Epidemiologic Studies of Occupational Pesticide Exposure and Cancer Regulatory Risk Assessments and Biologic Plausibility (original) (raw)

Epidemiologic Studies of Occupational Pesticide Exposure and Cancer

Annals of Epidemiology, 2003

Epidemiologic studies frequently show associations between self-reported use of specific pesticides and human cancers. These findings have engendered debate largely on methodologic grounds. However, biologic plausibility is a more fundamental issue that has received only superficial attention. The purpose of this commentary is to review briefly the toxicology and exposure data that are developed as part of the pesticide regulatory process and to discuss the applicability of this data to epidemiologic research. The authors also provide a generic example of how worker pesticide exposures might be estimated and compared to relevant toxicologic dose levels. This example provides guidance for better characterization of exposure and for consideration of biologic plausibility in epidemiologic studies of pesticides.

A Review of Pesticide Exposure and Cancer Incidence in the Agricultural Health Study Cohort

Environmental Health Perspectives, 2010

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort. data sources: Studies were identified from the AHS publication list available at http://aghealth. nci.nih.gov as well as through a Medline/PubMed database search in March 2009. We also examined citation lists. 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. data synthesis: We reviewed 28 studies; most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios (or odds ratios) and positive exposure-response patterns were reported for 12 pesticides currently registered in Canada and/or the United States (alachlor, aldicarb, carbaryl, chlorpyrifos, diazinon, dicamba, S-ethyl-N,N-dipropylthiocarbamate, imazethapyr, metolachlor, pendimethalin, permethrin, trifluralin). However, estimates of association for specific cancers were often imprecise because of small numbers of exposed cases, and clear monotonic exposure-response patterns were not always apparent. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposureresponse 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 for alachlor, carbaryl, metolachlor, pendimethalin, permethrin, and trifluralin. conclusions: Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.

Pesticide exposure and cancer: an integrative literature review

Saúde em Debate

We conducted an integrative literature review of published studies on pesticide and cancer exposure, focusing on farmers, rural population, pesticide applicators, and rural workers. The Medline/PubMed was used as searching database. After the retrieval, 74 articles were selected according to pre-established criteria, which design involved 39 case-controls, 32 cohorts, 2 ecological ones, and 1 cross-sectional. Among them, 64 studies showed associations between pesticides and cancer while 10 did not find any significant association. The studies found 53 different types of pesticides significantly associated with at least one type of cancer and 19 different types of cancers linked to at least one type of pesticide. Although few studies presented contradictory results, the sole fact of being a farmer or living near crops or high agricultural areas have also been used as a proxy for pesticide exposure and significantly associated with higher cancer risk. The literature well illustrates t...

Health Impacts of Pesticide Exposure in a Cohort of Outdoor Workers

Environmental Health Perspectives, 2003

The widespread use of synthetic chemicals after the Second World War has revolutionized agricultural practice. Initial studies of the possible health effects of these substances on humans were small and reassuring (Cameron and Burgess 1945; Hayes and Durham 1956). During the 1960s, however, it became evident that persistent pesticides were having an adverse impact on ecologic communities (Ramade 1987; Ratcliffe 1970). This led to a number of more extensive epidemiologic investigations exploring the possible impact of these exposures on human health [International Agency for Research on Cancer (IARC) 1991; Pearce and Reif 1990). These studies faced numerous methodologic problems common to environmental epidemiology, and even today, our understanding of the relationship between pesticides and human health is limited (Blondell 1990). In this paper we describe a historical cohort study undertaken to examine the health outcomes of a group of agricultural workers with high occupational pesticide exposures. The main group investigated in this study comprised all identifiable field staff employed by the New South Wales (NSW), Australia, Board of Tick Control between 1935 and 1995. The board constructed and operated over 1,600 cattle dips in a tick quarantine zone on the east coast of Australia, and over 3,000 staff worked on the program during the study period. Subjects interviewed during the course of the study report extremely high and recurrent exposures to the insecticides used in the dips. This is supported by limited evidence from an occupational monitoring program.

Effects of pesticides on occupationally exposed humans

TheScientificWorld …, 2006

Pesticides are known to contain numerous genotoxic compounds; however, genotoxicity biomonitoring studies of workers occupationally exposed to pesticides have produced variable results. In this study, we employed the comet assay to examine DNA damage in peripheral blood lymphocytes (PBLs) from 64 greenhouse workers from Almería in southeastern Spain in comparison to PBLs from 50 men from the same area, but not engaged in any agricultural work. The results indicated that there were no differences in the basal levels of DNA damage in the two study groups. In addition, exposure of PBL from the workers and controls to hydrogen peroxide or γ-irradiation led to similar levels of DNA damage; the subsequent repair of the induced DNA damage was also similar for both study populations. Smoking had no impact on any of the responses. The results of this study indicate that the greenhouse workers had no detectable increase in DNA damage or alteration in the cellular response to DNA damage compared to our control population.

Exposure to pesticides and the associated human health effects

Science of The Total Environment, 2017

• Pesticides are designed to function with reasonable certainty and minimal risk to human health. • Pesticide exposure is however turned out to be linked with various diseases including cancer. • In light of the significance of pesticide pollution, the general aspects of pesticides are assessed. • The current state of knowledge regarding pesticide use and its detrimental impacts is described.

Could pesticide toxicology studies be more relevant to occupational risk assessment

Annals of Occupational …, 2001

Pesticide toxicology study design has evolved from concern for oral exposure via food residues. The emphasis on the oral route does not generally apply to workers that are exposed primarily via the dermal route either handling pesticides or re-entering treated fields. As a result numerous assumptions about how oral toxicology results relate to dermal exposure must be made when conducting worker risk assessments. These assumptions introduce a high degree of uncertainty. Alternative toxicology study designs are suggested to reduce uncertainty when assessing risk. Because the dermal route is so important to characterizing occupational risk, methods to improve the accuracy of dermal absorption estimates are suggested, including the use of human subjects to study dermal absorption. Additional suggestions include tailoring dermal, oral and inhalation kinetic study designs to reflect worker exposure dosages. Suggestions are made to routinely conduct a single dose toxicity study patterned after the neurotoxicity study design to distinguish single dose effects and NOAELs from those resulting from multiple doses. Finally, interspecies pharmacokinetics studies are proposed to determine which toxicology study regimen of dosing best reflects intermittent worker exposure. 

Occupational Exposure to Pesticides and Risk of Non-Hodgkin's Lymphoma

American Journal of Epidemiology, 2005

Pesticide exposure may be a risk factor for non-Hodgkin's lymphoma, but it is not certain which types of pesticides are involved. A population-based case-control study was undertaken in 2000-2001 using detailed methods of assessing occupational pesticide exposure. Cases with incident non-Hodgkin's lymphoma in two Australian states (n = 694) and controls (n = 694) were chosen from Australian electoral rolls. Logistic regression was used to estimate the risks of non-Hodgkin's lymphoma associated with exposure to subgroups of pesticides after adjustment for age, sex, ethnic origin, and residence. Approximately 10% of cases and controls had incurred pesticide exposure. Substantial exposure to any pesticide was associated with a trebling of the risk of non-Hodgkin's lymphoma (odds ratio = 3.09, 95% confidence interval: 1.42, 6.70). Subjects with substantial exposure to organochlorines, organophosphates, and "other pesticides" (all other pesticides excluding herbicides) and herbicides other than phenoxy herbicides had similarly increased risks, although the increase was statistically significant only for "other pesticides." None of the exposure metrics (probability, level, frequency, duration, or years of exposure) were associated with non-Hodgkin's lymphoma. Analyses of the major World Health Organization subtypes of non-Hodgkin's lymphoma suggested a stronger effect for follicular lymphoma. These increases in risk of non-Hodgkin's lymphoma with substantial occupational pesticide exposure are consistent with previous work.

Exposure to pesticides and development of hematological cancers: a case-control study

Research, Society and Development

The aim of this study was to analyze the association between chronic exposure to pesticides and the development of hematological cancers in a region with intense agricultural activity. This is a hospital-based case-control study. Socioeconomic, demographic, occupational and health-related aspects of patients were investigated. The univariate odds ratio (OR) of cases was verified using logistic regression analysis. In the multivariate analysis, the relevant variables in the model were maintained (p = 0.05). There was a predominance of males in the case (54.0%) and control (53.0%) groups. The mean age was 58.8 ± 14.5 years in the case group and 55.6 ± 12.9 years in the control group. It was found that 38.7% of the cases were farmers, and that contact for more than five years with pesticides increases the chances of developing hematological cancers by 2.19 times (OR = 2.19; 95% CI 1, 19 - 4.06). It was also found that the higher the family income, the lower the chances of these neoplas...