Assessment of pesticide exposure in the agricultural population of Costa Rica

We describe a model for the retrospective assessment of parental exposure to 26 pesticides, selected by toxicity-based prioritization, in a population-based case-control study of childhood leukaemia in Costa Rica (301 cases, 582 controls). The model was applied to a subset of 227 parents who had been employed or self-employed in agriculture or livestock breeding. It combines external data on pesticide use for 14 crops, 21 calendar years and 14 regions, and individual interview data on determinants (task and technology, personal protective equipment, field reentry, storing of pesticides, personal hygiene) of exposure. Recall was enhanced by use of checklists of pesticides in the interview. An external database provided information on the application rate (proxy for intensity of potential exposure) for each pesticide. The calendar time was individually converted to five time windows (year before conception, first, second and third trimester, and first year of the child). Time-windowed individual data on determinants of exposure and their expert-based general weights and their category-specific hazard values jointly provided an individual determinant score. This score was multiplied by the application rate to obtain an individual index of exposure intensity during application. Finally, average exposure intensity during entire time windows was estimated by incorporating in the model the individual time fraction of exposure during application. Estimates of exposure intensities were proxies assumed to be proportional to dermal exposure intensity, which represents the major pathway of occupational exposure to pesticides. A simulated sensitivity analysis resulted in a correlation coefficient of 0.91 between two sets of 10 000 values of individual exposure indices, based on two different but realistic sets expert-assigned weights. Lack of measurement data on concurrent exposures in comparable circumstances precluded direct validation of the model.     

Surveillance and epidemiology of occupational pesticide poisonings on banana plantations in Costa Rica

A review of one year's workers' compensation records from the Costa Rican National Insurance Institute was performed in a banana plantation region to determine rates of and risk factors for agrichemical poisonings. Review of 9,060 medical records revealed that the most commonly reported agrichemical-related injuries (n=800) were chemical burns (28%) and acute intoxications (21%). Other agrichemical-related injuries included eye injuries, chemical dermatoses, and chronic fungal infections. The incidences and types of injuries differed between male and female workers and workers of different age groups. Older female workers were more likely to report chemical dermatoses. Young male workers were more likely to experience acute intoxication. These differences seem to be attributable to divisions of labor by gender and age among plantation workers.     

Parental occupational exposure to pesticides and the risk of childhood leukemia in Costa Rica

OBJECTIVES: Parental exposure to pesticides and the risk of leukemia in offspring were examined in a population-based case-control study in Costa Rica. METHODS: All cases of childhood leukemia (N=334), in 1995-2000, were identified at the Cancer Registry and the Children's Hospital. Population controls (N=579) were drawn from the National Birth Registry. Interviews of parents were conducted using conventional and icon-based calendar forms. An exposure model was constructed for 25 pesticides in five time periods. RESULTS: Mothers' exposures to any pesticides during the year before conception and during the first and second trimesters were associated with the risk [odds ratio (OR) 2.4, 95% confidence interval (95% CI) 1.0-5.9; OR 22, 95% CI 2.8-171.5; OR 4.5, 95% CI 1.4-14.7, respectively] and during anytime (OR 2.2, 95% CI 1.0-4.8). An association was found for fathers' exposures to any pesticides during the second trimester (OR 1.5, 95% CI 1.0-2.3). An increased risk with respect to organophosphates was found for mothers during the first trimester (OR 3.5, 95% CI 1.0-12.2) and for fathers during the year before conception and the first trimester (OR 1.5, 95% CI 1.0-2.2 and OR 1.6, 95% CI 1.0-2.6, respectively), and benzimidazoles during the first, second, and third trimesters of pregnancy (OR 2.2, 95% CI 1.0-4.4; OR 2.2, 95% CI 1.0-5.0; OR 2.2, 95% CI 1.0-5.2, respectively). There was a suggestion of an exposure-response gradient for fathers as regards picloram, benomyl, and paraquat. Age at diagnosis was positively associated with fathers' exposures and inversely associated with mothers' exposures. CONCLUSIONS: The results suggest that parental exposure to certain pesticides may increase the risk of leukemia in offspring.     

Workplace carcinogen and pesticide exposures in Costa Rica

The CAREX data system converts national workforce volumes and proportions of workers exposed to workplace carcinogens into numbers of exposed in 55 industrial categories. CAREX was adapted for Costa Rica for 27 carcinogens and seven groups of pesticides. Widespread workplace carcinogens in the 1.3 million workforce of Costa Rica are solar radiation (333,000 workers), diesel engine exhaust (278,000), environmental tobacco smoke (71,000), hexavalent chromium compounds (55,000), benzene (52,000), wood dust (32,000), silica dust (27,000), lead and inorganic lead compounds (19,000), and polycyclic aromatic compounds (17,000). The most ubiquitous pesticides were paraquat and diquat (175,000), mancozeb, maneb, and zineb (49,000), chlorothalonil (38,000), benomyl (19,000), and chlorophenoxy herbicides (11,000). Among women, formaldehyde, radon, and methylene chloride overrode pesticides, chromium, wood dust, and silica dust in numbers of exposed. High-risk sectors included agriculture, construction, personal and household services, land and water transport and allied services, pottery and similar industries, woodworks, mining, forestry and logging, fishing, manufacturing of electrical machinery, and bar and restaurant personnel.     

Sterilization of workers from pesticide exposure: the causes and consequences of DBCP-induced damage in Costa Rica and beyond.

Public health hazards from the use of agricultural pesticides have received increasing attention in developing as well as industrial nations. This article examines a remarkable case of massive sterilization of approximately 1,500 workers in Costa Rica, due to exposure to a toxic nematicide called DBCP 1,2-dibromo-3-chloropropane), applied in large commercial banana plantations. Although the product was used during the 1970s, sterile victims have continued to be diagnosed through the 1980s. The effects include psychological trauma as well as permanent infertility. The case has international repercussions because several hundred workers have filed law suits against the U.S.-based transnational DBCP manufacturers, and because DBCP use was continued during the 1980s in other developing nations. The author analyzes the causes behind this serious impairment. It is argued that the contributing factors include not only biomedical processes and technical dimensions (i.e., how DBCP was used), but most importantly, political-economic factors that explain how and why DBCP was used despite the severe hazard. The crucial determinants pertain to the dominance of short-term profit motives, and the control over information and technology by the manufacturers (who concealed early toxicological research evidence of the reproductive hazards) and by the managers of the banana producer-companies. This case well illustrates problems and injustices from labor exploitation and resource extraction from transnational agro-industries. The article concludes with a brief summary of policy implications from the case.     

Geographical differences in cancer incidence in the Amazon basin of Ecuador in relation to residence near oil fields

BACKGROUND: Since 1972, oil companies have extracted more than 2 billion barrels of crude oil from the Ecuadorian Amazon, releasing billions of gallons of untreated wastes and oil directly into the environment. This study aimed to determine if there was any difference in overall and specific cancer incidence rates between populations living in proximity to oil fields and those who live in areas free from oil exploitation. METHODS: Cancer cases from the provinces of Sucumbios, Orellana, Napo and Pastaza during the period 1985-1998 were included in the study. The exposed population was defined as those living in a county (n = 4) where oil exploitation had been ongoing for a minimum of 20 years up to the date of the study. Non-exposed counties were identified as those (n = 11) without oil development activities. Relative risks (RR) along with 95% CI were calculated for men and women as ratios of the age-adjusted incidence rates in the exposed versus non-exposed group. RESULTS: The RR of all cancer sites combined was significantly elevated in both men and women in exposed counties. Significantly elevated RR were observed for cancers of the stomach, rectum, skin melanoma, soft tissue and kidney in men and for cancers of the cervix and lymph nodes in women. An increase in haematopoietic cancers was also observed in the population under 10 years in the exposed counties in both males and females. CONCLUSION: Study results are compatible with a relationship between cancer incidence and living in proximity to oil fields. An environmental monitoring and cancer surveillance system in the area is recommended.     

Pendimethalin exposure and cancer incidence among pesticide applicators

BACKGROUND: Pendimethalin, a widely used herbicide, has been classified as a group C possible human carcinogen by the U.S. Environmental Protection Agency. We evaluated the incidence of cancer in relation to reported pendimethelin use among pesticide applicators in the Agricultural Health Study, a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. METHODS: Information on pesticide use came from two questionnaires (enrollment and take-home). The present analysis includes 9089 pendimethalin-exposed and 15,285 nonpendimethalin-exposed pesticide applicators with complete information on pendimethalin use and covariates from a take-home questionnaire. We conducted Poisson regression analyses to evaluate the association of pendimethalin exposure with cancer incidence (mean follow-up = 7.5 years) using two exposure metrics: tertiles of lifetime days of exposure and tertiles of intensity-weighted lifetime days of exposure. RESULTS: Overall cancer incidence did not increase with increasing lifetime pendimethalin use, and there was no clear evidence of an association between pendimethalin use and risks for specific cancers. The risk for rectal cancer rose with increasing lifetime pendimethalin exposure when using nonexposed as the reference (rate ratio = 4.3; 95% confidence interval = 1.5-12.7 for the highest exposed subjects; P for trend = 0.007), but the association was attenuated when using the low exposed as the referent group (P for trend = 0.08). Similar patterns for rectal cancer were observed when using intensity-weighted exposure-days. The number of rectal cancer cases among the pendimethalin-exposed was small (n = 19). There was some evidence for an elevated risk for lung cancer, but the excess occurred only in the highest exposure category for lifetime pendimethalin exposure. The trends for lung cancer risk were inconsistent for different exposure metrics. CONCLUSIONS: We did not find a clear association of lifetime pendimethalin exposure either with overall cancer incidence or with specific cancer sites.     

Histologic differences in occupational risks of lung cancer incidence

A five-year total community study of lung cancer incidence by occupation revealed that 1) virtually all the cases occurred in smokers; 2) all major histologic types of lung cancer were strongly associated with smoking behavior; 3) in most high-risk occupations the significant elevations of risk were limited to one or two histologic types, a specificity suggestive of the importance of workplace carcinogen exposure; and 4) both sensitivity and specificity of the search for occupations with lung cancer hazards were greatly increased by use of histologic type rates rather than total lung cancer rates. The epidemiologic differences among histologic types suggest that the lung cancers might be a group of neoplastic diseases which share a major risk factor (smoking) in common but which differ in respect to exposure to other carcinogens. Eventual control of our lung cancer epidemic will require the allocation of much greater resources to documentation of the occupational risks.     

Longitudinal relation of community-level income inequality and mortality in Costa Rica

The controversy regarding the direct relationship between income distribution and health remains unresolved. Empirical evidence has often failed to advance our understanding because in the countries studied there was limited ability to distinguish hypotheses. This study examines the relation between inequality and mortality in the context of Costa Rica. Costa Rica's unique social and political structure makes confounding through resource and political channels less likely, thus any effects would work predominantly through direct psychosocial channels. Using mortality data extracted from the Vital Statistics Registry, we evaluate the longitudinal relations between lagged and contemporaneous income inequality and cause-specific mortality in Costa Rica from 1995 to 2005. For those aged 15–60, results indicate that there is a significant adverse relation between increases in lagged inequality and mortality from liver disease, and marginal adverse relations with mortality from diabetes and suicide. For those aged 60 and over, there is a limited evidence of a relation between inequality and health. These results suggest increases in inequality may impact health behavior of the working aged population in Costa Rica.     

Estimating the incidence of lung cancer attributable to occupational exposure in Iran

Objective  

The aim of this study was to estimate the fraction of lung cancer incidence in Iran attributed to occupational exposures to the well-established lung cancer carcinogens, including silica, cadmium, nickel, arsenic, chromium, diesel fumes, beryllium, and asbestos.     

Registration of fatal occupational injuries in Costa Rica, 2005-2006

Data on fatal occupational injuries (FOIs) for Latin America are controversial. Costa Rican national rates are inconsistent with estimates extrapolated from other countries. We reviewed the files for all possible FOIs in Costa Rica for 2005-2006 at the National Insurance Institute and at the Center of Forensic Sciences by formality/informality of work, sex, age, economic activity, occupation, and cause of death. The national mortality rate was estimated at 9.5/100,000 person-years (342 deaths). The informal/formal rate ratio was 1.06. Men's rates were over 10 times higher than women's and increased with age. The highest rates were found for transport, storage, and communication (32.1/100,000 person-years), and, by occupation, for messengers and delivery men (91.4). Leading causes of death were traffic injuries and gunshots. Recalculated rates are probably underestimates. Data limitations include the absence of systematic identification and registration among informal sector workers and other groups such as children and farm workers.     

Bladder cancer and occupational exposure to leather.

A large case-control study of bladder cancer (2982 cases; 5782 controls) included information about occupational exposure to leather. Occupational histories of exposed white study subjects were reviewed and 150 were determined to have had "true" on the job exposure to leather. The odds ratio estimate (OR) of bladder cancer associated with such exposure in white subjects (n = 8063) was 1.4 (95% confidence limits = 1.0, 1.9) after adjustment for sex, age, and cigarette smoking. The risk was highest in those first employed in a leather job before 1945, although no dose-response relation with duration of leather employment was found. Subjects employed in "dusty" leather jobs had a slightly higher risk than those with other types of leather jobs. Our results are consistent with reports of an increased risk of bladder cancer associated with exposure to leather. Although the agents responsible have not been identified, our findings of an increased risk associated with exposure in the earlier years of this century and in dusty jobs suggest that leather dusts may be important.     

Dust exposure in workers from grain storage facilities in Costa Rica

Background

About 12 million workers are involved in the production of basic grains in Central America. However, few studies in the region have examined the occupational factors associated with inhalable dust exposure.

Meta-analysis of studies of occupational exposure to vinyl chloride in relation to cancer mortality

OBJECTIVE: A meta-analysis was made of studies addressing occupational exposure to vinyl chloride in relation to cancer mortality. METHODS: Two recently updated multicenter cohort studies and six smaller studies were identified. For selected neoplasms, standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were abstracted (or calculated from raw data). In cases of lack of heterogeneity (P-value > or = 0.01), meta-analyses were conducted using a random-effects model. RESULTS: With SMR values ranging from 1.63 to 57.1, all six studies for which these ratios could be obtained suggested an increased risk of liver cancer. For four of these studies, excesses persisted when known cases of angiosarcoma of the liver (ASL) were excluded. The meta-SMR for liver cancers other than ASL (based on the 2 large cohorts) was 1.35 (95% CI 1.04-1.77). The meta-SMR for lung cancer was 0.90 (95% CI 0.77-1.00, based on 5 studies), although higher SMR values were reported in early studies. The meta-SMR for brain cancer, based on 5 studies, was 1.26 (95% CI 0.98-1.62). For soft tissue sarcomas, the meta-SMR based on 4 studies was 2.52 (95% CI 1.56-4.07). The meta-SMR for lymphatic and hematopoietic neoplasms in the 2 large studies was 0.90 (95% CI 0.75-1.01), although 3 of the smaller studies reported significant excesses. CONCLUSIONS: Apart from the known risk of ASL, workers exposed to vinyl chloride may experience an increased risk of hepatocellular carcinoma and soft-tissue sarcoma; however, these results may have been influenced by the underdiagnosis of true ASL. Increased mortality from lung and brain cancers and from lymphatic and hematopoietic neoplasms cannot be excluded; mortality from other neoplasms does not appear to be increased.     

Semen quality in relation to biomarkers of pesticide exposure

We previously reported reduced sperm concentration and motility in fertile men in a U.S. agrarian area (Columbia, MO) relative to men from U.S. urban centers (Minneapolis, MN; Los Angeles, CA; New York, NY). In the present study we address the hypothesis that pesticides currently used in agriculture in the Midwest contributed to these differences in semen quality. We selected men in whom all semen parameters (concentration, percentage sperm with normal morphology, and percentage motile sperm) were low (cases) and men in whom all semen parameters were within normal limits (controls) within Missouri and Minnesota (sample sizes of 50 and 36, respectively) and measured metabolites of eight current-use pesticides in urine samples provided at the time of semen collection. All pesticide analyses were conducted blind with respect to center and case-control status. Pesticide metabolite levels were elevated in Missouri cases, compared with controls, for the herbicides alachlor and atrazine and for the insecticide diazinon [2-isopropoxy-4-methyl-pyrimidinol (IMPY)]; for Wilcoxon rank test, p = 0.0007, 0.012, and 0.0004 for alachlor, atrazine, and IMPY, respectively. Men from Missouri with high levels of alachlor or IMPY were significantly more likely to be cases than were men with low levels [odds ratios (ORs) = 30.0 and 16.7 for alachlor and IMPY, respectively], as were men with atrazine levels higher than the limit of detection (OR = 11.3). The herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) and metolachlor were also associated with poor semen quality in some analyses, whereas acetochlor levels were lower in cases than in controls (p = 0.04). No significant associations were seen for any pesticides within Minnesota, where levels of agricultural pesticides were low, or for the insect repellent DEET (N,N-diethyl-m-toluamide) or the malathion metabolite malathion dicarboxylic acid. These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduction in semen quality in fertile men from mid-Missouri we reported previously.     

Assessing occupational and environmental exposure

Exposure assessment is a poorly understood component of the science of epidemiology. The relationship between exposure to chemicals and ill-health outcomes is often calculated using crude exposure measures such as ever/never exposed or duration. When investigating subtle effects, exposures need to be characterized much more fully in terms of intensity, frequency, duration and route. While occupational exposures tend to be much greater than those experienced from the wider environment there is a need to remember that, for many chemicals, exposure can occur occupationally, environmentally and through consumer use of products containing the material of interest. Inhalation exposure has generally been the traditional focus for most epidemiological investigations but there is now growing awareness of the importance of the dermal and ingested routes of contact and internalization. Quantification of the exposure also needs to be related to a biological mechanism of action and exposure metrics need to be selected accordingly. Occupational exposures can generally be measured using simple well-validated techniques. Environmental exposures require much more sensitive instruments and are more difficult to assess. Exposure modelling, particularly for the environmental fate of chemicals has undergone many recent developments and Monte Carlo techniques can be used to characterize model uncertainty and variability. This approach to exposure assessment can now be used in the setting of the wider environment and will enable a far better understanding of the relationship between exposure and disease.     

Time trends of occupational pesticide-related injuries in Costa Rica, 1982-1992

To evaluate time trends of occupational pesticide-related injuries in Costa Rica, a survey was carried out three times over a ten-year period at a national reporting system for occupational accidents and diseases among wage-earning workers. The sample comprised the accidents reported during the months of June of the years 1982, 1987, and 1992. The overall incidence rates were 1.8, 2.7, and 2.5 per 1,000 agricultural workers, respectively. Rates among female workers increased (3.1, 3.7, 5.4) and were elevated as compared with male workers (1.7, 2.6, 2.3). The trend for topical lesions was upgoing (1.2, 1.4, 2.1), consistent with an increased use of fungicides and lack of safety measures for pesticides with low acute toxicity. Systemic poisonings peaked in 1987 (0.6, 1.2, 0.5), declining in 1992 with increased use of biologic pest control and pyrethroid insecticides less toxic than cholinesterase inhibitors, and improved safety during nematocide applications on banana plantations. In 1992, despite the largest decline of systemic poisonings in the banana-producing Atlantic Region, poisonings as well as topical injuries were still four times more frequent in this region than in the rest of the country. Restriction of highly toxic pesticides together with implementation of occupational safety measures can reduce systemic poisonings in developing countries. Such policies need to be extended to other pesticides to prevent less life threatening but often disabling skin and eye injuries.