Influence of geographic location in modeling blood pesticide levels in a community surrounding a U.S. Environmental protection agency superfund site

Neurotoxicity of pesticides

Pesticides are unique environmental contaminants that are specifically introduced into the environment to control pests, often by killing them. Although pesticide application serves many important purposes, including protection against crop loss and against vector-borne diseases, there are significant concerns over the potential toxic effects of pesticides to non-target organisms, including humans. In many cases, the molecular target of a pesticide is shared by non-target species, leading to the potential for untoward effects. Here, we review the history of pesticide usage and the neurotoxicity of selected classes of pesticides, including insecticides, herbicides, and fungicides, to humans and experimental animals. Specific emphasis is given to linkages between exposure to pesticides and risk of neurological disease and dysfunction in humans coupled with mechanistic findings in humans and animal models. Finally, we discuss emerging techniques and strategies to improve translation from animal models to humans.

Developing a geostatistical simulation method to inform the quantity and placement of new monitors for a follow-up air sampling campaign

Sampling campaign design is a crucial aspect of air pollution exposure studies. Selection of both monitor numbers and locations is important for maximizing measured information, while minimizing bias and costs. We developed a two-stage geostatistical-based method using pilot NO₂ samples from Lanzhou, China with the goal of improving sample design decision-making, including monitor numbers and spatial pattern. In the first step, we evaluate how additional monitors change prediction precision through minimized kriging variance. This was assessed in a Monte Carlo fashion by adding up to 50 new monitors to our existing sites with assigned concentrations based on conditionally simulated NO₂ surfaces. After identifying a number of additional sample sites, a second step evaluates their potential placement using a similar Monte Carlo scheme. Evaluations are based on prediction precision and accuracy. Costs are also considered in the analysis. It was determined that adding 28-locations to the existing Lanzhou NO₂ sampling campaign captured 73.5% of the total kriged variance improvement and resulted in predictions that were on average within 10.9 μg/m³ of measured values, while using 56% of the potential budget. Additional monitor sites improved kriging variance in a nonlinear fashion. This method development allows for informed sampling design by quantifying prediction improvement (accuracy and precision) against the costs of monitor deployment.

Toxicological profile of organochlorines aldrin and dieldrin: an Indian perspective

Several epidemiological studies have suggested various environmental factors as a possible cause for increased incidence of various abnormalities. Of the various environmental contaminants, the most prevalent and the most discussed are the endocrine disrupting chemicals. Contact of such disruptors with humans has become inevitable today. They are cosmopolitan and present from agriculture to industrial sectors, even in day-to-day consumer products. Aldrin and dieldrin belong to one such class of substances which are known to have a toxic effect on various physiological systems of the human body. Despite an imposed ban on their manufacture and commercial use, these pesticides could still be detected in probable areas of consumption like agriculture. The present review discusses the known possible toxic effects of aldrin and dieldrin and their current existence in the ecosystem across India.

Validity of geographically modeled environmental exposure estimates

Geographic modeling is increasingly being used to estimate long-term environmental exposures in epidemiologic studies of chronic disease outcomes. However, without validation against measured environmental concentrations, personal exposure levels, or biologic doses, these models cannot be assumed a priori to be accurate. This article discusses three examples of epidemiologic associations involving exposures estimated using geographic modeling, and identifies important issues that affect geographically modeled exposure assessment in these areas. In air pollution epidemiology, geographic models of fine particulate matter levels have frequently been validated against measured environmental levels, but comparisons between ambient and personal exposure levels have shown only moderate correlations. Estimating exposure to magnetic fields by using geographically modeled distances is problematic because the error is larger at short distances, where field levels can vary substantially. Geographic models of environmental exposure to pesticides, including paraquat, have seldom been validated against environmental or personal levels, and validation studies have yielded inconsistent and typically modest results. In general, the exposure misclassification resulting from geographic models of environmental exposures can be differential and can result in bias away from the null even if non-differential. Therefore, geographic exposure models must be rigorously constructed and validated if they are to be relied upon to produce credible scientific results to inform epidemiologic research. To our knowledge, such models have not yet successfully predicted an association between an environmental exposure and a chronic disease outcome that has eventually been established as causal, and may not be capable of doing so in the absence of thorough validation.

Elevated serum pesticide levels and risk for Alzheimer disease

IMPORTANCE

The causes of late-onset Alzheimer disease (AD) are not yet understood but likely include a combination of genetic, environmental, and lifestyle factors. Limited epidemiological studies suggest that occupational pesticide exposures are associated with AD. Previously, we reported that serum levels of dichlorodiphenyldichloroethylene (DDE), the metabolite of the pesticide dichlorodiphenyltrichloroethane (DDT), were elevated in a small number of patients with AD (n=20).

OBJECTIVE

To evaluate the association between serum levels of DDE and AD and whether the apolipoprotein E (APOE) genotype modifies the association.

DESIGN, SETTING, AND PARTICIPANTS

A case-control study consisting of existing samples from patients with AD and control participants from the Emory University Alzheimer's Disease Research Center and the University of Texas Southwestern Medical School's Alzheimer's Disease Center. Serum levels of DDE were measured in 79 control and 86 AD cases.

MAIN OUTCOMES AND MEASURES

Serum DDE levels, AD diagnosis, severity of AD measured by the Mini-Mental State Examination score, and interaction with APOE4 status.

RESULTS

Levels of DDE were 3.8-fold higher in the serum of those with AD (mean [SEM], 2.64 [0.35] ng/mg cholesterol) when compared with control participants (mean [SEM], 0.69 [0.1] ng/mg cholesterol; P < .001). The highest tertile of DDE levels was associated with an odds ratio of 4.18 for increased risk for AD (95% CI, 2.54-5.82; P < .001) and lower Mini-Mental State Examination scores (-1.605; range, -3.095 to -0.114; P < .0001). The Mini-Mental State Examination scores in the highest tertile of DDE were -1.753 points lower in the subpopulation carrying an APOE ε4 allele compared with those carrying an APOE ε3 allele (P interaction = .04). Serum levels of DDE were highly correlated with brain levels of DDE (ρ = 0.95). Exposure of human neuroblastoma cells to DDT or DDE increased levels of amyloid precursor protein.

CONCLUSIONS AND RELEVANCE

Elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele may be more susceptible to the effects of DDE. Both DDT and DDE increase amyloid precursor protein levels, providing mechanistic plausibility for the association of DDE exposure with AD. Identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of AD.

Multivariate models to predict human adipose tissue PCB concentrations in Southern Spain

The use of Polychlorinated biphenyls (PCBs) has been severely restricted due to their high toxicity and persistency in the environment. However, the presence of PCBs in human tissues nowadays is still been reported worldwide. Background exposure predictors of the human PCB body burden require more precise understanding. In the present study, PCB congeners 138, 153, and 180 were quantified in adult adipose tissue samples (n=387) from Granada Province (Southern Spain) and data on potential predictors of PCB concentrations were gathered by questionnaire. Chemical analysis of the selected congeners was done by gas chromatography and mass spectrometry, and multivariate analyses were performed stratifying by gender. PCB residues were quantified in 92% (PCB 153), 90% (PCB 180), and 86% (PCB 138) of the population. Geometric mean concentrations were 161.65+/-4.41 ng/g lipid for PCB 153, 111.62+/-6.27 ng/g lipid for PCB 180, and 38.41+/-8.61 ng/g lipid for PCB 138. Multivariate models explained 30-36% of the variability in PCB concentrations. Age and body mass index (BMI) predicted exposure in both males and females and were positively correlated with the concentration of the three PCB congeners. Occupation and diet predicted exposure in the males, whereas only dietary predictors were observed in the females. Further in-depth studies are required to investigate the influence of dietary habits on the bioaccumulation of PCBs and to evaluate the impact of policies aimed at reducing human exposure.

Increased hospitalizations for ischemic stroke with comorbid diabetes and residential proximity to sources of organic pollutants: a 12-year population-based study

BACKGROUND

Evidence is emerging that exposure to persistent organic pollutants (POP) is a risk factor for atherosclerosis-related diseases and for diabetes mellitus (DM). We hypothesized that residential proximity to sources of POP will be associated with an increase in hospitalization rates for ischemic stroke (IS) with comorbid DM (IS-DM).

METHODS

We examined IS-DM hospitalization rates in the New York State (exclusive of New York City) during a 12-year period. POP exposure status was assessed based on residency in a zip code containing or abutting environmental sources of POP. Adjusted relative risks (RR) of IS-DM hospitalization were estimated by multivariate Poisson regression.

RESULTS

A statistically significant 10% increase in IS-DM hospitalization rates was observed in populations environmentally exposed to POP (adjusted RR 1.10, 95% confidence interval, CI, 1.01-1.20; p = 0.031). IS-DM hospitalization rates were also higher in males (adjusted RR 1.34, 95% CI 1.30-1.39; p < 0.001), in blacks (adjusted RR 4.54, 95% CI 4.16-4.94; p < 0.001) and in older age groups (p for trend <0.001).

CONCLUSIONS

Residential proximity to sources of POP is associated with an increase in RR of IS-DM hospitalization. Our findings support the hypothesis of POP being a risk factor for IS. Further studies are warranted.

Persistent organochlorine pesticides in serum and risk of Parkinson disease

BACKGROUND

Pesticides have been implicated as likely environmental risk factors for Parkinson disease (PD), but assessment of past exposure to pesticides can be difficult. No prior studies of pesticide exposure and PD used biomarkers of exposure collected before the onset of PD. Our investigation examined the association between prospective serum biomarkers of organochlorine pesticides and PD.

METHODS

We conducted a nested case-control study within the Finnish Mobile Clinic Health Examination Survey, with serum samples collected during 1968-1972, and analyzed in 2005-2007 for organochlorine pesticides. Incident PD cases were identified through the Social Insurance Institution's nationwide registry and were confirmed by review of medical records (n = 101). Controls (n = 349) were matched for age, sex, municipality, and vital status. Adjusted odds ratios (ORs) of PD were estimated using logistic regression.

RESULTS

Little association emerged with a summary score of the 5 organochlorine pesticides found at high levels, and only increasing dieldrin concentrations trended toward a higher risk of PD (OR per interquartile range [IQR] 1.28, 95% confidence interval [CI] 0.97-1.69, p = 0.08). Because of possible strong confounding by cigarette smoking among smokers, we ran additional analyses restricted to never smokers (n = 68 cases, 183 controls). In these analyses, increasing dieldrin concentrations were associated with increased odds of PD (OR per IQR 1.95, 95% CI 1.26-3.02, p = 0.003). None of the other organochlorine pesticides were associated with PD in these analyses.

CONCLUSIONS

These results provide some support for an increased risk of Parkinson disease with exposure to dieldrin, but chance or exposure correlation with other less persistent pesticides could contribute to our findings.

Using imputation to provide location information for nongeocoded addresses

Background

The importance of geography as a source of variation in health research continues to receive sustained attention in the literature. The inclusion of geographic information in such research often begins by adding data to a map which is predicated by some knowledge of location. A precise level of spatial information is conventionally achieved through geocoding, the geographic information system (GIS) process of translating mailing address information to coordinates on a map. The geocoding process is not without its limitations, though, since there is always a percentage of addresses which cannot be converted successfully (nongeocodable). This raises concerns regarding bias since traditionally the practice has been to exclude nongeocoded data records from analysis.

Methodology/Principal Findings

In this manuscript we develop and evaluate a set of imputation strategies for dealing with missing spatial information from nongeocoded addresses. The strategies are developed assuming a known zip code with increasing use of collateral information, namely the spatial distribution of the population at risk. Strategies are evaluated using prostate cancer data obtained from the Maryland Cancer Registry. We consider total case enumerations at the Census county, tract, and block group level as the outcome of interest when applying and evaluating the methods. Multiple imputation is used to provide estimated total case counts based on complete data (geocodes plus imputed nongeocodes) with a measure of uncertainty. Results indicate that the imputation strategy based on using available population-based age, gender, and race information performed the best overall at the county, tract, and block group levels.

Conclusions/Significance

The procedure allows for the potentially biased and likely under reported outcome, case enumerations based on only the geocoded records, to be presented with a statistically adjusted count (imputed count) with a measure of uncertainty that are based on all the case data, the geocodes and imputed nongeocodes. Similar strategies can be applied in other analysis settings.

Assessment of community food resources: A Latino neighborhood study in upstate New York

This study aims to assess availability, affordability, and accessibility of food items in a low-income Latino neighborhood within a small city using an on-site food store survey. Store locations were identified by on-site GPS. Results showed the Latino neighborhood had limited availability and above average cost of high-fiber bread. Fresh vegetables were more expensive compared to the non-Latino neighborhood, and more stores in the Latino neighborhood participated in Supplemental Nutrition Assistance Food Program. The lack of supermarkets, fewer stores with disability access, and the lack of public transportation left Latino residents without a vehicle or with physical disabilities with few food shopping options.

Spatial modeling of personalized exposure dynamics: the case of pesticide use in small-scale agricultural production landscapes of the developing world

Background

Pesticide poisoning is a global health issue with the largest impacts in the developing countries where residential and small-scale agricultural areas are often integrated and pesticides sprayed manually. To reduce health risks from pesticide exposure approaches for personalized exposure assessment (PEA) are needed. We present a conceptual framework to develop a spatial individual-based model (IBM) prototype for assessing potential exposure of farm-workers conducting small-scale agricultural production, which accounts for a considerable portion of global food crop production. Our approach accounts for dynamics in the contaminant distributions in the environment, as well as patterns of movement and activities performed on an individual level under different safety scenarios. We demonstrate a first prototype using data from a study area in a rural part of Colombia, South America.

Results

Different safety scenarios of PEA were run by including weighting schemes for activities performed under different safety conditions. We examined the sensitivity of individual exposure estimates to varying patterns of pesticide application and varying individual patterns of movement. This resulted in a considerable variation in estimates of magnitude, frequency and duration of exposure over the model runs for each individual as well as between individuals. These findings indicate the influence of patterns of pesticide application, individual spatial patterns of movement as well as safety conditions on personalized exposure in the agricultural production landscape that is the focus of our research.

Conclusion

This approach represents a conceptual framework for developing individual based models to carry out PEA in small-scale agricultural settings in the developing world based on individual patterns of movement, safety conditions, and dynamic contaminant distributions.

The results of our analysis indicate our prototype model is sufficiently sensitive to differentiate and quantify the influence of individual patterns of movement and decision-based pesticide management activities on potential exposure. This approach represents a framework for further understanding the contribution of agricultural pesticide use to exposure in the small-scale agricultural production landscape of many developing countries, and could be useful to evaluate public health intervention strategies to reduce risks to farm-workers and their families. Further research is needed to fully develop an operational version of the model.

Differences in serum concentrations of organochlorine compounds by occupational social class in pancreatic cancer

BACKGROUND

The relationships between social factors and body concentrations of environmental chemical agents are unknown in many human populations. Some chemical compounds may play an etiopathogenic role in pancreatic cancer.

OBJECTIVE

To analyze the relationships between occupational social class and serum concentrations of seven selected organochlorine compounds (OCs) in exocrine pancreatic cancer: dichlorodiphenyltrichloroethane (p,p'-DDT), dichlorodiphenyldichloroethene (p,p'-DDE), 3 polychlorinated biphenyls (PCBs), hexachlorobenzene, and beta-hexachlorocyclohexane.

METHODS

Incident cases of exocrine pancreatic cancer were prospectively identified, and interviewed face-to-face during hospital admission (n=135). Serum concentrations of OCs were analyzed by high-resolution gas chromatography with electron-capture detection. Social class was classified according to occupation.

RESULTS

Multivariate-adjusted concentrations of all seven compounds were higher in occupational social classes IV-V (the less affluent) than in classes I-II; they were higher as well in class III than in classes I-II for four compounds. Concentrations of six OCs were higher in manual workers than in non-manual workers (p<0.05 for PCBs). Social class explained statistically between 3.7% and 5.7% of the variability in concentrations of PCBs, and 2% or less variability in the other OCs.

CONCLUSIONS

Concentrations of most OCs were higher in the less affluent occupational social classes. In pancreatic cancer the putative causal role of these persistent organic pollutants may not be independent of social class. There is a need to integrate evidence on the contribution of different social processes and environmental chemical exposures to the etiology of pancreatic and other cancers.

Population-based research on occupational and environmental factors for leukemia and non-Hodgkin's lymphoma: the Northern Germany Leukemia and Lymphoma Study (NLL)

BACKGROUND

The Northern Germany Leukemia and Lymphoma Study (NLL) is a population-based study designed to provide a quantitative basis for investigations into occupational and environmental risk factors for leukemia and lymphoma.

METHODS

All incident cases of leukemia and lymphoma diagnosed between 1/1/1986 and 12/31/1998 in six counties in Northern Germany were actively ascertained. Controls were selected from population registries. Use of pesticides, sources of food supply, time spent at home and work, medical and family history were assessed via face-to-face interview. This self-reported information was used in conjunction with direct environmental measurements of pesticides in household dust and electromagnetic fields (EMFs). In addition, geographical information system (GIS) data were used to derive estimates of environmental exposure to pesticides, EMFs associated with transmission lines, and ionizing radiation from routine nuclear power reactor operations. Occupational exposure assessment was based on lifetime work history. For each job, information on branch of industry, company, job description, and duration of employment were ascertained.

RESULTS

Fourteen hundred thirty cases and 3041 controls were recruited. Lifetime residential and workplace histories totaled 49,628 addresses. Occupational exposure to pesticides was reported by 15% of the male participants (women: 16%). Four percent of the men (women: 8%) were occupationally exposed to ionizing radiation for >or=1 year over their lifetime. Sixty four percent of the participants had lived in the vicinity (20 km) of a nuclear power plant in operation.

CONCLUSIONS

The NLL illustrates the successful application of innovative methods to simultaneously assess occupational and environmental risk factors for leukemia and lymphoma including radiological hazards, pesticides, and EMFs.

Fetal deaths and proximity to hazardous waste sites in Washington State

BACKGROUND

The in utero period is one of increased susceptibility to environmental effects. The effects of prenatal exposure to environmental toxicants on various adverse pregnancy outcomes, including fetal death, are not well understood.

OBJECTIVE

We examined the risk of fetal death in relation to maternal residential proximity to hazardous waste sites.

METHODS

We conducted a population-based case-control study using Washington State vital records for 1987-2001. Cases were women with fetal deaths at > or = 20 weeks (n = 7,054). Ten controls per case were randomly selected from live births. Locations of 939 hazardous waste sites were identified from the Department of Ecology registry. We measured distance from maternal residence at delivery to the nearest hazardous waste site, and calculated odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The risk of fetal death for women residing < or = 0.5 miles, relative to > 5 miles, from a hazardous waste site was not increased (adjusted OR = 1.06; 95% CI, 0.90-1.25). No associations were observed for any proximity categories < or = 5 miles from sites with contaminated air, soil, water, solvents, or metals; however, fetal death risk increased among women residing < or = 1 mile from pesticide-containing sites (OR = 1.28; 95% CI, 1.13-1.46).

CONCLUSION

These results do not suggest that fetal death is associated with residential proximity to hazardous waste sites overall; however, close proximity to pesticide-containing sites may increase the risk of fetal death.

Increased rate of hospitalization for diabetes and residential proximity of hazardous waste sites

BACKGROUND

Epidemiologic studies suggest that there may be an association between environmental exposure to persistent organic pollutants (POPs) and diabetes.

OBJECTIVE

The aim of this study was to test the hypothesis that residential proximity to POP-contaminated waste sites result in increased rates of hospitalization for diabetes.

METHODS

We determined the number of hospitalized patients 25-74 years of age diagnosed with diabetes in New York State exclusive of New York City for the years 1993-2000. Descriptive statistics and negative binomial regression were used to compare diabetes hospitalization rates in individuals who resided in ZIP codes containing or abutting hazardous waste sites containing POPs ("POP" sites); ZIP codes containing hazardous waste sites but with wastes other than POPs ("other" sites); and ZIP codes without any identified hazardous waste sites ("clean" sites).

RESULTS

Compared with the hospitalization rates for diabetes in clean sites, the rate ratios for diabetes discharges for people residing in POP sites and "other" sites, after adjustment for potential confounders were 1.23 [95% confidence interval (CI), 1.15-1.32] and 1.25 (95% CI, 1.16-1.34), respectively. In a subset of POP sites along the Hudson River, where there is higher income, less smoking, better diet, and more exercise, the rate ratio was 1.36 (95% CI, 1.26-1.47) compared to clean sites.

CONCLUSIONS

After controlling for major confounders, we found a statistically significant increase in the rate of hospitalization for diabetes among the population residing in the ZIP codes containing toxic waste sites.