Exposure to atrazine and selected non-persistent pesticides among corn farmers during a growing season

Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Rockville, Maryland 20852-7240, USA.
Journal of Exposure Science and Environmental Epidemiology (Impact Factor: 3.19). 09/2009; 19(6):544-54. DOI: 10.1038/jes.2008.53
Source: PubMed


The aim was to develop quantitative estimates of farmers' pesticide exposure to atrazine and to provide an overview of background levels of selected non-persistent pesticides among corn farmers in a longitudinal molecular epidemiologic study. The study population consisted of 30 Agricultural Health Study farmers from Iowa and 10 non-farming controls. Farmers completed daily and weekly diaries from March to November in 2002 and 2003 on pesticide use and other exposure determinants. Urine samples were collected at 10 time points relative to atrazine application and other farming activities. Pesticide exposure was assessed using urinary metabolites and diaries. The analytical limit of detection (LOD) ranged between 0.1 and 0.2 microg/l for all pesticide analytes except for isazaphos (1.5 microg/l) and diazinon (0.7 microg/l). Farmers had higher geometric mean urinary atrazine mercapturate (AZM) values than controls during planting (1.1 vs <LOD microg/g creatinine; P<0.05). AZM levels among farmers were significantly related to the amount of atrazine applied (P=0.015). Interestingly, farmers had a larger proportion of samples above the LOD than controls even after exclusion of observations with an atrazine application within 7 days before urine collection (38% vs 6%, P<0.0001). A similar pattern was observed for 2,4-D and acetochlor (92% vs 47%, P<0.0001 and 45% vs 4%, P<0.0001, respectively). Urinary AZM levels in farmers were largely driven by recent application of atrazine. Therefore, the amount of atrazine applied is likely to provide valid surrogates of atrazine exposure in epidemiologic studies. Elevated background levels of non-persistent pesticides, especially 2,4-D, indicate importance in epidemiologic studies of capturing pesticide exposures that might not be directly related to the actual application.

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    • "observed urinary traces of atrazine mercapturate similar to our study (6% of detectable levels, with an LOD below 0.2 µg/L) (Bakke et al. 2009). As Barr et al. (2007) "
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    ABSTRACT: Despite evidence of atrazine toxicity in developing organisms from experimental studies, few studies--and fewer epidemiologic investigations--have examined the potential effects of prenatal exposure. We assessed the association between adverse birth outcomes and urinary biomarkers of prenatal atrazine exposure, while taking into account exposures to other herbicides used on corn crops (simazine, alachlor, metolachlor, and acetochlor). This study used a case-cohort design nested in a prospective birth cohort conducted in the Brittany region of France from 2002 through 2006. We collected maternal urine samples to examine pesticide exposure biomarkers before the 19th week of gestation. We found quantifiable levels of atrazine or atrazine mercapturate in urine samples from 5.5% of 579 pregnant women, and dealkylated and identified hydroxylated triazine metabolites in 20% and 40% of samples, respectively. The presence versus absence of quantifiable levels of atrazine or a specific atrazine metabolite was associated with fetal growth restriction [odds ratio (OR) = 1.5; 95% confidence interval (CI), 1.0-2.2] and small head circumference for sex and gestational age (OR = 1.7; 95% CI, 1.0-2.7). Associations with major congenital anomalies were not evident with atrazine or its specific metabolites. Head circumference was inversely associated with the presence of quantifiable urinary metolachlor. This study is the first to assess associations of birth outcomes with multiple urinary biomarkers of exposure to triazine and chloroacetanilide herbicides. Evidence of associations with adverse birth outcomes raises particular concerns for countries where atrazine is still in use.
    Full-text · Article · Mar 2011 · Environmental Health Perspectives
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    • "This assumption of equal exposure intensity , while practical for large cohort studies, may introduce exposure misclassification as exposure intensity is likely to vary among applicators due to differences in their exposure modifying factors. Numerous studies have shown the importance of factors that modify pesticide exposure intensity, such as personal protective equipment (PPE) used, application method, and formulation (de Cock et al., 1998; Stewart et al., 1999; Hines et al., 2001; Arbuckle et al., 2002; Harris et al., 2002; Acquavella et al., 2004; Geer et al., 2004; Alexander et al., 2006, 2007; Baldi et al., 2006; Bakke et al., 2009; Lebailly et al., 2009; Thomas et al., 2010a). Identifying and quantifying the important determinants of exposure for study participants can minimize exposure misclassification by improving the exposure contrast between individuals and by better identifying the highest-exposed individuals. "
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    ABSTRACT: Methods: External exposure metrics included personal air, hand rinse, and dermal patch samples collected from each applicator on 2 days in 2002-2003. A 24-h urine sample was also collected. Exposure determinants were identified for each external metric using multiple linear regression models via the NLMIXED procedure in SAS. The AHS algorithm was adjusted, consistent with the identified determinants. Mixed-effect models were used to evaluate the correlation between the adjusted and unadjusted algorithm and urinary captan metabolite levels. Results: Consistent determinants of captan exposure were a measure of application size (kilogram of captan sprayed or application method), wearing chemical-resistant (CR) gloves and/or a coverall/suit, repairing spray equipment, and product formulation. Application by airblast was associated with a 4- to 5-fold increase in exposure as compared to hand spray. Exposure reduction to the hands, right thigh, and left forearm from wearing CR gloves averaged similar to 80%, to the right and left thighs and right forearm from wearing a coverall/suit by similar to 70%. Applicators using wettable powder formulations had significantly higher air, thigh, and forearm exposures than those using liquid formulations. Application method weights in the AHS algorithm were adjusted to nine for airblast and two for hand spray; protective equipment reduction factors were adjusted to 0.2 (CR gloves), 0.3 (coverall/suit), and 0.1 (both). Conclusions: Adjustment of application method, CR glove, and coverall weights in the AHS algorithm based on our exposure determinant findings substantially improved the correlation between the AHS algorithm and urinary metabolite levels.
    Full-text · Article · Mar 2011 · Annals of Occupational Hygiene
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    • "Several studies have found non significant associations between atrazine exposure and NHL; for example, a study of 36,513 atrazine-exposed pesticide applicators in the U.S. Agricultural Health Study (AHS) demon strated non significant excesses of lung cancer, bladder cancer, NHL, and multiple myeloma (Rusiecki et al. 2004). Follow-up of the AHS cohort through 2006 is now under way and, along with analysis of biomarkers among corn farmers and similar studies in atrazine-exposed women (Bakke et al. 2008; Vermeulen et al. 2005), could shed light on the effects of atrazine. "
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    ABSTRACT: There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans. For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent. Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches. Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation. Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.
    Full-text · Article · Oct 2010 · Environmental Health Perspectives
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