Determinants of butyrylcholinesterase inhibition among agricultural pesticide handlers in Washington State: an update

Toxic-Induced Nonthyroidal Illness Syndrome Induced by Acute Low-Dose Pesticides Exposure-Preliminary In Vivo Study

BACKGROUND AND OBJECTIVES

Conditions such as trauma, burns, sepsis, or acute intoxications have considerable consequences on the endocrine status, causing "sick euthyroid syndrome". Organophosphate exposure may induce an increase in acetylcholine levels, thus altering the thyroid's hormonal status. The present study aims to identify the effects of acetylcholinesterase inhibition on thyroid hormones.

MATERIAL AND METHODS

A prospective experimental study was conducted on twenty Wistar rats. Blood samples were drawn to set baseline values for thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4). Chlorpyrifos 0.1 mg/kg was administered by oral gavage to induce acetyl-cholinesterase inhibition. After exhibiting cholinergic symptoms, blood samples were collected to assess levels of cholinesterase and thyroid hormones using ELISA.

RESULTS

Butyrylcholinesterase levels confirmed major inhibition immediately after intoxication compared to the baseline, certifying the intoxication. A significant increase in T4 levels was noted (p = 0.01) both at 2 h and 48 h after administration of organophosphate in sample rats. Similarly, T3 almost doubled its value 2 h after poisoning (4.2 ng/mL versus 2.5 ng/mL at baseline). Surprisingly, TSH displayed acute elevation with an afterward slow descending trend at 48 h (p = 0.1), reaching baseline value.

CONCLUSIONS

This study demonstrated that cholinesterase inhibition caused major alterations in thyroid hormone levels, which may be characterized by a transient hypothyroidism status with an impact on survival prognosis.

Time after a peak-pesticide use period and neurobehavior among ecuadorian children and adolescents: The ESPINA study

BACKGROUND

Limited evidence exists regarding transient neurobehavioral alterations associated with episodic pesticide exposures or agricultural pesticide spray periods. We previously observed that children examined soon after a pesticide spray period (the Mother's Day flower harvest [MDH]) had lower neurobehavioral performance than children examined later. The present study builds on our previous work by incorporating longitudinal analyses from childhood through adolescence.

METHODS

We examined participants in agricultural communities in Ecuador (ESPINA study) during three periods: July-August 2008 (N = 313, 4-9-year-olds); April 2016 (N = 330, 11-17-year-olds); July-October 2016 (N = 535, 11-17-year-olds). Participants were examined primarily during a period of low floricultural production. Neurobehavior was assessed using the NEPSY-II (domains: Attention/Inhibitory Control, Language, Memory/Learning, Visuospatial Processing, and Social Perception). Linear regression and generalized linear mixed models were used to examine cross-sectional and longitudinal associations between examination date (days) after the MDH and neurobehavioral outcomes, adjusting for demographic, anthropometric, and socio-economic variables.

RESULTS

Participants were examined between 63 and 171 days after the MDH. Mean neurobehavioral domain scores ranged from 1.0 to 17.0 (SDrange = 2.1-3.1) in 2008 and 1.0 to 15.5 (SDrange = 2.0-2.3) in 2016. In cross-sectional analyses (2016 only; N = 523), we found significant or borderline positive associations between time after the MDH and Attention/Inhibitory Control (difference/10 days [β] = 0.22 points [95% CI = 0.03, 0.41]) and Language (β = 0.16 points [95% CI = -0.03, 0.34]). We also observed positive, longitudinal associations (2008-2016) with Attention/Inhibitory Control (β = 0.19 points [95% CI = 0.04, 0.34]) through 112 days after the harvest and Visuospatial Processing (β = 3.56, β-quadratic = -0.19 [95% CI: -0.29, -0.09]) through 92 days.

CONCLUSIONS

Children examined sooner after the harvest had lower neurobehavioral performance compared to children examined later, suggesting that peak pesticide spray seasons may transiently affect neurobehavior followed by recovery during low pesticide-use periods. Reduction of pesticide exposure potential for children during peak pesticide-use periods is advised.

Statewide Evaluation of the California Medical Supervision Program Using Cholinesterase Electronic Laboratory Reporting Data: An Update

The California Medical Supervision Program is designed to protect agricultural workers from overexposure to Toxicity Category I and II organophosphate (OP) and carbamate (CB) pesticides by routinely monitoring their blood cholinesterase (ChE) activity levels. ChE testing is conducted at State-approved laboratories and electronically reported to the Department of Pesticide Regulation (DPR) and the Office of Environmental Health Hazard Assessment (OEHHA) for review. In 2015, OEHHA and DPR evaluated the effectiveness of the Program by analyzing ChE data from pesticide handlers performed between 2011 and 2013, which revealed issues with the data quality that hindered the evaluation process. Several interventions have been implemented since then to improve data quality and the overall function of the Program. A new evaluation was conducted in 2020 to 2021 using data from 2014 to 2019 to determine the effectiveness of the Program, Program compliance, and efficacy of the interventions. The analysis revealed similar data quality issues identified in the last evaluation, however, an improvement in data quality was observed. The number of individuals with ChE depression below the action level threshold have decreased in recent years, corresponding to the implementation of certain interventions, indicating that the effectiveness of the Program has improved. Spatial and temporal analysis showed the proportion of pre-exposure baseline tests inversely correlated with pesticide use data while routine follow-up ChE test results showed a positive correlation, indicating a high degree of Program compliance across the state. Major improvements in the data cleaning and analysis since the last evaluation have also improved the evaluation: pesticide handlers under the Program were able to be identified with more certainty and ChE depressions were able to be calculated with increased accuracy. However, further improvements to the data collection process could enhance future evaluations of the Program.

ENDOCRINE DISTURBANCES INDUCED BY LOW-DOSE ORGANOPHOSPHATE EXPOSURE IN MALE WISTAR RATS

BACKGROUND

Organophosphate exposure induces many endocrine effects.

AIM

In this study we observed the effects of acute stress induced by cholinesterase inhibition on the main hormonal axes.

MATERIALS AND METHODS

We included thirteen weanling Wistar rats that were subjected to organophosphate exposure. They were first tested for baseline levels of butyrylcholinesterase, cortisol, free triiodothyronine, thyroxine, thyroid-stimulating hormone and prolactin. Secondly, chlorpyrifos was administered. Next samples were taken to determine the level of all the above-mentioned parameters.

RESULTS

Butyrylcholinesterase was significantly decreased after exposure (p<0.001). Cortisol levels were significantly higher after clorpyrifos administration (358.75±43 vs. 241.2±35 nmoL/L)(p<0.01). Although prolactin had a growing trend (450.25±24.65 vs. 423±43.4 uI/mL), the results were not statistically significant. Both free triiodothyronine and thyroxine were significantly higher after exposure. Surprisingly, thyroid-stimulating hormone level almost doubled after exposure with high statistical significance (p<0.001), suggesting a central stimulation of thyroid axis. Butyrylcholinesterase level was proportional with thyroid-stimulating hormone level (p=0.02) and thyroxine level was inversely correlated to the cortisol level (p=0.01). Acute cholinesterase inhibition may induce high levels of cortisol, free triiodothyronine, thyroxine and thyroid-stimulating hormone. From our knowledge this is the first study dedicated to the assessment of acute changes of hormonal status in weanling animals after low-dose organophosphate exposure.Conclusion. Acute cholinesterase inhibition may cause acute phase hormonal disturbances specific to shocked patients.

Monitoring of the Organophosphate Pesticide Chlorpyrifos in Vegetable Samples from Local Markets in Northern Thailand by Developed Immunoassay

Chlorpyrifos is an organophosphate pesticide that is wildly used among farmers for crop protection. However, there are concerns regarding its contamination in the environment and food chain. In the present study, an in-house indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) specific for detecting chlorpyrifos is developed and validated against gas chromatography–flame photometric detection (GC-FPD) as the conventional method. The developed ic-ELISA was used for detecting chlorpyrifos residue in vegetable samples. The developed ic-ELISA showed good sensitivity to chlorpyrifos at an IC₅₀ of 0.80 µg/kg, with low cross-reactivity to other organophosphate pesticides. The 160 samples were collected from local markets located in the Chiang Rai, Chiang Mai, and Nan provinces in northern Thailand. The positive rate of chlorpyrifos residues in the vegetable samples was 33.8%, with the highest levels found in cucumbers, coriander, and morning glory, at 275, 145, and 35.3 µg/kg, respectively. The highest median levels of chlorpyrifos found in the detected samples were Chinese cabbage (332 μg/kg), cucumber (146.3 μg/kg) and Chinese Kale (26.95 μg/kg). The developed ic-ELISA is suitable for the rapid quantitation of chlorpyrifos residues.

Risk perception and behavior in Egyptian adolescent pesticide applicators: an intervention study

Background

Adolescents are engaged in agricultural work, including pesticide application, around the world. Adolescent pesticide applicators are more likely to be exposed to pesticides than their adult counterparts because of their application practice and hygiene habits surrounding pesticide use. There is a need for low-cost interventions to reduce pesticide exposure. We evaluated a theoretically-based educational intervention to change perceptions about the risk of pesticide use and hygiene habits during and after pesticide application for adolescent and young adult pesticide applicators in Egypt.

Methods

Young adult and adolescent male pesticide applicators were given a one-hour educational intervention to inform them about the risk of pesticide use and how to reduce pesticide exposure. The median age of participants was 18 years old. Changes in perceived susceptibility and effectiveness were measured with a survey pre and post-intervention (n = 119) on the same day. The same survey (n = 95) was given 8-months post-intervention to identify sustained effects. Observational checklists of pesticide application practice were also completed during application seasons before and after the intervention.

Results

There was an increase in the proportion of individuals who viewed pesticides as being a long-term health risk (74.7% pre-intervention to 97.9% post-intervention, McNemar test p < 0.001). This change remained significant when surveyed at the 8-month follow-up (90.5%, p < 0.001). There was also a sustained improvement regarding participants’ views of proper hygiene practice surrounding pesticide application. Applicators were observed wearing goggles, shoes, and masks more frequently post-intervention.

Conclusion

This theoretically-based intervention is an example of a low-cost solution that can improve adolescents’ and young adults’ practices regarding pesticide application and personal hygiene practices during and after pesticide application. The intervention can be applied in other countries with similar safety culture surrounding pesticide application.

Assessment of DNA damage and cholinesterase activity in soybean farmers in southern Brazil: High versus low pesticide exposure

The aim of this study was to evaluate the DNA damage in soybean growers during two agricultural periods of a crop season (high and low exposure) and a control group, as well as butyrylcholinesterase (BChE) activity during these exposure periods in order to estimate the degree of BChE inhibition for the exposed group. DNA damage in peripheral whole blood was evaluated by the comet assay and plasma BChE activity was accessed as a measure of exposure to cholinesterase inhibitors. None of the soybean growers reported using full Personal Protective Equipment (PPE). BChE was lower in high exposure period than in low exposure period and DNA damage index was significantly increased in the high exposure period than in the low exposure period. In addition, DNA damage in both exposure periods was higher than control group. No correlation was found between exposure time and DNA damage and BChE activity. However, negative correlation was observed between DNA damage in high and low exposure periods. The results indicate that soybean growers are exposed to cholinesterase inhibitors and to pesticides mixtures with genotoxic potential.

Blood pressure after a heightened pesticide spray period among children living in agricultural communities in Ecuador

INTRODUCTION

Agricultural pesticide spray periods increase the pesticide exposure potential of children living nearby and growing evidence indicates that they may affect children's health. We examined the association of time following a heightened agricultural production period, the Mother's Day flower harvest (May), with children's blood pressure (BP).

METHODS

We included cross-sectional information of 313 children ages 4-9 years in Ecuadorian agricultural communities (the ESPINA study). Examinations occurred during a period of low flower production, but within 63-100 days (mean = 81.5, SD = 10.9) following the Mother's Day harvest. BP was measured twice using a pediatric sphygmomanometer and BP percentiles appropriate for age, gender and height were calculated.

RESULTS

Participants were 51% male, 1.6% hypertensive and 7.7% had elevated BP. The mean (SD) BP percentiles were: systolic: 51.7 (23.9); diastolic: 33.3 (20.3). There was an inverse relationship between of time after the spray season with percentiles of systolic (difference [β] per 10.9 days after the harvest: -4.3 [95%CI: -6.9, -1.7]) and diastolic BP (β: -7.5 [-9.6, -5.4]) after adjusting for race, heart rate and BMI-for-age z-score. A curvilinear association with diastolic BP was observed. For every 10.9 days that a child was examined sooner after the harvest, the OR of elevated BP/hypertension doubled (OR: 2.0, 95% CI: 1.3, 3.1). Time after the harvest was positively associated with acetylcholinesterase.

CONCLUSIONS

Children examined sooner after a heightened pesticide spray period had higher blood pressure and pesticide exposure markers than children examined later. Further studies with multiple exposure-outcome measures across pesticide spray periods are needed.

Respiratory Condition of Family Farmers Exposed to Pesticides in the State of Rio de Janeiro, Brazil

Pesticide exposure is a growing public health concern. Although Brazil is the world’s largest consumer of pesticides, only a few studies have addressed the health effects among farmers. This study aimed to evaluate whether pesticide exposure is associated with respiratory outcomes among rural workers and relatives in Brazil during the crop and off-seasons. Family farmers (82) were interviewed about occupational history and respiratory symptoms, and cholinesterase tests were conducted in the crop-season. Spirometry was performed during the crop and off-season. Respiratory outcomes were compared between seasons and multiple regressions analysis were conducted to search for associations with exposure indicators. Participants were occupationally and environmentally exposed to multiple pesticides from an early age. During the crop and off-season, respectively, they presented a prevalence of 40% and 30.7% for cough, 30.7% and 24% for nasal allergies, and 24% and 17.3% for chest tightness. Significant associations between spirometry impairments and exposure indicators were found both during the crop and off-season. These findings provide complementary evidence about the association of pesticide exposure with adverse respiratory effects among family farmers in Brazil. This situation requires special attention as it may increase the risk of pulmonary dysfunctions, and the morbidity and mortality burden associated with these diseases.

Chimeric mice with humanized liver as a model for testing organophosphate and carbamate pesticide exposure

BACKGROUND

Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes.

RESULTS

A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose-dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5-day repeated-dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre-dose levels, respectively.

CONCLUSION

Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized-liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pesticide Urinary Metabolites Among Latina Farmworkers and Nonfarmworkers in North Carolina

OBJECTIVES

This paper compares detections and concentrations of pesticide urinary metabolites for Latina farmworkers and nonfarmworkers in North Carolina.

METHODS

Thirty-one farmworkers and 55 nonfarmworkers provided urine samples in 2012 and 2013. Urine samples were analyzed for detections and concentrations of organophosphate insecticide, bis-dithiocarbamate fungicide, and pyrethroid insecticide urinary metabolites.

RESULTS

Detections for several organophosphate and pyrethroid pesticide urinary metabolites were present for substantial proportions of the farmworkers and nonfarmworkers. Concentrations for several of these metabolites were high. Farmworkers and nonfarmworkers were similar in detections and concentrations for the pesticide urinary metabolites included in this analysis.

CONCLUSIONS

Participant pesticide exposure increases health risks for them and their children. Research needs to document pesticide exposure, its health effects, and ways to reduce it. Current information justifies policy development to reduce pesticide exposure in all communities.

Acetylcholinesterase activity and time after a peak pesticide-use period among Ecuadorian children

PURPOSE

Mother's Day (May) is a holiday with substantial demand for flowers, associated with heightened flower production and escalated pesticide use. The effect of spray seasons on pesticide exposures of children living in agricultural communities but who do not work in agriculture is poorly understood. In this study, we estimated the association of time after Mother's Day harvest with children's acetylcholinesterase (AChE) activity. AChE is a physiological marker of organophosphate/carbamate pesticide exposures that may take up to 3 months to normalize after its inhibition.

METHODS

We examined 308 children, aged 4-9 years, in Ecuadorian agricultural communities during a low flower-production season but within 63-100 days (mean: 81.5 days, SD: 10.9) after Mother's Day harvest. We quantified AChE activity (mean: 3.14 U/mL, SD: 0.49) from a single finger-stick sample.

RESULTS

We observed positive linear associations between time after the harvest and AChE among participants living near plantations. The associations were strongest among participants living within 233 m [(0.15 U/mL (95% CI 0.02, 0.28)], slightly weaker among participants living within 234-532 m [0.11 U/mL (0.00, 0.23)], and not associated among participants at greater distances. Similar findings were observed across categories of areas of flower plantations within 500 m of homes.

CONCLUSIONS

These cross-sectional findings suggest that a peak pesticide-use period can decrease AChE activity of children living near plantations. These seasonal pesticide exposures could induce short- and long-term developmental alterations in children. Studies assessing exposures at multiple times in relation to pesticide spray seasons among children who do not work in agriculture are needed.

Longitudinal assessment of occupational determinants of chlorpyrifos exposure in adolescent pesticide workers in Egypt

Chlorpyrifos (CPF) is an organophosphourus insecticide applied to cotton fields by adolescents employed by the Egyptian Ministry of Agriculture. Urinary 3,5,6-trichloro-2-pyridinol (TCPy) is a biomarker of CPF exposure that has substantial variability among these applicators. In order to identify predictors of CPF exposure, we conducted a longitudinal study of 43 adolescent pesticide applicators in Egypt from April 2010 to January 2011 in Egypt. Urinary TCPy was quantified at 25 time-points, prior to, during, and following application. We used log-linear regression and a best subset selection approach to identify the exposure determinants that were most predictive of cumulative TCPy and participants' highest TCPy values (peak exposure). Applicators had cumulative urinary TCPy levels ranging from 167 to 49,8208μg/g creatinine. Total hours applying CPF (semi-partial r²=0.32), and total hours in the field applying other pesticides (semi-partial r²=0.08) were the strongest predictors of cumulative TCPy. Applicators had peak urinary TCPy levels ranging from 4 to 5715μg/g creatinine. The amount of time applying pesticides prior to blood draw was the strongest predictor of peak TCPy (semi-partial r²=0.30). We also observed evidence that wearing clean clothes to work was associated with lower longitudinal TCPy. Our results suggest there is an opportunity for targeted interventions, particularly related to hygiene or implementation of personal protective equipment usage to reduce CPF exposure among adolescent pesticide workers.

Practical Solutions for Pesticide Safety: A Farm and Research Team Participatory Model

Development of the Practical Solutions for Pesticide Safety guide used participatory research strategies to identify and evaluate solutions that reduce pesticide exposures for workers and their families and to disseminate these solutions. Project principles were (1) workplace chemicals belong in the workplace, and (2) pesticide handlers and farm managers are experts, with direct knowledge of production practices. The project's participatory methods were grounded in self-determination theory. Practical solutions were identified and evaluated based on five criteria: practicality, adaptability, health and safety, novelty, and regulatory compliance. Research activities that had more personal contact provided better outcomes. The Expert Working Group, composed of farm managers and pesticide handlers, was key to the identification of solutions, as were farm site visits. Audience participation, hands-on testing, and orchard field trials were particularly effective in the evaluation of potential solutions. Small work groups in a Regional Advisory Committee provided the best direction and guidance for a "user-friendly" translational document that provided evidence-based practical solutions. The "farmer to farmer" format of the guide was endorsed by both the Expert Working Group and the Regional Advisory Committee. Managers and pesticide handlers wanted to share their solutions in order to "help others stay safe," and they appreciated attribution in the guide. The guide is now being used in educational programs across the region. The fundamental concept that farmers and farmworkers are innovators and experts in agricultural production was affirmed by this study. The success of this process demonstrates the value of participatory industrial hygiene in agriculture.

Longitudinal Assessment of Blood Cholinesterase Activities Over 2 Consecutive Years Among Latino Nonfarmworkers and Pesticide-Exposed Farmworkers in North Carolina

OBJECTIVE

This study (1) describes patterns of whole blood total cholinesterase, acetylcholinesterase, and butyrylcholinesterase activities across the agricultural season, comparing farmworkers and nonfarmworkers; and (2) explores differences between farmworkers' and non-farmworkers' likelihood of cholinesterase depression.

METHODS

Blood samples from 210 Latino male farmworkers and 163 Latino workers with no occupational pesticide exposure collected 8 times across 2 agricultural seasons were analyzed. Mean cholinesterase activity levels and depressions 15% or more were compared by month.

RESULTS

Farmworkers had significantly lower total cholinesterase and butyrylcholinesterase activities in July and August and lower acetylcholinesterase activity in August. Farmworkers had significantly greater likelihood of cholinesterase depression for each cholinesterase measure across the agricultural season.

SIGNIFICANCE

A repeated-measures design across 2 years with a nonexposed control group demonstrated anticholinesterase effects in farmworkers. Current regulations designed to prevent pesticide exposure are not effective.