Cholinesterase activity depression among California agricultural pesticide applicators

Blood cholinesterase activity levels of farmers in winter and hot season of Mae Taeng District, Chiang Mai Province, Thailand

Organophosphate and carbamate pesticides have been widely used by farmers for crop protection and pest control. Inhibition of acetylcholinesterase (AChE) in erythrocyte and butyrylcholinesterase (BChE) in plasma is the predominant toxic effect of organophosphate and carbamate pesticides. Mae Taeng District, Chiang Mai Province, is one of the large areas of growing vegetables and fruits. Due to their regular exposure to these pesticides, the farmers are affected by this toxicity. The objective of the study was to examine the AChE and the BChE activity levels in the blood of 102 farmers for comparison of exposure in two cropping seasons, winter and hot. Blood samples were collected in December 2013 (winter) and April-June 2014 (hot). A total of 102 farmers joined the study, represented by 76 males (74.5 %) and 26 females (25.5 %). The age of most of the farmers was 53.4 ± 8.7 years. Out of 102, 21 farmers used carbamate pesticides. The results showed that the AChE and the BChE activity levels of all the farmers were 3.27 ± 0.84 Unit/mL and 2.15 ± 0.58 Unit/mL, respectively. The AChE and the BChE activity levels in males were 3.31 ± 0.88 Unit/mL and 1.97 ± 0.60 U/mL, respectively, during winter and 3.27 ± 0.82 Unit/mL and 2.15 ± 0.58 U/mL, respectively, during the hot season, and AChE and the BChE activity levels in females were 3.27 ± 0.82 U/mL and 2.44 ± 0.56 U/mL, respectively, during the hot season. The cholinesterase activity levels, both AChE and BChE, in the male farmers' blood had significant difference between the two seasons, while in the case of the female farmers, there was significant difference in the BChE activity levels, at p < 0.05. The BChE activity level was found to significantly correlate with self-spray (p < 0.05), which implies that the BChE activity decreased when they sprayed by themselves. The cholinesterase activity levels of the present study were lower than those of the other studies, which may be an indication of some chronic effect of exposure to anticholinesterase pesticides. Thus, it is recommended that the use of pesticides be decreased, together with increase in the awareness of the impact of pesticides on health; also recommended is regular monitoring of blood cholinesterase.

Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms

Organophosphorus (OP) insecticides are pest-control agents heavily used worldwide. Unfortunately, they are also well known for the toxic effects that they can trigger in humans. Clinical manifestations of an acute exposure of humans to OP insecticides include a well-defined cholinergic crisis that develops as a result of the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh). Prolonged exposures to levels of OP insecticides that are insufficient to trigger signs of acute intoxication, which are hereafter referred to as subacute exposures, have also been associated with neurological deficits. In particular, epidemiological studies have reported statistically significant correlations between prenatal subacute exposures to OP insecticides, including chlorpyrifos, and neurological deficits that range from cognitive impairments to tremors in childhood. The primary objectives of this article are: (i) to address the short- and long-term neurological issues that have been associated with acute and subacute exposures of humans to OP insecticides, especially early in life (ii) to discuss the translational relevance of animal models of developmental exposure to OP insecticides, and (iii) to review mechanisms that are likely to contribute to the developmental neurotoxicity of OP insecticides. Most of the discussion will be focused on chlorpyrifos, the top-selling OP insecticide in the United States and throughout the world. These points are critical for the identification and development of safe and effective interventions to counter and/or prevent the neurotoxic effects of these chemicals in the developing brain. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

Comparison of neurological health outcomes between two adolescent cohorts exposed to pesticides in Egypt

Pesticide-exposed adolescents may have a higher risk of neurotoxic effects because of their developing brains and bodies. However, only a limited number of studies have addressed this risk among adolescents. The aim of this study was to compare neurological outcomes from two cohorts of Egyptian adolescents working as pesticide applicators. In 2005 and 2009, two cohorts of male adolescents working as pesticide applicators for the cotton crop were recruited from Menoufia Governorate, Egypt. The same application schedule and pesticides were used at both times, including both organophosphorus, and pyrethroid compounds. Participants in both cohorts completed three neurobehavioral tests, health and exposure questionnaires, and medical and neurological screening examinations. In addition, blood samples were collected to measure butyryl cholinesterase (BChE) activity. Pesticide applicators in both cohorts reported more neurological symptoms and signs than non-applicators, particularly among participants in the 2005 cohort (OR ranged from 1.18 to 15.3). Except for one test (Trail Making B), there were no significant differences between either applicators or non-applicators of both cohorts on the neurobehavioral outcome measures (p > 0.05). The 2005 cohort showed greater inhibition of serum BChE activity than the 2009 cohort (p < 0.05). In addition, participants with depressed BChE activity showed more symptoms and signs than others without BChE depression (p < 0.05). Our study is the first to examine the consistency of health outcomes associated with pesticide exposure across two cohorts tested at different times from the same geographical region in rural Egypt. This similar pattern of findings across the two cohorts provides strong evidence of the health impact of exposure of adolescents to pesticides.

A Statewide Evaluation of the California Medical Supervision Program Using Cholinesterase Electronic Laboratory Reporting Data

The California Medical Supervision program is designed to protect workers who regularly mix, load, or apply the highly toxic Category I and II organophosphates and carbamates from overexposure by monitoring cholinesterase (ChE) inhibition in plasma and red blood cells. Since January 2011, testing laboratories are required to report test results electronically to the California Department of Pesticide Regulation who shares it with the Office of Environmental Health Hazard Assessment for evaluation. The purpose of this study is to assess the utility of this reporting in evaluating the effectiveness of the Program for illness surveillance and prevention. From 2011 to 2013, we received more than 90 000 test results. Despite data gaps and data quality issues, we were able to perform spatial and temporal analyses and developed a screening tool to identify individuals potentially at risk of overexposure. The data analysis provided some evidence that the Program is effective in protecting agricultural workers handling the most toxic ChE-inhibiting pesticides even though it also identified some areas of potential concerns with individuals that appeared lacking corrective actions in the workplace in response to excessive ChE depressions and parts of the state with disproportionately at-risk individuals. However, changes to the electronic reporting are needed to more accurately identify tests related to the Program and therefore improve the utility of the data received. Moreover, data analysis also revealed that electronic reporting has its limitation in evaluating the Program.

Spatial learning impairment in prepubertal guinea pigs prenatally exposed to the organophosphorus pesticide chlorpyrifos: Toxicological implications

Exposure of the developing brain to chlorpyrifos (CPF), an organophosphorus (OP) pesticide used extensively in agriculture worldwide, has been associated with increased prevalence of cognitive deficits in children, particularly boys. The present study was designed to test the hypothesis that cognitive deficits induced by prenatal exposure to sub-acute doses of CPF can be reproduced in precocial small species. To address this hypothesis, pregnant guinea pigs were injected daily with CPF (25mg/kg,s.c.) or vehicle (peanut oil) for 10days starting on presumed gestation day (GD) 53-55. Offspring were born around GD 65, weaned on postnatal day (PND) 20, and subjected to behavioral tests starting around PND 30. On the day of birth, butyrylcholinesterase (BuChE), an OP bioscavenger used as a biomarker of OP exposures, and acetylcholinesterase (AChE), a major molecular target of OP compounds, were significantly inhibited in the blood of CPF-exposed offspring. In their brains, BuChE, but not AChE, was significantly inhibited. Prenatal CPF exposure had no significant effect on locomotor activity or on locomotor habituation, a form of non-associative memory assessed in open fields. Spatial navigation in the Morris water maze (MWM) was found to be sexually dimorphic among guinea pigs, with males outperforming females. Prenatal CPF exposure impaired spatial learning more significantly among male than female guinea pigs and, consequently, reduced the sexual dimorphism of the task. The results presented here, which strongly support the test hypothesis, reveal that the guinea pig is a valuable animal model for preclinical assessment of the developmental neurotoxicity of OP pesticides. These findings are far reaching as they lay the groundwork for future studies aimed at identifying therapeutic interventions to treat and/or prevent the neurotoxic effects of CPF in the developing brain.

Assessment of acetylcholinesterase and butyrylcholinesterase activities in blood plasma of agriculture workers

Background:

Cholinesterase determination indicates whether the person has been under pesticide exposure is not. It is recommended that the worker′s cholinesterase level should be assessed for workers at a pesticide applied region. Hence, cholinesterase activities in blood samples of agricultural workers exposed to vegetables and grape cultivation with age matched, unexposed workers, who never had any exposure to pesticides, were estimated.

Methods:

The detailed occupational history and lifestyle characters were obtained by questionnaire. Cholinesterase activity was determined by the method of Ellman as modified by Chambers and Chambers.

Results:

AChE was ranging from 1.65 to 3.54μmoles/min/ml in exposed subjects where as it was ranged from 2.22 to 3.51μmoles/min/ml in control subjects. BChE activity was ranging from 0.16 to 5.2μmoles/min/ml among exposed subjects, where as it was ranged from 2.19 to 5.06μmoles/min/ml in control subjects. The results showed statistically significant reduction in enzyme activities (AChE 14%; BChE 56%) among exposed subjects.

Conclusion:

It was concluded that the reduction in cholinesterase activity may lead to varieties of effects. Hence it is compulsory to use protective gadgets during pesticide spray. Further a continuous biomonitoring study is recommended to assess pesticide exposure.

Effects of occupational exposure in pesticide plant on workers' serum and erythrocyte cholinesterase activity

OBJECTIVES

The determination of cholinesterase activity has been commonly applied in the biomonitoring of exposure to organophosphates and carbamates and in the diagnosis of poisoning with anticholinesterase compounds. One of the groups who are at risk of pesticide intoxication are the workers engaged in the production of these chemicals.

AIMS

The aim of this study was to assess the effect of pesticides on erythrocyte and serum cholinesterase activity in workers occupationally exposed to these chemicals.

METHODS

The subjects were 63 workers at a pesticide plant. Blood samples were collected before they were employed (phase I) and after 3 months of working in the plant (phase II). Cholinesterase level in erythrocytes (EChE) was determined using the modified Ellman method, and serum cholinesterase (SChE) by butyrylthiocholine substrate assay.

RESULTS

The mean EChE levels were 48+/-11 IU/g Hb in phase I and 37+/-17 IU/g Hb in phase II (paired t-test, mean=-29; 95% CI=-43-14), p<0.001). The mean SChE level was 9569+/-2496 IU/l in phase I, and 7970+/-2067 IU/l in phase II (paired t-test, mean=1599; 95% CI=1140-2058, p<0.001). There was a significant increase in ALT level (p < 0.001) and a decrease in serum albumin level (p<0.001).

CONCLUSION

In view of the significant decrease in EChE and SChE levels among pesticide workers, it seems that routine assessment of cholinesterase level in workers employed in such occupations and people handling pesticides should be made obligatory.

Toxicity due to organophosphorus compounds: what about chronic exposure?

The inappropriate use of toxic chemicals is common in developing countries, where it leads to excessive exposure and high risks of unintentional poisoning. The risks are particularly high with the pesticides used in agriculture, where poor rural populations live and work in close proximity to these compounds, which are often stored in and around the home. It is estimated that 99% of all deaths from pesticide poisoning occur in developing countries. Whilst the acute toxicity of pesticides has been well documented, there is still relatively little known of the effects on health of chronic pesticide exposure. Organophosphate insecticides have been extensively used in agriculture in developing countries, with little protection for the communities and individuals thus exposed. Given the indisputable chronic exposure of vulnerable groups to organophosphate compounds, including pregnant women, the fetus and young children, the potential for widespread adverse effects is considerable. Thus, whilst there is some evidence that chronic exposure may have adverse effects on health, there is an urgent need for high-quality observational and interventional studies of both occupational and environmental exposure to these compounds.

Fifteen Years of Experience in Cholinesterase Monitoring of Insecticide Applicators

INTRODUCTION

Measuring cholinesterase(ChE) enzyme levels in red blood cells (RBC) and plasma has become a useful tool in the early detection of organophosphate and carbamate poisoning in insecticide handlers. Since 1974 the State of California has required testing of pesticide applicators to prevent disease. This study is a review of the testing experience of two physicians and using one laboratory so that a comparison can be made to previous studies by the author and others.

METHODS

The files of 366 workers who were referred by their employers for ChE activity monitoring were abstracted for patient data, employer identification, and testing data. Results were entered into the EPIINFO program for analysis.

RESULTS

A total of 366 workers from 45 companies were tested over a 15-year period between 1989 and 2004. Most were applicators. There were 690 attempts to establish baselines, of which 545 (79%) were successful. There were 519 monitoring tests on 228 workers, resulting in the removal from exposure of 18 employees, most in 1996. Self-reported exposure history and symptoms resulted in only 3 responses (.6%). The costs were significant ($47,160 total and $36 per test), especially when considering the failure of 145 (21%) employees to establish baselines. There was monthly and yearly variation in plasma and RBC baselines, monthly variance in plasma monitoring tests, and no monthly variance in RBC monitoring. The use of a third baseline test when the first two varied by 15% avoided two false positives. The mean time for recovery from ChE depression was 5.38 weeks.

DISCUSSION

The California ChE monitoring program remains a valuable tool. There was significant monthly and yearly variation in values for both baseline and monitoring plasma and RBC values, with the exception of RBC monthly variance. Self-reported symptoms were not found to be a valuable tool in measuring exposure. Rates of recovery from ChE depression were highly variable. The warning feature of the program was very effective. The costs of monitoring were substantial, but possibly not as great as a single workers' compensation case.

CONCLUSIONS

The California ChE monitoring program serves as a useful and cost-effective means of preventing organophosphate and carbamate overexposure. Elimination of the third baseline test requirement should be considered.

Effectiveness of interventions in reducing pesticide overexposure and poisonings

OBJECTIVE

The objective of this paper was to review the effectiveness of interventions to reduce pesticide overexposure and poisonings in worker populations.

METHODS

We used the Cochrane Collaboration search strategy to search the following databases for articles that tested the effectiveness of interventions in reducing human pesticide exposure or poisonings: MEDLINE, EMBASE, and Occupational Safety and Health (NIOSHTC). Interventions considered included comparisons of pesticide application methods, pesticide mixing methods, worker education, biological monitoring programs, personal protective equipment (PPE) use, pesticide substitutions, and legislation. The outcomes of interest included biological monitoring measures or personal exposure monitoring indicating a reduction of pesticide exposure, observed increased use of PPE, reduction in lost workdays, and where possible, evidence of changes in pesticide poisoning rates as identified by registries and population surveys. Studies were reviewed in depth with special attention to size and study design.

RESULTS

Most studies evaluated exposure during differing configurations of PPE or during different mixing or handling methods. Most studies were small field tests of protective equipment involving less than 20 workers. Some studies examined biological indices of exposure such as cholinesterase or urinary metabolites. Studies showed that PPE was effective in reducing exposure. No controlled studies were found that addressed reducing pesticide poisonings.

CONCLUSIONS

Changes in application procedures, packaging, mixing, use of personal protective equipment, and biological monitoring reduced pesticide exposure under controlled conditions. Cholinesterase monitoring can identify workers with a higher risk of overexposure. Most techniques were not tested in actual worksite programs. Interventions should be examined for their ability to reduce pesticide overexposure in actual working populations. No controlled evaluations of large legislative initiatives were found.

Acute effects of acephate and methamidophos on acetylcholinesterase activity, endocrine system and amino acid concentrations in rats

Acute effects of acephate (Ace) and methamidophos (Met) on acetylcholinesterase activity, endocrine system and amino acid concentrations were studied in rats. The rats were injected intraperitoneally with Ace (500 mg/kg) or Met (5 mg/kg) and then sacrificed at 15 or 60 min after the injection (A15 and A60 for Ace and M15 and M60 for Met). The primary aim of this study was to determine whether the mammalian toxicity of Ace is solely due to its conversion to Met or the protection of Ace against Met-inhibited AChE is also an important factor. The second aim of this study was to study the effects of Ace and Met on the endocrine system and amino acid concentrations and whether or not these effects correlate with AChE inhibition and Met accumulation. The Ace or Met injected animals did not exhibit the signs of organophosphate (OP) poisoning within 15 min after the injection, but exhibited tremors at 45 min after the injection. Blood and brain AChE activity in A15 and M15 rats exhibited 55 to 75% inhibition while the enzyme activity in A60 and M60 rats exhibited 80 to 95% inhibition. Ace was metabolized to Met in rats both in vivo and in vitro. A 5 rats had significantly higher Met concentration in their liver, brain and adrenal glands compared to M 5 rats, and A60 rats had significantly higher Met concentrations in their blood, liver, brain and adrenal glands compared to M60 rats. Thus, tissue Met concentrations in Ace-treated rats were significantly higher than in Met-treated rats and the inhibition of AChE activity was not consistent with the amount of metabolically formed Met, supporting the hypothesis that the Ace protection plays a role in the overall toxicity. Ace and Met both impaired circulating blood hormone and amino acid concentrations in rats. The endocrine effects of Ace and Met differed from their cholinergic effects, and were not proportional to the amount of Met present in different tissues obtained from the treatment groups. Plasma ACTH concentration was elevated in M60 rats but not in A60 rats. Thus, Ace may indirectly protect the pituitary against the toxic effects of Met. Unlike plasma ACTH levels, serum corticosterone and aldosterone levels were elevated in both A60 and M60 rats. Therefore, the effect of Met on the adrenal cortex may be mediated by the pituitary gland, while the effect of Ace may be due to direct Ace-gland interaction. The decrease in the levels of some of the serum amino acids showed an increase in the energy demands in the treatment groups.

Parkinson's disease mortality and pesticide exposure in California 1984-1994

BACKGROUND

In the last two decades reports from different countries emerged associating pesticide and herbicide use with Parkinson's disease (PD). California growers use approximately 250 million pounds of pesticides annually, about a quarter of all pesticides used in the US.

METHODS

We employed a proportional odds mortality design to compare all cases of PD recorded as underlying (1984-1994) or associated causes (1984-1993) of death occurring in California with all deaths from ischaemic heart disease (ICD-9 410-414) during the same period. Based on pesticide use report data we classified California counties into several pesticide use categories. Agricultural census data allowed us to create measures of percentage of land per county treated with pesticides. Employing logistic regression models we estimated the effect of pesticide use controlling for age, gender, race, birthplace, year of deaths, and education.

RESULTS

Mortality from PD as the underlying cause of death was higher in agricultural pesticide-use counties than in non-use counties. A dose response was observed for insecticide use per county land treated when using 1982 agricultural census data, but not for amounts of restricted pesticides used or length of residency in a country prior to death.

CONCLUSIONS

Our data show an increased PD mortality in California counties using agricultural pesticides. Unless all of our measures of county pesticide use are surrogates for other risk factors more prevalent in pesticide use counties, it seems important to target this prevalent exposure in rural California in future studies that use improved case finding mechanisms and collect pesticide exposure data for individuals.

Self reported symptoms and inhibition of acetylcholinesterase activity among Kenyan agricultural workers

OBJECTIVES

This study was part of the East African pesticides project. The general objective was to assess health hazards posed by handling, storage, and use of pesticides, on agricultural estates and small farms with a view to developing strategies for prevention and control of pesticide poisoning. The aim of this paper is to describe the prevalence of symptoms in this population, to relate levels of inhibition to reported symptoms and evaluate at which levels of inhibition symptoms become increased.

METHODS

Complete data were available for 256 exposed subjects and 152 controls from four regions in Kenya. A structured questionnaire on symptoms experienced at the time of interview was given to all subjects and controls. Information was also obtained on sex, age, main occupation, and level of education. Symptoms reported during the high exposure period, were initially clustered in broader symptom categories from reference literature on health effects of pesticides that inhibit cholinesterase (organophosphate and carbamate). Prevalence ratios were estimated for symptoms with changes in cholinesterase activity in serum.

RESULTS

Symptom prevalence in exposed subjects was higher during the high exposure period than the low exposure period, although these differences were not significant. Interestingly, a clear and significant change in symptoms prevalence was found in the controls with a higher prevalence in the low exposure period. Analysis of the relation between cholinesterase inhibition and symptoms showed that prevalence ratios were significantly > 1 for respiratory, eye, and central nervous system symptoms for workers with > 30% inhibition. Similar results were found for analyses with the actual level of acetylcholinesterase activity.

CONCLUSION

The results suggest the presence of a relation between exposure and acetylcholinesterase inhibition, acetylcholinesterase activity, and respiratory, eye, and central nervous system symptoms. Increased symptom prevalence was found at acetylcholinesterase activities generally considered to be non-adverse.

Acetylcholinesterase Inhibition as an Indicator of Organophosphate and Carbamate Poisoning in Kenyan Agricultural Workers

Acetylcholinesterase inhibition was determined for 666 Kenyan agricultural workers; 390 (58.6%) mainly pesticide applicators exposed to organophosphate and carbamate pesticides and 276 (41.4%) unexposed controls from four rural agricultural areas during 1993 and 1994. Baseline levels were depressed in the exposed group (6.1 +/- 0.84; 4.09 +/- 0.84) but not in the unexposed group (5.83 +/- 0.91; 5.60 +/- 0.87). Acetylcholinesterase inhibition was found in all exposed individuals and led, on average, to a decrease of baseline acetylcholinesterase levels of 33% (+/-12%). The control groups had a nonsignificant decrease of only 4% (+/- 8%). The exposed subjects in Naivasha (flower growers) had the largest inhibition (36%), followed by Homabay (cotton growers) (35%) and Wundanyi (vegetable growers) (33%). Those in Migori (tobacco growers) had, by far, the least inhibition of acetylcholinesterase activity (26%), indicating inherent factors that led to less inhibition. Acetylcholinesterase activity levels of 115 exposed individuals (29.6%) and no controls were depressed to values below 60% of baseline levels. The dramatic inhibition observed could lead to chronic clinical and subclinical intoxication. These findings show that acetylcholinesterase inhibition can be used as an indicator of organophosphate and carbamate poisoning in occupationally exposed agricultural workers. There is, therefore, an urgent need for primary prevention programs to monitor and address occupational exposures to these hazardous substances in agriculture in Kenya and other developing countries, as well as to use integrated pest management strategies in crop protection.

Biomarkers of human exposure to pesticides

For centuries, several hundred pesticides have been used to control insects. These pesticides differ greatly in their mode of action, uptake by the body, metabolism, elimination from the body, and toxicity to humans. Potential exposure from the environment can be estimated by environmental monitoring. Actual exposure (uptake) is measured by the biological monitoring of human tissues and body fluids. Biomarkers are used to detect the effects of pesticides before adverse clinical health effects occur. Pesticides and their metabolites are measured in biological samples, serum, fat, urine, blood, or breast milk by the usual analytical techniques. Biochemical responses to environmental chemicals provide a measure of toxic effect. A widely used biochemical biomarker, cholinesterase depression, measures exposure to organophosphorus insecticides. Techniques that measure DNA damage (e.g., detection of DNA adducts) provide a powerful tool in measuring environmental effects. Adducts to hemoglobin have been detected with several pesticides. Determination of chromosomal aberration rates in cultured lymphocytes is an established method of monitoring populations occupationally or environmentally exposed to known or suspected mutagenic-carcinogenic agents. There are several studies on the cytogenetic effects of work with pesticide formulations. The majority of these studies report increases in the frequency of chromosomal aberrations and/or sister chromatid exchanges among the exposed workers. Biomarkers will have a major impact on the study of environmental risk factors. The basic aim of scientists exploring these issues is to determine the nature and consequences of genetic change or variation, with the ultimate purpose of predicting or preventing disease.

Temporary variations in chromosomal aberrations in a group of agricultural workers exposed to pesticides

The induction of chromosomal aberrations (CA) was studied in the peripheral lymphocytes of 29 male agricultural workers occupationally exposed to several pesticides. To investigate possible exposure-related changes in the frequency of CA, a longitudinal study has been conducted. Two blood samples were taken from each individual: one in a period of high exposure (spring-summer) and the other in a period of lower exposure (autumn-winter). Simultaneously, two matched control groups constituted by 29 and 24 healthy men, without indication of exposure to pesticides, were analysed. During the period of major exposure, the group of agricultural workers showed a significant increase in the frequency of CA, mainly of chromatid-type, when compared to the unexposed control group; nevertheless, this increase in the expression of CA was not found in the period of minor exposure. This finding could indicate that the frequency of CA is related to the intensity of the pesticide exposure, and that CA have a relatively short-life, recovering the control value a few months later. In addition to the cytogenetic analysis, biochemical and haemotological blood parameters were also analysed and no significant variations were detected.

Determinants of disability in illnesses related to agricultural use of organophosphates (OPs) in California

Organophosphate (OP)-related illness data reported to the Worker Health and Safety Branch (WH&S) at the California Department of Food and Agriculture (CDFA, now Cal-EPA) in the years 1984-1988 were examined. Eight hundred and seventy-eight cases with systemic illness and 199 cases of skin disease or eye injury were identified. Systemic cases were divided into two outcome groups: (1) "severe," disability and/or hospitalization days (n = 361), and (2) "mild," no disability or hospitalization days (n = 372). For the remainder (n = 145) or 16.5% of the cases, illness severity could not be determined. Using multiple logistic regression, independent predictors of "severe" illness were identified among the systemic cases. Workers coming in contact with OP residue on commodities or in the field ("exposed to residue" or ER) (OR = 4.6, 95% CI = 3.03-7.07) and mixer/loaders/applicators (MLA) (OR = 4.1, 95% CI = 2.72-6.07) were at significantly increased risk of severe illness when compared with cases exposed to OP application drift. Cases with a Spanish surname were also at increased risk of severe illness (OR = 1.8, 95% CI = 1.25-2.73). Increased numbers of OPs per exposure were also associated with severe illness (p < 0.001). Among cases who were exposed to only one OP, severe systemic cases were more likely than mild systemic cases to be associated with exposure to diethyl than dimethyl compounds (OR = 1.6, 95% CI = 1.09-2.38). Severe systemic cases were also more likely than severe skin/eye cases to be associated with exposure to OPs with high toxicity (OR = 5.5, 95% CI = 2.42-12.60) and with exposure to diethyl groups (OR = 4.8, 95% CI = 1.90-12.00). These findings suggest that reducing exposure to OP residues, to OPs with diethyl groups, and to multiple OPs, and exposure during mixer/loader/applicator activities would reduce the risk of OP-related illness.

A multiyear study of blood cholinesterase activity in urban pesticide applicators

This article is a review of blood cholinesterase activity in a cohort of urban pesticide applicators ranging from 1680 to over 3800 workers. During the period 1981-1991, 208, 788 blood samples were taken for measurement of cholinesterase activity with an average of 6 samples per year from each worker. A total of 150 workers or 0.44% of the cohort was removed from exposure to cholinesterase-inhibiting insecticides because of decreased cholinesterase activity. No worker required treatment for signs of cholinesterase inhibition.

Investigation of a fatality among parathion applicators in California

Staff of the California Department of Health Services investigated the death of a parathion applicator in California that was thought to be pesticide-related. A crew of eleven workers (including six sprayers, three mixer/loaders, one mixer/sprayer and one foreman) had been applying 0.125% parathion spray to almond orchards for approximately three weeks. On the day of the fatality, a sprayer rapidly developed symptoms of salivation, sweating, and convulsions after a half-day of work. Despite aggressive medical treatment, the worker died within one hour of his initial symptoms. Significant laboratory results for the decreased case included: parathion residue on the inner and outer garments worn by the worker, parathion in the post-mortem gastric contents, and elevated urinary metabolites consistent with acute parathion intoxication. Interviews with the work crew revealed that three of the 10 workers had complaints of headaches, vomiting, and/or sore throat; yet, subsequent plasma and red cell cholinesterase tests of the co-workers did not show any significant depressions in comparison with pre-season baseline values. This worker death is consistent with prior reports of parathion-related sprayer/applicator intoxications and is the first worker-related parathion death in California since 1972. Substitution of pesticides with less toxic active ingredients or the elimination of parathion is recommended.