Association between occupational heat stress and DNA damage in lymphocytes of workers exposed to hot working environments in a steel industry in Southern India

Heat and health of occupational workers: a short summary of literature

Globally, occupational workers suffer various health impacts due to extreme heat. In this short review, we examine the literature discussing health impacts of heat on occupational workers, and then discuss certain individual and institutional measures needed to address the problem. Though the available literature in the recent decade discusses health impacts of heat on workers as various heat-related illnesses, we found very few studies examining how occupational workers suffer from issues concerning cardiovascular health, neurological health, respiratory health, and mental health. In this regard, we highlight the need for more studies to examine how occupational workers exposed to extreme heat conditions suffer from fatal health issues like cardiovascular attack, brain stroke, and other ailments impacting vital organs of the body. Occupational workers across the world should be made aware of measures to protect themselves from extreme heat. Further, countries should develop occupational heat safety guidelines with statutory effect.

Study on thermal health and its safety management mode for the working environment

Thermal health concerns have gained significant attention due to the heightened health risks faced by workers who are exposed to extreme thermal environments for prolonged periods. To ensure the occupational health and safety of such workers, and to enhance work efficiency, it is imperative to examine the characteristics of thermal health in the working environment. This study proposes three key elements of thermal health in the working environment, namely thermal health states, absence of heat-related illnesses, and heat adaptability, which can be used to develop a safety management framework for thermal health. By exploring the interconnections between these elements, the study summarizes their features and outlines the necessary precautions to safeguard them. The PDCA (plan/do/check/action) cycle management mode is utilized as a framework, with the three components of thermal health forming the core, to establish a safety management mode for thermal health. To ensure that employees work in a safe, healthy, comfortable, and productive environment, the assessment and control objectives of the thermal environment are regularly revised through the use of labor protection technology and thermal environment control technology. This paper presents a PDCA cycle safety management mode based on the characteristics of thermal health, which offers novel insights and approaches for assessing and managing workers' thermal health.

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.

Effect of heat stress on DNA damage: a systematic literature review

Thermal stress has a direct effect on various types of DNA damage, which depends on the stage of the cell cycle when the cell is exposed to different climate conditions. A literature review was conducted to systematically investigate and assess the overall effect of heat stress and DNA damage following heat exposure. In this study, electronic databases including PubMed, Scopus, and Web of Science were searched to find relevant literature on DNA damage in different ambient temperatures. Outcomes included (1) measurement of DNA damage in heat exposure, (2) three different quantification methods (comet assay, 8-hydroxy-2-deoxyguanosine (8-OHdG), and γ-H2AX), and (3) protocols used for moderate (31) and high temperatures (42). The evidence shows that long exposure and very high temperature can induce an increase in DNA damage through aggregate in natural proteins, ROS generation, cell death, and reproductive damage in hot-humid and hot-dry climate conditions. A substantial increase in DNA damage occurs following acute heat stress exposure, especially in tropical and subtropical climate conditions. The results of this systematic literature review showed a positive association between thermal stress exposure and inhibition of repair of DNA damage.

Analyzing occupational heat stress using sensor-based monitoring: a wearable approach with environmental ergonomics perspective

Occupational heat stress could impose a greater risk of heat-related morbidities among the exposed users, declining their work productivity and contributing to a financial burden. This necessitate the implementation of adequate preventive measures and control policies to improve the users' well-being and productive capacity. The emergence of modernistic sensors gives rise to workplace heat stress monitoring at a substantially lower cost than expensive conventional equipment. Present work unveils the productive role of sensor-based safety helmet, which could monitor the environmental variables, heat stress indices, and users' physiological variables as an indicator of heat strain. The proposed safety helmet was tested under three different work environments with users' engaged in specific work activities. Notable variations were perceived among the measured data under respective work conditions and physical activity performed. Higher heat risk exposures were attributable to the outdoor condition compared to indoor work conditions. For wet bulb globe temperature index, strong association (p-value < 0.01) was observed with fighter index of thermal stress (R ²-value = 0.959) followed by discomfort index (R ²-value = 0.899) and heat index (R ²-value = 0.867). Results revealed a rise in measured physiological parameters under the heavy workload activity (shoveling task; outdoor location) followed by hacksaw cutting task (indoor location), while least values were associated with light workload activity (drilling task; indoor location). The proposed design intervention could be considered an effective site-specific solution for monitoring heat stress exposures and keeping exposed users well aware of the prevalent thermal work conditions at the individual level.

Occupational Heat Exposure and Breast Cancer Risk in the MCC-Spain Study

BACKGROUND

Mechanisms linking occupational heat exposure with chronic diseases have been proposed. However, evidence on occupational heat exposure and cancer risk is limited.

METHODS

We evaluated occupational heat exposure and female breast cancer risk in a large Spanish case-control study. We enrolled 1,738 breast cancer cases and 1,910 frequency-matched population controls. A Spanish job-exposure matrix, MatEmEsp, was used to assign estimates of the proportion of workers exposed (P ≥ 25% for at least 1 year) and work time with heat stress (wet bulb globe temperature ISO 7243) for each occupation. We used three exposure indices: ever versus never exposed, lifetime cumulative exposure, and duration of exposure (years). We estimated ORs and 95% confidence intervals (CI), applying a lag period of 5 years and adjusting for potential confounders.

RESULTS

Ever occupational heat exposure was associated with a moderate but statistically significant higher risk of breast cancer (OR 1.22; 95% CI, 1.01-1.46), with significant trends across categories of lifetime cumulative exposure and duration (P _trend = 0.01 and 0.03, respectively). Stronger associations were found for hormone receptor-positive disease (OR ever exposure = 1.38; 95% CI, 1.12-1.67). We found no confounding effects from multiple other common occupational exposures; however, results attenuated with adjustment for occupational detergent exposure.

CONCLUSIONS

This study provides some evidence of an association between occupational heat exposure and female breast cancer risk.

IMPACT

Our results contribute substantially to the scientific literature. Further investigations are needed considering multiple occupational exposures.