Gliomas and farm pesticide exposure in women: the Upper Midwest Health Study

An excess incidence of brain cancer in male farmers has been noted in several studies, but few studies have focused on women. The National Institute for Occupational Safety and Health Upper Midwest Health Study evaluated effects of rural exposures for 341 female glioma cases and 528 controls, all adult (18-80 years of age) nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. On average, controls lived longer on farms than did cases. After adjusting for age, age group, education, and farm residence, no association with glioma was observed for exposure to arsenicals, benzoic acids, carbamates, chloroacetanilides, dinitroanilines, inorganics, organochlorines, organophosphates, phenoxys, triazines, or urea-based or estrogenic pesticides. An increased risk of glioma was observed for carbamate herbicides but was not statistically significant (odds ratio = 3.0; 95% confidence interval, 0.9-9.5). No association was observed between glioma and exposure to 12 widely used specific pesticides, after adjustment for age, age group, education, and any other pesticide exposure. These results were not affected after exclusion of proxy respondents (43% of cases, 2% of controls). Women were less likely than men to have applied pesticides, but more likely to have laundered pesticide-contaminated clothes. Storing pesticides in the house was associated with a statistically non-significant increased risk. Results show that exposure to pesticides was not associated with an increased risk of intracranial gliomas in women. Other farm-related factors could be etiologic factors and will be discussed in future reports.     

Nonpersistent pesticide exposure self-report versus biomonitoring in farm pesticide applicators

PURPOSE: Few studies using biologic markers to examine nonpersistent pesticide exposure among pesticide applicators were conducted in field settings. This study compares self-reported dermal, inhalation, and ingestion exposures with urinalysis results after one-time application of the commonly used herbicide atrazine to field crops. It was hypothesized that: i) applicator reports of exposure would be associated positively with detection of urinary atrazine metabolites, and ii) applicator reports of personal-protective-equipment (PPE) use would be associated negatively with detection of urinary atrazine metabolites. METHODS: Wisconsin dairy farmers were randomly selected to participate in 1997 to 1998 and were instructed to collect a urine sample 8 hours after the first pesticide application of the season. Farmers then were interviewed within 1 week of their first application to report on application practices. Eighty-six urine samples were analyzed for deethylatrazine, a major atrazine metabolite. RESULTS: Comparing urinalysis results with self-reported dermal, inhalation, and ingestion exposure showed poor agreement between self-reported exposure and urinary deethylatrazine detections (all kappa < 0.40). Multivariate linear regression modeling with deethylatrazine level as the outcome showed that self-reported practices did not significantly predict atrazine metabolite levels. CONCLUSIONS: Possible explanations for the discrepancies between urinalysis results and self-reported data include: i) inaccuracies in self-reported data and ii) substantial interpersonal variation in atrazine metabolism, resulting in major differences in body burden for similar exposures. Either explanation poses challenges for epidemiologic studies of the health effects of pesticides, which rely solely on self-reported measures of exposure. Additional evaluation of determinants of accuracy in self-assessed occupational and environmental exposures is needed.     

Chlorpyrifos exposure in farm families: results from the farm family exposure study

We used urinary biological monitoring to characterize chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridinyl) phosphororthioate) exposure to farm family members from Minnesota and South Carolina who participated in the Farm Family Exposure Study. Five consecutive 24-h urine samples were obtained from 34 families of licensed pesticide applicators 1 day before through 3 days after a chlorpyrifos application. Daily 3,5,6-trichloro-2-pyridinol (TCP) urinary concentrations characterized exposure profiles of the applicator, the spouse, and children aged 4-17 years. Self-reported and observed determinants of exposure were compared to the maximum postapplication TCP concentration. All participants had detectable (> or = 1 microg/l) urinary TCP concentrations at baseline. Applicators' peak TCP levels occurred the day after the application (geometric mean (GM) = 19.0 microg/l). Postapplication TCP change from baseline in the spouses and children was negligible, and the only reliable predictor of exposure was assisting with the application for children aged 12 years and older. The applicators' exposure was primarily influenced by the chemical formulation (GM = 11.3 microg/l for granular and 30.9 microg/l for liquid), and the number of loads applied. Repairing equipment, observed skin contact, and eating during the application were moderately associated TCP levels for those who applied liquid formulations. Estimated absorbed doses (microg chlorpyrifos/kg bodyweight) were calculated based on TCP excretion summed over the 4 postapplication days and corrected for pharmacokinetic recovery. The GM doses were 2.1, 0.7, and 1.0 microg/kg bodyweight for applicators, spouses, and children, respectively. Chlorpyrifos exposure to farm family members from the observed application was largely determined by the extent of contact with the mixing, loading, and application process.     

Urinalysis of atrazine exposure in farm pesticide applicators.

This study compared three relatively common laboratory methods for the detection of atrazine (a triazine herbicide commonly used in US agriculture), and related metabolites in urine. Ninety-nine samples collected from atrazine applicators within 8 h post application were analyzed. Thirty-seven percent of applicators showed detectable levels (minimum = 1.0 ng/ml) of deethylatrazine (an atrazine metabolite typically found in environmental samples) in their urine, based on gas chromatography-mass spectrometry (GC-MS) analysis (mean = 14.2 ng/ml). Fifty applicator samples were tested using an enzyme-linked immunosorbent assay (ELISA) designed for the mercapturate metabolic product. Most of these samples (80%) had detectable levels of the mercapturate product. A triazine in water ELISA was also used to test several diluted urine samples from atrazine applicators, and all samples were positive for triazines. Mediocre agreements between the three methods indicated that each detected distinct atrazine exposure products. The results indicate that single field applications of atrazine result in measurable pesticide doses to applicators and that the choice of field assay should depend on the exposure product to be evaluated.     

Urinary biomarkers of atrazine exposure among farm pesticide applicators

PURPOSE: This study assessed the feasibility of three laboratory methods for the detection of atrazine, a triazine herbicide, and its related metabolites in urine collected from field applicators.METHODS: Urine samples were collected from 256 randomly sampled field applicators 8 hours post application. Of these, 99 reported atrazine use during the application prior to sample collection and these samples were subsequently analyzed for urinary biomarkers.RESULTS: 37.4% (n = 37) samples showed detectable levels (minimum = 1.0 ng/mL) of deethylatrazine using gas chromatographic mass spectrometry (GCMS) analysis (X = 14.2 ng/mL; s.d. = 13.5). Fifty samples were tested using atrazine mercapturate in urine ELISA methods and 80% (n = 40) of these samples showed detectable levels of atrazine (X = 6.4 ng/mL; s.d. = 7.5). Of 10 samples tested by triazines in water ELISA methods, a common assay used for the detection of atrazine in groundwater, 100% showed detectable levels of atrazine (X = 22.4 ng/mL; s.d. = 13.9). Of the 21 samples collected from non-applicators and tested by GCMS, none evidenced detectable atrazine levels. Using GCMS as the gold standard, analyses showed that the mercapturate in urine ELISA was 48% sensitive and 91% specific whereas the triazines in water ELISA was 69% sensitive and 100% specific.CONCLUSIONS: It is possible to detect one-time atrazine exposures through analysis of urinary biomarkers among pesticide applicators. The feasibility of triazines in water ELISA methods for use in field studies for analyzing the presence of atrazine and related metabolites in urine was supported, but these methods need further testing on larger applicator samples before they can be used for standard screening.     

Oxidative stress in the blood of farm workers following intensive pesticide exposure

The aim of this study was to evaluate oxidative stress in workers who formulate organophosphate, synthetic pyrethroid and carbamate pesticides. In this survey, blood erythrocytes from a group of 94 pesticide-formulating workers (at least 5-years experience in pest-control in apple and cherry production) and 45 control subjects were examined for oxidative stress parameters. The control group was composed of 45 healthy people living in the same region with no exposure to pesticides. Lipid peroxidation level, catalase, superoxide dismutase and glutathione peroxidase activities in erythrocytes were analysed as biomarkers of oxidative stress. In addition, the acetylcholinesterase activity was measured as a biomarker of toxicity. Results indicated that chronic exposure to organophosphate, synthetic pyrethroid and carbamate pesticides were associated with increased activities of catalase, SOD and lipid peroxidation in erythrocytes (p < 0.05). Acetylcholinesterase activity did not show any significant differences between the two groups (p > 0.05). It is concluded that human chronic exposure to pesticides may result in stimulated antioxidant enzymes.     

Chlorothalonil exposure and cancer incidence among pesticide applicator participants in the agricultural health study

Background

Chlorothalonil is a broad spectrum, non-systemic fungicide widely used to control diseases affecting over 50 fruit, vegetable, and agricultural crops. Despite its extensive use for over 30 years, little is known about the potential human carcinogenicity associated with the routine application of chlorothalonil. Rodent studies have shown evidence of renal tubular carcinomas and adenomas. We explored cancer incidence with chlorothalonil exposure using data from the Agricultural Health Study, a prospective cohort of licensed pesticide applicators in Iowa and North Carolina.

Methods

Licensed private and commercial pesticide applicators were recruited into this study from 1993 to 1997. Detailed information regarding pesticide use was obtained via self-administered questionnaires. Cancer incidence was followed through December 31, 2004. Chlorothalonil exposure was classified by lifetime exposure days and intensity-weighted lifetime exposure days, and then categorized into tertiles. The intensity-weighted lifetime exposure days metric was calculated based on a complex algorithm which includes pesticide application methods among other factors. This may increase or decrease exposure.

Results

Of the 47,625 pesticide applicators included in this analysis, 3657 applicators reported using chlorothalonil with a median of 3.5 application days per year. Chlorothalonil was not associated with overall cancer incidence, nor did we find any association with colon, lung, and prostate cancers—the only cancers for which we had sufficient numbers to explore associations.

Conclusion

We did not find any strong evidence for an association between chlorothalonil and the cancers investigated. Although animal studies have suggested renal cancer may be associated with chlorothalonil, we had insufficient data to evaluate this cancer.     

A review of pesticide exposure and cancer incidence in the agricultural health study cohort

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort. Studies were identified from the AHS publication list available on a Medline/PubMed database search in March 2009. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposure-response relationships. Most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios and positive exposure-response patterns were reported for 12 pesticides currently registered in Canada and/or the United States. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposure-response patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed six pesticides. Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.     

Adult leukemia and farm practices: an alternative approach for assessing geographical pesticide exposure

Many studies have attempted to show a significant relationship between leukemia and farm practices, and some of them mention the potential responsibility of pesticide exposure. In this study, a pesticide exposure index (PEI) is established for geographical units at a small scale. It measures, as accurately as possible, the exposure of the farming population to pesticides, taking into account differential practices in the treatment of different crops as well as an estimate of the time per inhabitant spent cultivating each crop. This approach was developed in southern Normandy, an area of France exhibiting strong contrasts of agricultural activities, and where the necessary agricultural surveys at a small geographical level were available. Statistically significant increasing trends between leukemia mortality of males over 15 on one hand and the PEI and the proportion of agricultural land growing cereals on the other hand were found.     

Reducing pesticide exposure and associated neurotoxic burden in an Ecuadorian small farm population

The contribution of community-based interventions, including farmer field schools (FFSs) in integrated pest management (IPM), to reducing pesticide exposures and associated neurotoxic burden among small-farm families in Ecuador was assessed in three Andean farming communities in a co-design of targeted action-research. Baseline questionnaire surveys elicited pesticide-related knowledge, practices, and exposure and neurobehavioral assessments were done using an adapted WHO battery. Pesticide applications on plots farmed by FFS versus non-FFS participants were compared. A year later, repeated surveys of participating households (n = 29) and neurobehavioral testing of individuals (n = 63) permitted comparisons of pre- and post-intervention values. The FFS graduates applied pesticides on their plots less frequently (p = 0.171). FFS households had increased pesticide-related knowledge of labels and exposure risk factors (both p < 0.004), better pesticide-handling practices (p < 0.01), and less skin exposure (p < 0.01). Neurobehavioural status had improved, particularly digit span and visuo-spatial function, resulting in overall z-score increases. Thus, community interventions reduced pesticide use, reported skin exposure, and neurotoxic burden among smallholder farm families.     

Literature review: dermal monitoring data for pesticide exposure assessment of farm workers

Objective: To conduct a literature review to determine the types of information that existing dermal pesticide monitoring data could provide for future pesticide exposure assessment in occupational epidemiology.

Methods: A systematic literature search was performed on eight online databases. Two screening phases with predetermined criteria identified the qualifying literature. Standard information and dermal pesticide monitoring data were recorded and summarized from each qualifying study to assess its usefulness for future pesticide exposure assessment.

Results: A total of 31 farm studies qualified for review; task information was used to standardize all farm job(s) evaluated into 5 job groups: operators, applicators, mixer-loaders, field workers, and flaggers. When attempting to compare dermal exposure levels between studies, two types of variation were identified: (1) variation in study focus and reporting and 2) variation in exposure levels. The former variation type prevented exposure level comparisons between studies. Within studies, exposure levels were compared across body parts to identify that which had the highest measured exposure and to determine if results were similar in other studies that evaluated the same farm job. Using studies that measured exposure for multiple farm jobs, within study comparisons of total body exposure were performed to evaluate work factors.

Conclusion: Future dermal pesticide exposure monitoring studies should standardize reporting procedures, as suggested in this review, to allow for more extensive dermal data comparisons. Body parts with highest measured levels of dermal exposure were identified by farm job, along with work factors to be further investigated as potential dermal pesticide exposure determinants for farm workers.     

An updated algorithm for estimation of pesticide exposure intensity in the agricultural health study

An algorithm developed to estimate pesticide exposure intensity for use in epidemiologic analyses was revised based on data from two exposure monitoring studies. In the first study, we estimated relative exposure intensity based on the results of measurements taken during the application of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) (n = 88) and the insecticide chlorpyrifos (n = 17). Modifications to the algorithm weighting factors were based on geometric means (GM) of post-application urine concentrations for applicators grouped by application method and use of chemically-resistant (CR) gloves. Measurement data from a second study were also used to evaluate relative exposure levels associated with airblast as compared to hand spray application methods. Algorithm modifications included an increase in the exposure reduction factor for use of CR gloves from 40% to 60%, an increase in the application method weight for boom spray relative to in-furrow and for air blast relative to hand spray, and a decrease in the weight for mixing relative to the new weights assigned for application methods. The weighting factors for the revised algorithm now incorporate exposure measurements taken on Agricultural Health Study (AHS) participants for the application methods and personal protective equipment (PPE) commonly reported by study participants.     

Variation in yearly residential radon concentrations in the upper midwest

It is well known that inhalation of 222Rn and 222Rn decay products increases the risk of lung cancer. While the occurrences of high radon areas in the United States are generally known, studies examining the temporal yearly radon variation in homes across different regions are lacking. This information is essential to assess the ability of a year-long radon measurement to predict the future radon concentration in a home or reconstruct the retrospective residential radon concentration. The purpose of this study is to help fill this gap by examining the temporal variation of residential radon concentrations in homes over several years as well as to explore factors that affect the yearly temporal variability of residential radon concentrations. The coefficient of variation was used as a measure of relative variation between multiple measurements performed across homes over several years. Generalized linear model analyses were applied to investigate factors affecting the coefficient of variation. The median coefficient of variation between the first and second test period was 12%, while a median coefficient of variation of 19% was found between the first and third test period. Factors impacting the coefficients of variation were found to vary for different types of homes and by floors of a home. This study provides important insights into the uncertainty of residential radon gas concentrations that can be incorporated into the sensitivity analyses for the risk estimates of both the North American and global pooling of residential radon studies to improve risk estimates.     

HIV/AIDS knowledge among female migrant farm workers in the midwest

The rate of HIV infection in the migrant farm worker community is 10 times the national average. A survey was conducted of 106 female migrant farm workers in rural Northwest Ohio to assess HIV knowledge. The average participant's age was 28.7 years, 78 spoke Spanish, and 47 had an 8th- grade education. Fifty-six women received their information on HIV/AIDS from television. Eighty-seven women identified sexual contact as the major source of HIV transmission and 54 women identified the combination of sex, use of needles, and blood contact as the important routes. Sixty-nine women identified both homosexual and heterosexual intercourse as risk factors. Only 58 women identified perinatal infection as a route of HIV transmission and 59 women knew that treatment was available to prevent perinatal transmission. Although the majority of women had a good general knowledge of HIV transmission, further prevention education on perinatal transmission is needed among this population.     

Respiratory diseases and pesticide exposure: a case-control study in Lebanon

STUDY OBJECTIVE: To evaluate the odds of being exposed to pesticides in asthmatic adults. DESIGN: A case-control study was performed in Lebanon. SETTING: People were approached when consulting physicians as outpatients. PATIENTS: Asthmatic patients and non-asthmatic controls in several Lebanese hospitals were interviewed. MAIN RESULTS: The study included 407 subjects from 10 medical centres. Any exposure to pesticides was associated to asthma (OR = 2.11 (1.47 to 3.02); p<10(-4)). Occupational use presented the highest association (OR = 4.98 (1.07 to 23.28); p = 0.02), followed by regional exposure (OR 3.51 (2.11 to 5.85); p<10(-4)). Results were confirmed by multivariate analysis, particularly for regional exposure (OR(a) = 2.78; p = 0.02) and house exposure (OR(a) = 2.17; p = 0.001). CONCLUSIONS: Results are comparable to those found in other studies; especially for occupational exposure. Pesticides toxicological effects may explain chronic respiratory symptoms and asthma associations found with all exposure types. Pesticide exposure was associated with asthma in Lebanese adults.     

Field study on exposure and health effects of an organophosphate pesticide for maintaining registration in the Philippines

To support the continued use and the registration of monocrotophos, a field study was conducted at Calauan, Laguna, The Philippines, to assess exposure and the resulting health risk to 21 spraymen applying monocrotophos to rice crop by knapsack spraying during 3 consecutive days. The findings of the study were as follows: exposure of uncovered hands and of the skin of the back to the concentrate was visually observed during the filling, and respectively loading operations; During spraying exposure from airborne diluted formulation occurred; in addition contamination of the lower parts of the body took place because of direct contact with the sprayed crop; Determination of the amount of the urinary metabolite dimethylphosphate excreted in 24 hours urine samples demonstrated absorption of monocrotophos into the body of the spraymen. The half-life of elimination of the urinary metabolite from the body was on average 18 hours; No clinically significant inhibitions of whole blood or red blood cell cholinesterase activities were found, i.e., 30% below baseline values. However, 8 of 21 spraymen had plasma cholinesterase levels below 50% of baseline values;--No acute adverse health effects associated with the application of monocrotophos were observed, which was in accordance with the absence of clinically significant cholinesterase depressions. The conclusion of the study was that the use of monocrotophos under prevailing typical conditions in the Philippines, which varies from a frequency of one application per season to a maximum of 3 applications each on 3 consecutive days per week, and where label safety instructions are not necessarily observed, is not expected to pose an acute health risk under the prevailing conditions and practices, which includes filling, spraying and cleaning activities. From the experience in this study it is clear that proper spraying technique and adequate use of personal protection will significantly reduce exposure. As such a reduction is highly recommendable, advice on proper spray procedures and adequate personal protection has been reinforced.     

Organophosphate pesticide exposure and attention in young Mexican-American children: the CHAMACOS study

Background

Exposure to organophosphate (OP) pesticides, well-known neurotoxicants, has been associated with neurobehavioral deficits in children.

Objectives

We investigated whether OP exposure, as measured by urinary dialkyl phosphate (DAP) metabolites in pregnant women and their children, was associated with attention-related outcomes among Mexican-American children living in an agricultural region of California.

Methods

Children were assessed at ages 3.5 years (n = 331) and 5 years (n = 323). Mothers completed the Child Behavior Checklist (CBCL). We administered the NEPSY-II visual attention subtest to children at 3.5 years and Conners’ Kiddie Continuous Performance Test (K-CPT) at 5 years. The K-CPT yielded a standardized attention deficit/hyperactivity disorder (ADHD) Confidence Index score. Psychometricians scored behavior of the 5-year-olds during testing using the Hillside Behavior Rating Scale.

Results

Prenatal DAPs (nanomoles per liter) were nonsignificantly associated with maternal report of attention problems and ADHD at age 3.5 years but were significantly related at age 5 years [CBCL attention problems: β = 0.7 points; 95% confidence interval (CI), 0.2–1.2; ADHD: β = 1.3; 95% CI, 0.4–2.1]. Prenatal DAPs were associated with scores on the K-CPT ADHD Confidence Index > 70th percentile [odds ratio (OR) = 5.1; 95% CI, 1.7–15.7] and with a composite ADHD indicator of the various measures (OR = 3.5; 95% CI, 1.1–10.7). Some outcomes exhibited evidence of effect modification by sex, with associations found only among boys. There was also limited evidence of associations between child DAPs and attention.

Conclusions

In utero DAPs and, to a lesser extent, postnatal DAPs were associated adversely with attention as assessed by maternal report, psychometrician observation, and direct assessment. These associations were somewhat stronger at 5 years than at 3.5 years and were stronger in boys.     

Effects of pesticide applications on respiratory health of Ethiopian farm workers

The effects of pesticide use on the respiratory health of agricultural farm workers were studied in 203 farm workers and 131 controls. The farm workers were sprayers, supervisors, technicians, and pest assessors. Pulmonary function was found to be remarkably poor among the non-smoker supervisors, followed by the non-smoker sprayers, as compared with that of the non-smoker controls. The means (SD) of FVC and FEV1 for supervisors and sprayers were 2.88 (0.41), 3.05(0.50) and 2.74(0.38), 2.89(0.54), respectively, p < 0.05. The non-smoker technicians had the most respiratory symptoms, with wheezing and breathlessness being the most frequent (35.7% in 14 technicians). Farm workers with various job experiences are subject to reduction of pulmonary function and frequent complaints of respiratory symptoms that could possibly lead to chronic respiratory health problems.     

Pesticide use by persons who reported a high pesticide exposure event in the agricultural health study

Almost 16% of the pesticide applicators in the Agricultural Health Study (AHS) cohort (a cohort that includes 52,629 private applicators) reported having a high pesticide exposure event (i.e., an incident or experience while using a pesticide that caused an unusually high personal exposure). Pesticides involved in these events were compared to the frequency with which specific pesticides were ever used by the AHS cohort. Generally, pesticides with greater acute toxicity were more frequently involved with the high pesticide exposure event than were other pesticides. Whereas it is clear that the use of acutely toxic pesticides may be related to more frequent visits to health care facilities, the reason that the spills and immersions of the high pesticide exposure events are associated with the acute toxicity of the pesticide is not intuitively clear. This analysis suggests that current practices directed at minimizing pesticide exposures may not be sufficient for acutely toxic or irritating chemicals.