influence the prevalence of the disease and other related sectors to overcome the mysterious nature is highlighted. Mitigation steps to lessen the burden of CKDu are also identified.

Environmental and Social Factors Associated with High Chronic Kidney Disease Mortality Rates in Municipalities of Guatemala: An Ecological Study of Municipal-Level Mortality Data

The purpose of this study was to determine the association between social and environmental indicators and high mortality rates from chronic kidney disease (CKD) in municipalities of Guatemala. An ecological study of municipal-level factors associated with CKD mortality in Guatemala was conducted. Crude mortality rates were calculated for the 2009-2019 period for each of the country's 340 municipalities, by gender and age groups. Municipal-level social and environmental indicators were used as independent variables. Linear regression was used for bivariate and multivariate analysis. A total of 28,723 deaths from CKD were documented for the 2009-2019 period. Average crude mortality rate for all ages for the country's 340 municipalities was 70.66 per 100,000 [0-502.99]. Very highly positive associations with high mortality rates were found in two agrarian territories where land use is mainly for permanent crops (e.g., sugar cane, coffee, rubber, banana, plantain, African palm) and pastures for cattle, with very low percentages of land covered by forests or protected areas. Social factors related to poverty and environmental factors related to agricultural use of land may play a role in the high CKD mortality rates documented in a cluster of municipalities of Guatemala.

Exposure of patients with chronic kidney disease on dialysis to pesticides

INTRODUCTION

Pesticides can trigger kidney disease.

OBJECTIVE

To describe the exposure to pesticides of patients with chronic kidney disease on dialysis.

METHODS

Quantitative and descriptive field research, with 90 patients with chronic kidney disease on dialysis in two hemodialysis units in the state of Santa Catarina, through the application of a structured questionnaire. Participants were divided into two groups: with and without exposure to pesticides. The questionnaire was applied in hemodialysis clinics during treatment. Laboratory test values were collected from clinical records. Data were analyzed using descriptive statistics and association using the chi-square test. For laboratory test data, a comparison of means was performed using the unpaired Student's t-test between the groups.

RESULTS

The mean age of exposed participants was 58 years (±13.7; minimum = 23; maximum = 75) and that of non-exposed participants was 64 years old (±13.9; minimum = 35; maximum = 96). Of the 90 patients, 30% were exposed to pesticides. The mean exposure time was 6.7 ± 3.8 hours/day. There was a statistically significant association between the preparation of the mixture with pesticides and diabetes (p ≤ 0.048). There was no statistically significant difference between the results of laboratory tests in the exposed and non-exposed groups.

CONCLUSION

This study shows that pesticides can be triggering factors for chronic kidney disease (CKD); however, we must expand research in this field to prove the relationship between exposure to pesticides and CKD.

Prevalence and Geographic Distribution of Self-Reported Chronic Kidney Disease and Potential Risk Factors in Central America

BACKGROUND

Cases for chronic kidney disease of unknown etiology (CKDu) are increasing in specific disease hotspots located in rural agricultural communities over Central America. The goal of the study was to estimate the prevalence and geographic distribution of self-reported work-related CKD and associated risk factors for CKDu by industry sector in Central America.

METHODS

We calculated the prevalence and distribution of self-reported CKD, work-related CKD, and suspected CKDu risk factors among the 9032 workers in the Second Central American Survey of Working Conditions and Health (II ECCTS, 2018). We mapped the distribution of suspected CKDu risk factors to work-related CKDu and weather conditions using average annual temperatures.

RESULTS

The primary and secondary industry sectors showed the highest proportion of males, suspected CKDu risk factors, and work-related CKD. Age (30-49 years: OR = 2.38, 95% CI 1.03-5.51), ethnicity (mestizo: OR, 7.44, 95% CI: 2.14-25.82), and exposure to high physical work demands (OR = 2.45, 95% CI: 1.18-5.09) were associated with work-related CKD. The majority of work-related CKD were reported in the western parts of Honduras and Nicaragua, in hot temperature regions, and overlapped with those areas with a high density of CKDu risk factors. Finally, some areas clustered CKDu risk factors without any work-related CKD points, mainly in the western part of Guatemala.

CONCLUSION

Our findings supplement prior CKDu findings regarding a high prevalence of work-related CKD among 30- to 49-year-old mestizo males in the primary and secondary sectors, in hot temperature areas, in the central and western region, and overlapping with persons reporting two or more CKDu risk factors. Moreover, several geographic areas with CKDu risk factor clusters had no reported work-related CKD. These areas represent new industries and sectors to be monitored for possible future increases of CKDu cases.

Targeting workload to ameliorate risk of heat stress in industrial sugarcane workers

OBJECTIVE

The aim of this study was to quantify the physiological workload of manual laborers in industrial sugarcane and assess the effect of receiving a rest, shade, and hydration intervention to reduce heat stress exposure risk.

METHODS

In an observational study, physiological workload was evaluated for burned cane cutters (BCC), seed cutters (SC) and drip irrigation repair workers (DIRW) using heart rate (HR) recorded continuously (Polar®) across a work shift. Workers' percentage of maximal HR (%HRmax), time spent in different HR zones, and estimated core temperature (ECTemp) were calculated. The effect of increasing rest across two harvests was evaluated for BCC and SC.

RESULTS

A total of 162 workers participated in this study [52 BCC (all male), 71 SC (13 female) and 39 DIRW (16 female)]. Average %HRmax across a work shift was similar between BCC and SC (BCC: 58%, SC: 59%), but lower in DIRW (51%). BCC and SC spent similar proportions of work shifts at hard/very hard intensities (BCC: 13%, SC: 15%), versus DIRW who worked mostly at light (46%) or light-moderate (39%) intensities. SC maximum ECTemp reached 38.2°C, BCC 38.1°C; while DIRW only reached 37.7°C. Females performed at a higher %HRmax than males across work shifts (SC 64% versus 58%; DIRW 55% versus 49%). An additional rest period was associated with a lower average %HRmax across a work shift in BCC.

CONCLUSION

In this setting, BCC and SC both undertake very physiologically demanding work. Females maintained a higher workload than male co-workers. Regulated rest periods each hour, with water and shade access, appears to reduce physiological workload/strain.

End-stage renal disease incidence in a cohort of US firefighters from San Francisco, Chicago, and Philadelphia

BACKGROUND

Firefighters perform strenuous work in hot environments, which may increase their risk of chronic kidney disease. The purpose of this study was to evaluate the risk of end-stage renal disease (ESRD) and types of ESRD among a cohort of US firefighters compared to the US general population, and to examine exposure-response relationships.

METHODS

ESRD from 1977 through 2014 was identified through linkage with Medicare data. ESRD incidence in the cohort compared to the US population was evaluated using life table analyses. Associations of all ESRD, systemic ESRD, hypertensive ESRD, and diabetic ESRD with exposure surrogates (exposed days, fire runs, and fire hours) were examined in Cox proportional hazards models adjusted for attained age (the time scale), race, birth date, fire department, and employment duration.

RESULTS

The incidence of all ESRD was less than expected (standardized incidence ratio (SIR) = 0.79; 95% confidence interval = 0.69-0.89, observed = 247). SIRs for ESRD types were not significantly increased. Positive associations of all ESRD, systemic ESRD, and hypertensive ESRD with exposed days were observed: however, 95% confidence intervals included one.

CONCLUSIONS

We found little evidence of increased risk of ESRD among this cohort of firefighters. Limitations included the inability to evaluate exposure-response relationships for some ESRD types due to small observed numbers, the limitations of the surrogates of exposure, and the lack of information on more sensitive outcome measures for potential kidney effects.

Social determinants and chronic kidney disease of undetermined origin in childhood: Its communication and understanding described by families in Lake Chapala, Mexico

This work is based on the recognition of the existence of a complex relationship between social and environmental determinants and infants with chronic kidney disease of non-traditional etiology (CKDnT). The aim is to understand how the Social and Environmental Determinants are settled and its influence to the CKDnT in childhood, through knowledge built from the population that has lived the experience of this disease. This research was carried out with a narrative-conversational design. The experience of CKDnT was organized in stories focused on the experience of families in the social and environmental context where they live, get sick, suffer, and die from the disease. In the dialogue emerges the intersection of the social determinants of the disease, the different ways of life, and the relationship with the health services that attend them.

Where do you live and what do you do? Two questions that might impact your kidney health

In many cases the social determinants of health need to be assessed through their interaction with environmental factors. This review looks at the impact of physical location and occupation of individuals on their kidney health. It examines the effect of living at high altitude on kidney function and the relationship between extreme cold or hot temperatures and the incidence of kidney injury. It reviews as well the many occupations that have been linked to kidney disease in high-income and low-and-middle-income countries. As a conclusion, this overview proposes preventive recommendations that could be individualized based on weather, altitude, socio-economic level of the country and occupation of the individual.

Exposição de pacientes com doença renal crônica em tratamento dialítico aos agrotóxicos

Resumo Introdução: O uso de agrotóxicos pode desencadear doença renal. Objetivo: Descrever a exposição a agrotóxicos de pacientes com doença renal crônica em tratamento dialítico. Métodos: Pesquisa de campo, quantitativa e descritiva, com 90 portadores de doença renal crônica em tratamento dialítico em duas unidades de hemodiálise no estado de Santa Catarina, por meio da aplicação de um questionário estruturado. Os participantes foram divididos em dois grupos: sem e com exposição a agrotóxicos. O questionário foi aplicado nas clínicas de hemodiálise durante o tratamento. Foram coletados valores de exames laboratoriais dos prontuários clínicos. Os dados foram analisados pela estatística descritiva e associação pelo teste qui-quadrado. Para os dados dos exames laboratoriais, foi realizada comparação de médias pelo teste t de Student não pareado entre os grupos. Resultados: A idade média dos participantes expostos foi de 58 anos (±13,7; mínimo = 23; máximo = 75) e a dos não expostos, de 64 anos (±13,9; mínimo = 35; máximo = 96). Dos 90 pacientes, 30% foram expostos a agrotóxicos. O tempo médio de exposição foi de 6,7 ± 3,8 horas/dia. Houve associação estatística significativa entre o preparo da calda com agrotóxicos e a presença de diabetes (p ≤ 0,048). Não houve diferença estatística significativa entre os resultados dos exames laboratoriais do grupo exposto e do não exposto. Conclusão Esta pesquisa evidencia que os agrotóxicos podem ser fatores desencadeadores da doença renal crônica (DRC), entretanto sugere-se ampliar pesquisas na área que possam comprovar a relação entre exposição a agrotóxicos e DRC.

Mesoamerican Endemic Nephropathy (MeN): A Disease Reported in Adults That May Start Since Childhood?

Mesoamerican endemic nephropathy (MeN) is a type of chronic kidney disease (CKD) of uncertain etiology that occurs along the Pacific coast of the southern part of Mexico and Central America. During the past 20 years MeN has become a leading cause of death in the region, clamming close to 50,000 lives, with 40% of these deaths occurring in young people. The cause remains unknown, but most researchers believe in a multifactorial etiology that includes social determinants of poverty. Existing evidence suggests that subclinical kidney injury begins early in life and leads to a higher than expected prevalence of CKD among children in Central America. Access to health services in the region, specifically kidney replacement therapy, remains limited. We proposed a strategy to address the perceived needs and urge coordinated efforts of governments, academic organizations, and international bodies to develop a comprehensive plan of action to mitigate this situation among the vulnerable and economically disadvantaged population.

High prevalence of chronic kidney disease of unknown etiology among workers in the Mesoamerican Nephropathy Occupational Study

BACKGROUND

Mortality from chronic kidney disease of unknown etiology (CKDu) is extremely high along the Pacific coast of Central America, particularly among sugarcane workers. The Mesoamerican Nephropathy Occupational Study (MANOS) is a prospective cohort study of CKDu among agricultural and non-agricultural workers in El Salvador and Nicaragua. The objective of this manuscript is to describe the MANOS cohort recruitment, baseline data collection, and CKDu prevalence after two rounds.

METHODS

Workers with no known diabetes, hypertension, or CKD were recruited from sugarcane, corn, plantain, brickmaking, and road construction industries (n = 569). Investigators administered questionnaires, collected biological samples, and observed workers for three consecutive workdays at the worksite. Serum specimens were analyzed for kidney function parameters, and used to calculate estimated glomerular filtration rate (eGFR). At six months, serum was collected again prior to the work shift. CKD at baseline is defined as eGFR ≤ 60 ml/min/1.73m2 at both timepoints. Age-standardized prevalence was calculated by industry, country, and demographic measures. Kidney function parameters were compared by CKD status.

RESULTS

Prevalence of CKD at baseline was 7.4% (n = 42). Age-standardized prevalence was highest in Salvadoran sugarcane (14.1%), followed by Salvadoran corn (11.6%), and Nicaraguan brickmaking (8.1%). Nicaraguan sugarcane had the lowest prevalence, likely due to kidney function screenings prior to employment.

CONCLUSION

Despite efforts to enroll participants without CKD, our identification of prevalent CKD among agricultural and non-agricultural workers in the MANOS cohort indicates notable kidney disease in the region, particularly among sugarcane workers.

Markers of kidney tubular and interstitial injury and function among sugarcane workers with cross-harvest serum creatinine elevation

OBJECTIVES

Serum creatinine (SCr) is a routine marker of kidney injury but also increases with dehydration and muscular work. This study was to elucidate whether increase in SCr is associated with more specific markers of kidney tubular and interstitial injury and function, during prolonged heat stress among workers at high risk of chronic kidney disease of non-traditional origin (CKDnt).

METHODS

Urine monocyte chemoattractant protein-1 (MCP-1), kidney injury molecule-1 (KIM-1), calbindin, glutathione S-transferase-π (GST-π), clusterin, interleukin 18 and albumin, fractional excretion of potassium (FEK), blood haemoglobin, serum potassium, ferritin and erythropoietin were measured before and after harvest in a sample of 30 workers with a ≥0.3 mg/dL SCr increase across harvest (cases), and 53 workers with stable SCr (controls).

RESULTS

Urine MCP-1 (p for differential cross-harvest trend <0.001), KIM-1 (p=0.002), calbindin (p=0.02), GST-π (p=0.04), albumin (p=0.001) and FEK (p<0.001) increased in cases, whereas blood haemoglobin (p<0.001) and serum erythropoietin (p<0.001) decreased.

CONCLUSION

Several markers of tubular and interstitial injury and function changed as SCr increased across a harvest season, supporting the use of SCr as an indicator of kidney injury in physically active workers regularly exposed to heat stress. Repeated injury similar to that described here, and continued work under strenuous and hot conditions with similarly elevated injury markers is likely to worsen and possibly initiate CKDnt.

THIRSTY FOR FRUCTOSE: Arginine Vasopressin, Fructose, and the Pathogenesis of Metabolic and Renal Disease

We review the pathways by which arginine vasopressin (AVP) and hydration influence the sequelae of the metabolic syndrome induced by high fructose consumption. AVP and inadequate hydration have been shown to worsen the severity of two phenotypes associated with metabolic syndrome induced by high fructose intake-enhanced lipogenesis and insulin resistance. These findings have implications for those who frequently consume sweeteners such as high fructose corn syrup (HFCS). Patients with metabolic syndrome are at higher risk for microalbuminuria and/or chronic kidney disease; however, it is difficult to discriminate the detrimental renal effects of the metabolic syndrome from those of hypertension, impaired glucose metabolism, and obesity. It is not surprising the prevalence of chronic renal insufficiency is growing hand in hand with obesity, insulin resistance, and metabolic syndrome in those who consume large amounts of fructose. Higher AVP levels and low hydration status worsen the renal insufficiency found in patients with metabolic syndrome. This inter-relationship has public health consequences, especially among underserved populations who perform physical labor in environments that place them at risk for dehydration. MesoAmerican endemic nephropathy is a type of chronic kidney disease highly prevalent in hot ambient climates from southwest Mexico through Latin America. There is growing evidence that this public health crisis is being spurred by greater fructose consumption in the face of dehydration and increased dehydration-dependent vasopressin secretion. Work is needed at unraveling the mechanism(s) by which fructose consumption and increased AVP levels can worsen the renal disease associated with components of the metabolic syndrome.

Kidney Function in Rice Workers Exposed to Heat and Dehydration in Costa Rica

The aim of this study was to evaluate heat exposure, dehydration, and kidney function in rice workers over the course of three months, in Guanacaste, Costa Rica. We collected biological and questionnaire data across a three-month-period in male field (n = 27) and other (n = 45) workers from a rice company where chronic kidney disease of unknown origin (CKDu) is endemic. We used stepwise forward regression to determine variables associated with estimated glomerular filtration rate eGFR at enrollment and/or change in eGFR, and Poisson regression to assess associations with incident kidney injury (IKI) over the course of three months. Participants were 20−62 years old (median = 40 in both groups). Dehydration was common (≥37%) in both groups, particularly among other workers at enrollment, but field workers were more exposed to heat and had higher workloads. Low eGFR (<60 mL/min/1.73 m2) was more prevalent in field workers at enrollment (19% vs. 4%) and follow-up (26% vs. 7%). Field workers experienced incident kidney injury (IKI) more frequently than other workers: 26% versus 2%, respectively. Age (β = −0.71, 95%CI: −1.1, −0.4), current position as a field worker (β = −2.75, 95%CI: −6.49, 0.99) and past work in construction (β = 3.8, 95%CI: −0.1, 7.6) were included in the multivariate regression model to explain eGFR at enrollment. The multivariate regression model for decreased in eGFR over three month included current field worker (β = −3.9, 95%CI: −8.2, 0.4), current smoking (β= −6.2, 95%CI: −13.7−1.3), dehydration (USG ≥ 1.025) at both visits (β= −3.19, 95%CI: −7.6, 1.2) and pain medication at follow-up (β= −3.2, 95%CI: −8.2, 1.95). Current fieldwork [IR (incidence rate) = 2.2, 95%CI 1.1, 5.8) and being diabetic (IR = 1.8, 95%CI 0.9, 3.6) were associated with IKI. Low eGFR was common in field workers from a rice company in Guanacaste, and being a field worker was a risk factor for IKI, consistent with the hypothesis that occupational heat exposure is a critical risk factor for CKDu in Mesoamerica.

Large difference but high correlation between creatinine and cystatin C estimated glomerular filtration rate in Mesoamerican sugarcane cutters

OBJECTIVES

To explore the relationship between creatinine and cystatin C based estimated glomerular filtration rate (eGFR) in actively working sugarcane cutters.

METHODS

This cohort study included 458 sugarcane cutters from Nicaragua and El Salvador. Serum samples were taken before and at end of harvest seasons and analysed for creatinine and cystatin C. Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas were used to calculate eGFRs based on creatinine (eGFR_cr), cystatin C (eGFR_cys) and both creatinine and cystatin C (eGFR_crcys) at each time point. Bland-Altman plots and paired t-tests were used to compare the difference between eGFR_cr and eGFR_cys, and the difference in eGFRs between before and at end of the harvest seasons.

RESULTS

The mean eGFR_cr was higher than eGFR_cys in both cohorts; absolute difference 22 mL/min/1.73 m² (95% CI 21 to 23) in Nicaragua and 13 mL/min/1.73 m² (95% CI 11 to 15) in El Salvador. Correlations between eGFR_cr and eGFR_cys were high, with r=0.69, 0.77 and 0.67 in Nicaragua at pre-harvest, end-harvest and cross-harvest, and r=0.89, 0.89 and 0.49 in El Salvador.

CONCLUSIONS

Creatinine increases among heat-stressed workers reflect reduced glomerular filtration as estimated using eGFR_cys, a marker independent of muscle mass and metabolism. The discrepancy between eGFR_cr and eGFR_cys may indicate reduced glomerular filtration of larger molecules and/or systemic bias in CKD-EPI performance in this population.

Workplace Intervention for Heat Stress: Essential Elements of Design, Implementation, and Assessment

Heat stress is associated with numerous health effects that potentially harm workers, especially in a warming world. This investigation occurred in a setting where laborers are confronted with occupational heat stress from physically demanding work in high environmental temperatures. Collaboration with a major Nicaraguan sugarcane producer offered the opportunity to study interventions to prevent occupational heat-stress-related kidney disease. Two aims for this study of a rest-shade-water intervention program were: (1) describe the evolving intervention, summarize findings that motivated proposed improvements, assess impact of those improvements, and identify challenges to successful implementation and (2) extract primary lessons learned about intervention research that have both general relevance to investigations of work-related disease prevention and specific relevance to this setting. The learning curve for the various stakeholders as well as the barriers to success demonstrate that effectiveness of an intervention cannot be adequately assessed without considerations of implementation. Designing, effectively implementing, and assessing both health impacts and implementation quality is a resource-intensive endeavor requiring a transdisciplinary approach. Both general and specific lessons learned are presented for decisions on study design and study elements, implementation assessment, and management engagement in understanding how productivity and health can be successfully balanced and for building effective communication between investigators and all levels of management.

Sex and gender differences in chronic kidney disease and access to care around the globe

The difference between sex, the biological construct, and gender, the social construct, may be most evident in settings of vulnerability. Globally, chronic kidney disease is more prevalent among women, but the prevalence of end-stage kidney failure, and especially receipt of kidney replacement therapy, is higher in men. These differences likely reflect a combination of physiological and social/structural risk factors that independently modulate kidney disease and/or its progression. The distribution of the most common risk factors such as hypertension and obesity differ between men and women and may impact disease risk differentially. Social and structural gender-related inequities remain stark across the globe. More women live in poverty, receive less education, and are more dependent on others for health care decision making, but men may have a higher risk of injury, occupational exposures, and less access to screening, prevention, and primary care. In this article, we explore how social determinants of health affect kidney disease risk and access to care differentially across genders, and differently across the globe. We also describe specific challenges experienced by boys and girls with kidney disease, how culture and geography may impact kidney care in places where resources are particularly limited such as sub-Saharan Africa, and give examples of social and structural circumstances that place young men and women at high risk of kidney disease in Mexico and Central America, illustrated by case vignettes. The coronavirus disease-2019 pandemic has raised awareness of pervasive gender-based inequities within all societies. This applies to kidney disease and is not new. The nephrology community must add its voice to the calls for action, for a more just society overall, and for the recognition of the roles of sex and gender as modulators of kidney disease risk and access to care.

The Latin American Dialysis and Renal Transplantation Registry: report 2019

Background

Chronic kidney disease (CKD) in Latin America (LA) continues to represent a challenge due to the burden of disease it causes and the difficulty in accessing treatment. LA has a total population of 652 million people living in 20 countries that occupy an area of 19.2 million km². The Latin American Dialysis and Renal Transplantation Registry (LADRTR), founded in 1991, has collected data and reports on patients receiving kidney replacement therapy (KRT) since 1993. This article summarizes the registry data for 2019.

Methods

Participating countries complete an annual survey collecting aggregated data on incident and prevalent patients on KRT in all modalities. The different treatment modalities considered were hemodialysis (HD), peritoneal dialysis (PD) and living functioning kidney graft (LFG). National gross domestic product per capita (GDP, expressed in US dollars) and life expectancy at birth (LEB) corresponding to the year 2019 were collected from the World Bank Data Bank. Prevalence and incidence were compared with previous years and were also correlated with GDP and LEB.

Results

On 31 December 2019 a total of 432 610 patients were in KRT in LA, corresponding to an overall unadjusted prevalence of 866 per million population (pmp). Regarding treatment modality, 66.7% of the prevalent patients were treated with HD and 9.3% with PD while 24% of the patients had an LFG. A total of 85 224 patients started KRT in LA, representing a total unadjusted incidence rate of 168 pmp. Diabetic nephropathy as a cause of CKD continues to be a relevant percentage (36%) and five countries reported CKD of nontraditional causes. The kidney transplant rate in the region was 22 pmp, varying from 1 to >60 pmp. The total prevalence of KRT correlated positively with GDP per capita (r² = 0.6, P < 0.01) and LEB (r² = 0.23, P < 0.05). The overall incidence rate also significantly correlated with GDP (r² = 0.307, P < 0.05). The overall unadjusted mortality rate was 13%.

Conclusion

Accessibility to KRT is still limited in LA. It is necessary to continue the efforts made by each country and the Latin American Society of Nephrology and Hypertension to guarantee equal access to treatment.

Impacts of Climate Change and Heat Stress on Farmworkers' Health: A Scoping Review

Due to the continuous rise of global temperatures and heatwaves worldwide as a result of climate change, concerns for the health and safety of working populations have increased. Workers in the food production chain, particularly farmworkers, are especially vulnerable to heat stress due to the strenuous nature of their work, which is performed primarily outdoors under poor working conditions. At the cross-section of climate change and farmworkers' health, a scoping review was undertaken to summarize the existing knowledge regarding the health impacts associated with climate change and heat stress, guide future research toward better understanding current and future climate change risks, and inform policies to protect the health and safety of agricultural workers. A systematic search of 5 electronic databases and gray literature websites was conducted to identify relevant literature published up until December 2021. A total of 9045 records were retrieved from the searches, of which 92 articles were included in the final review. The majority of the reviewed articles focused on heat-related illnesses (n = 57) and kidney diseases (n = 28). The risk factors identified in the reviewed studies included gender, dehydration, heat strain, wearing inappropriate clothing, workload, piece-rate payment, job decision latitude, and hot environmental conditions. On the other hand, various protective and preventive factors were identified including drinking water, changing work hours and schedule of activities, wearing appropriate clothing, reducing soda consumption, taking breaks in shaded or air-conditioned areas, and increasing electrolyte consumption in addition to improving access to medical care. This review also identified various factors that are unique to vulnerable agricultural populations, including migrant and child farmworkers. Our findings call for an urgent need to expand future research on vulnerable agricultural communities including migrant workers so as to develop effective policies and interventions that can protect these communities from the effects of heat stress.

Hospitalised heat-related acute kidney injury in indoor and outdoor workers in the USA

OBJECTIVES

To characterise heat-related acute kidney injury (HR-AKI) among US workers in a range of industries.

METHODS

Two data sources were analysed: archived case files of the Occupational Safety and Health Administration's (OSHA) Office of Occupational Medicine and Nursing from 2010 through 2020; and a Severe Injury Reports (SIR) database of work-related hospitalisations that employers reported to federal OSHA from 2015 to 2020. Confirmed, probable and possible cases of HR-AKI were ascertained by serum creatinine measurements and narrative incident descriptions. Industry-specific incidence rates of HR-AKI were computed. A capture-recapture analysis assessed under-reporting in SIR.

RESULTS

There were 608 HR-AKI cases, including 22 confirmed cases and 586 probable or possible cases. HR-AKI occurred in indoor and outdoor industries including manufacturing, construction, mail and package delivery, and solid waste collection. Among confirmed cases, 95.2% were male, 50.0% had hypertension and 40.9% were newly hired workers. Incidence rates of AKI hospitalisations from 1.0 to 2.5 hours per 100 000 workers per year were observed in high-risk industries. Analysis of overlap between the data sources found that employers reported only 70.6% of eligible HR-AKI hospitalisations to OSHA, and only 41.2% of reports contained a consistent diagnosis.

CONCLUSIONS

Workers were hospitalised with HR-AKI in diverse industries, including indoor facilities. Because of under-reporting and underascertainment, national surveillance databases underestimate the true burden of occupational HR-AKI. Clinicians should consider kidney risk from recurrent heat stress. Employers should provide interventions, such as comprehensive heat stress prevention programmes, that include acclimatisation protocols for new workers, to prevent HR-AKI.

Longitudinal assessment of kidney function in migrant farm workers

Chronic kidney disease of unknown etiology (CKDu) is an epidemic that affects young agricultural workers in several warm regions of the world. However, there is a lack of monitoring of kidney issues in regions with extremely warm environments such as the Northwest of Mexico, a semi-arid region with a growing agricultural industry, where migrant and seasonal farm workers (MSFWs) travel to work in the fields. The objective of this study was to longitudinally assess kidney functioning of MSFWs in relation to pesticide exposure, heat stress and dehydration in a large-scale farm in Mexico. We enrolled 101 MSFWs, of whom 50 were randomly selected to work in an organic certified area and 51 were randomly selected to work in a conventional area. We also enrolled 50 office workers within the same region as a reference group. We collected urine and blood samples from all workers in addition to demographic, behavioral, and occupational characteristics. The physiological strain index (PSI) was used to estimate workers' heat strain. Sampling was conducted at pre-harvest (March) and late in the harvest (July). Linear mixed models were built with the estimated glomerular filtration rate (eGFR) as the dependent variable. We found a significant decrease in kidney function in MSFWs compared to office workers. By the late harvest, one MSFW developed kidney disease, two MSFWs suffered a kidney injury, and 14 MSFWs were at risk of a kidney injury. We found that the eGFR in MSFWs decreased significantly from pre-harvest (125 ± 13.0 mL/min/1.73 m2) to late harvest (109 ± 13.6 mL/min/1.73 m2) (p < 0.001), while no significant change was observed in office workers. The eGFR was significantly lower in MSFWs who worked in the conventional field (101.2 ± 19.4 mL/min/1.73 m2) vs the organic field (110.9 ± 13.6 mL/min/1.73 m2) (p = 0.002). In our final model, we found that dehydration was associated with the decrease of eGFR. We also found an interaction between heat strain and job category, as a significant decline in eGFR by job category (conventional/organic MSFWs and office workers) was related to an increase in heat strain. This suggests that pesticide exposure needs to be considered in combination with heat stress and dehydration. This study provides valuable information on kidney function in MSFWs, and it shows the importance of early long-term monitoring in farm workers in other regions where CKDu has not been evaluated yet.

The Prevention of Occupational Heat Stress in Sugarcane Workers in Nicaragua-An Interpretative Phenomenological Analysis

Background: Chronic kidney disease of non-traditional origin (CKDnt) is an ongoing epidemic that has taken the lives of tens of thousands of people in Mesoamerica, also affecting other tropical geographies. Occupational heat stress, which will increase worldwide as climate change persists, has been identified as a primary trigger of kidney injury and reduced renal function. At Nicaragua's largest sugarcane mill, the water, rest, and shade (WRS) intervention has proven to reduce the risk of heat stress and kidney injury effectively as assessed by the research and policy NGO La Isla Network (LIN) and their academic partners, who have worked with the sugar mill to improve the design of their intervention system. However, discrepancies between intervention design and implementation have been found. This study explores the perceptions of the WRS intervention in the company from the perspective of positions responsible for the workers' environment and heat stress prevention implementation.

Methods: A qualitative design was used in the study. Twenty-one key informants of low and middle management, field assistants, and two members from LIN took part in the study. Semi-structured interviews were used to collect the data. Interviews' transcriptions were analyzed using interpretative phenomenological analysis (IPA).

Results: Four main themes were developed in the analysis of the data: “A worthwhile struggle,” “Culture of care”, “Traditional production culture Vs. Culture of care,” and “The importance of the formalization of care.” Each theme contained sub-themes, all of which were further discussed in the light of organizational psychology.

Conclusion and Implications: Discretionary differences resulting in low and middle management prioritizing production over health protection appeared to relate to a fair part of the implementation challenges and indicate that more efforts are needed to align operations' production and health goals. Education enhancement might be necessary, while further focus on health metrics for performance assessment might offer an opportunity to level perceived incentives and value of health and production.

Organophosphate pesticides and progression of chronic kidney disease among children: A prospective cohort study

BACKGROUND

Growing evidence suggests that exposure to environmental chemicals, such as pesticides, impacts renal function and chronic kidney disease (CKD). However, it is not clear if pesticides may affect CKD progression and no studies exist in children.

OBJECTIVES

The objective of this study was to examine associations between serially measured urinary OP pesticide metabolites and clinical and laboratory measures of kidney function over time among children with CKD.

METHODS

This study used data on 618 participants enrolled in the CKD in Children study (CKiD), a cohort study of pediatric CKD patients from the US and Canada. Children were followed over an average of 3.0 years (standard deviation (SD) = 1.6) between 2005 and 2015. In serially collected urine samples over time, six nonspecific dialkyl phosphate (DAP) metabolites of OP pesticides were measured. Biomarkers of tubular injury (kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)) and oxidant stress (8-hydroxy-2'-deoxyguanosine (8-OHdG) and F2-isoprostane) were determined in the same specimens. Estimated glomerular filtration rate (eGFR), proteinuria, and blood pressure were assessed annually.

RESULTS

DAPs were associated with increased KIM-1 and 8-OHdG throughout follow-up. A standard deviation increase in ∑diethyl metabolites was associated with increases of 11.9% (95% Confidence Interval (CI): 4.8%, 19.4%) and 13.2% (95% CI: 9.3%, 17.2%) in KIM-1 and 8-OHdG over time, respectively. DAPs were associated with lower eGFR at baseline and higher eGFR over subsequent years.

CONCLUSIONS

These findings provide preliminary evidence suggesting that urinary DAP metabolites are associated with subclinical kidney injury among children with CKD, which may signal the potential for clinical events to manifest in the future. The results from this study are significant from both a clinical and public health perspective, given that OP pesticide exposure is a modifiable risk factor.

Catalyzing Knowledge-Driven Discovery in Environmental Health Sciences through a Community-Driven Harmonized Language

Harmonized language is critical for helping researchers to find data, collecting scientific data to facilitate comparison, and performing pooled and meta-analyses. Using standard terms to link data to knowledge systems facilitates knowledge-driven analysis, allows for the use of biomedical knowledge bases for scientific interpretation and hypothesis generation, and increasingly supports artificial intelligence (AI) and machine learning. Due to the breadth of environmental health sciences (EHS) research and the continuous evolution in scientific methods, the gaps in standard terminologies, vocabularies, ontologies, and related tools hamper the capabilities to address large-scale, complex EHS research questions that require the integration of disparate data and knowledge sources. The results of prior workshops to advance a harmonized environmental health language demonstrate that future efforts should be sustained and grounded in scientific need. We describe a community initiative whose mission was to advance integrative environmental health sciences research via the development and adoption of a harmonized language. The products, outcomes, and recommendations developed and endorsed by this community are expected to enhance data collection and management efforts for NIEHS and the EHS community, making data more findable and interoperable. This initiative will provide a community of practice space to exchange information and expertise, be a coordination hub for identifying and prioritizing activities, and a collaboration platform for the development and adoption of semantic solutions. We encourage anyone interested in advancing this mission to engage in this community.