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Rauh et al., 2011

Rauh, Virginia, Arunajadai, Srikesh, Horton, Megan, Perera, Frederica, Hoepner, Lori, Barr, Dana B, & Whyatt, Robin; “Seven-year neurodevelopmental scores and prenatal exposure to chlorpyrifos, a common agricultural pesticide;” Environmental Health Perspectives, 2011, 119(8), 1196-1201; DOI: 10.1289/ehp.1003160.

ABSTRACT:

BACKGROUND: In a longitudinal birth cohort study of inner-city mothers and children (Columbia Center for Children’s Environmental Health), we have previously reported that prenatal exposure to chlorpyrifos (CPF) was associated with neurodevelopmental problems at 3 years of age.

OBJECTIVE: The goal of the study was to estimate the relationship between prenatal CPF exposure and neurodevelopment among cohort children at 7 years of age.

METHODS: In a sample of 265 children, participants in a prospective study of air pollution, we measured prenatal CPF exposure using umbilical cord blood plasma (picograms/gram plasma) and 7-year neurodevelopment using the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV). Linear regression models were used to estimate associations, with covariate selection based on two alternate approaches.

RESULTS: On average, for each standard deviation increase in CPF exposure (4.61 pg/g), Full-Scale intelligence quotient (IQ) declined by 1.4% and Working Memory declined by 2.8%. Final covariates included maternal educational level, maternal IQ, and quality of the home environment. We found no significant interactions between CPF and any covariates, including the other chemical exposures measured during the prenatal period (environmental tobacco smoke and polycyclic aromatic hydrocarbons).

CONCLUSIONS: We report evidence of deficits in Working Memory Index and Full-Scale IQ as a function of prenatal CPF exposure at 7 years of age. These findings are important in light of continued widespread use of CPF in agricultural settings and possible longer-term educational implications of early cognitive deficits.

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Nishioka et al., 2001

Nishioka, M. G., Lewis, R. G., Brinkman, M. C., Burkholder, H. M., Hines, C. E., & Menkedick, J. R.; “Distribution of 2,4-D in air and on surfaces inside residences after lawn applications: comparing exposure estimates from various media for young children;” Environmental Health Perspectives, 2001, 109(11), 1185-1191; DOI: 10.1289/ehp.011091185.

ABSTRACT:

We collected indoor air, surface wipes (floors, table tops, and window sills), and floor dust samples at multiple locations within 11 occupied and two unoccupied homes both before and after lawn application of the herbicide 2,4-D. We measured residues 1 week before and after application. We used collected samples to determine transport routes of 2,4-D from the lawn into the homes, its subsequent distribution between the indoor surfaces, and air concentration as a function of airborne particle size. We used residue measurements to estimate potential exposures within these homes. After lawn application, 2,4-D was detected in indoor air and on all surfaces throughout all homes. Track-in by an active dog and by the homeowner applicator were the most significant factors for intrusion. Resuspension of floor dust was the major source of 2,4-D in indoor air, with highest levels of 2,4-D found in the particle size range of 2.5-10 microm. Resuspended floor dust was also a major source of 2,4-D on tables and window sills. Estimated post application indoor exposure levels for young children from nondietary ingestion may be 1-10 microg/day from contact with floors, and 0.2-30 microg/day from contact with table tops. These are estimated to be about 10 times higher than the preapplication exposures. By comparison, dietary ingestion of 2,4-D is approximately 1.3 microg/day. FULL TEXT

Malagoli et al., 2016

Malagoli, C., Costanzini, S., Heck, J. E., Malavolti, M., De Girolamo, G., Oleari, P., Palazzi, G., Teggi, S., & Vinceti, M.; “Passive exposure to agricultural pesticides and risk of childhood leukemia in an Italian community;” International Journal of Hygiene and Environmental Health, 2016, 219(8), 742-748; DOI: 10.1016/j.ijheh.2016.09.015.

ABSTRACT:

BACKGROUND: Exposure to pesticides has been suggested as a risk factor for childhood leukemia, but definitive evidence on this relation and the specific pesticides involved is still not clear.

OBJECTIVE: We carried out a population-based case-control study in a Northern Italy community to assess the possible relation between passive exposure to agricultural pesticides and risk of acute childhood leukemia.

METHODS: We assessed passive pesticide exposure of 111 childhood leukemia cases and 444 matched controls by determining density and type of agricultural land use within a 100-m radius buffer around children’s homes. We focused on four common crop types, arable, orchard, vineyard and vegetable, characterized by the use of specific pesticides that are potentially involved in childhood induced leukemia. The use of these pesticides was validated within the present study. We computed the odds ratios (OR) of the disease and their 95% confidence intervals (CI) according to type and density of crops around the children’s homes, also taking into account traffic pollution and high-voltage power line magnetic field exposure.

RESULTS: Childhood leukemia risk did not increase in relation with any of the crop types with the exception of arable crops, characterized by the use of 2.4-D, MCPA, glyphosate, dicamba, triazine and cypermethrin. The very few children (n=11) residing close to arable crops had an OR for childhood leukemia of 2.04 (95% CI 0.50-8.35), and such excess risk was further enhanced among children aged <5 years.

CONCLUSIONS: Despite the null association with most crop types and the statistical imprecision of the estimates, the increased leukemia risk among children residing close to arable crops indicates the need to further investigate the involvement in disease etiology of passive exposure to herbicides and pyrethroids, though such exposure is unlikely to play a role in the vast majority of cases. FULL TEXT

Smith et al., 2017

Smith, A. M., Smith, M. T., La Merrill, M. A., Liaw, J., & Steinmaus, C.; “2,4-dichlorophenoxyacetic acid (2,4-D) and risk of non-Hodgkin lymphoma: a meta-analysis accounting for exposure levels;” Annals of Epidemiology, 2017, 27(4), 281-289 e284; DOI: 10.1016/j.annepidem.2017.03.003.

ABSTRACT:

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most commonly used selective herbicides in the world. A number of epidemiology studies have found an association between 2,4-D exposure and non-Hodgkin lymphoma (NHL) but these results are inconsistent and controversial. A previous meta-analysis found no clear association overall but did not specifically examine high-exposure groups. We conducted a systematic review and meta-analysis of the peer-reviewed epidemiologic studies of the associations between 2,4-D and NHL, with a particular focus on high-exposure groups, and evaluations of heterogeneity, dose-response, and bias. A total of 12 observational studies, 11 case-control studies, and one cohort study, were included. The summary relative risk for NHL using study results comparing subjects who were ever versus never exposed to 2,4-D was 1.38 (95% confidence interval (CI), 1.07-1.77). However, in analyses focusing on results from highly exposed groups, the summary relative risk for NHL was 1.73 (95% CI, 1.10-2.72). No clear bias based on study design, exposure assessment methodology, or outcome misclassification was seen. Overall, these findings provide new evidence for an association between NHL and exposure to the herbicide 2,4-D. FULL TEXT

Burns and Swaen, 2012

Burns, C. J., & Swaen, G. M.; “Review of 2,4-dichlorophenoxyacetic acid (2,4-D) biomonitoring and epidemiology;” Critical Reviews in Toxicology, 2012, 42(9), 768-786; DOI: 10.3109/10408444.2012.710576.

ABSTRACT:

A qualitative review of the epidemiological literature on the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and health after 2001 is presented. In order to compare the exposure of the general population, bystanders and occupational groups, their urinary levels were also reviewed. In the general population, 2,4-D exposure is at or near the level of detection (LOD). Among individuals with indirect exposure, i.e. bystanders, the urinary 2,4-D levels were also very low except in individuals with opportunity for direct contact with the herbicide. Occupational exposure, where exposure was highest, was positively correlated with behaviors related to the mixing, loading and applying process and use of personal protection. Information from biomonitoring studies increases our understanding of the validity of the exposure estimates used in epidemiology studies. The 2,4-D epidemiology literature after 2001 is broad and includes studies of cancer, reproductive toxicity, genotoxicity, and neurotoxicity. In general, a few publications have reported statistically significant associations. However, most lack precision and the results are not replicated in other independent studies. In the context of biomonitoring, the epidemiology data give no convincing or consistent evidence for any chronic adverse effect of 2,4-D in humans. FULL TEXT

Liu adn Schelar, 2012

Liu, J., & Schelar, E.; “Pesticide exposure and child neurodevelopment: summary and implications;” Workplace Health and Safety, 2012, 60(5), 235-242; quiz 243; DOI: 10.3928/21650799-20120426-73

ABSTRACT:

Widely used around the world, pesticides play an important role in protecting health, crops, and property. However, pesticides may also have detrimental effects on human health, with young children among the particularly vulnerable. Recent research suggests that even low levels of pesticide exposure can affect young children’s neurological and behavioral development. Evidence shows a link between pesticides and neonatal reflexes, psychomotor and mental development, and attention-deficit hyperactivity disorder. Implications include a need for improved risk assessment and health histories by clinicians, greater education at all levels, more common use of integrated pest management, and continued policy and regulatory strategies to mitigate the effects of and the need for pesticides. FULL TEXT

Aylward et al., 2010

Aylward, Lesa L., Morgan, Marsha K., Arbuckle, Tye E., Barr, Dana B., Burns, Carol J., Alexander, Bruce H., & Hays, Sean M.; “Biomonitoring data for 2,4-dichlorophenoxyacetic acid in the United States and Canada: Interpretation in a public health risk assessment context using biomonitoring equivalents;” Environmental Health Perspectives, 2010, 118, 177-181; DOI: 10.1289/ehp.0900970.

ABSTRACT:

BACKGROUND: Several extensive studies of exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) using urinary concentrations in samples from the general population, farm applicators, and farm family members are now available. Reference doses (RfDs) exist for 2,4-D, and Biomonitoring Equivalents (BEs; concentrations in urine or plasma that are consistent with those RfDs) for 2,4-D have recently been derived and published.

OBJECTIVE: We reviewed the available biomonitoring data for 2,4-D from the United States and Canada and compared them with BE values to draw conclusions regarding the margin of safety for 2,4-D exposures within each population group.

DATA SOURCES: Data on urinary 2,4-D excretion in general and target populations from recent published studies are tabulated and the derivation of BE values for 2,4-D summarized.

DATA SYNTHESIS: The biomonitoring data indicate margins of safety (ratio of BE value to biomarker concentration) of approximately 200 at the central tendency and 50 at the extremes in the general population. Median exposures for applicators and their family members during periods of use appear to be well within acute exposure guidance values.

CONCLUSIONS: Biomonitoring data from these studies indicate that current exposures to 2,4-D are below applicable exposure guidance values. This review demonstrates the value of biomonitoring data in assessing population exposures in the context of existing risk assessments using the BE approach. Risk managers can use this approach to integrate the available biomonitoring data into an overall assessment of current risk management practices for 2,4-D.

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Hart et al., 2005

Hart, L. G., Larson, E. H., & Lishner, D. M.; “Rural definitions for health policy and research;” American Journal of Public Health, 2005, 95(7), 1149-1155; DOI: 10.2105/AJPH.2004.042432.

ABSTRACT:

The term “rural” suggests many things to many people, such as agricultural landscapes, isolation, small towns, and low population density. However, defining “rural” for health policy and research purposes requires researchers and policy analysts to specify which aspects of rurality are most relevant to the topic at hand and then select an appropriate definition. Rural and urban taxonomies often do not discuss important demographic, cultural, and economic differences across rural places-differences that have major implications for policy and research. Factors such as geographic scale and region also must be considered. Several useful rural taxonomies are discussed and compared in this article. Careful attention to the definition of “rural” is required for effectively targeting policy and research aimed at improving the health of rural Americans. FULL TEXT

Shealy et al., 1996

Shealy, Dana B., Bonin, Michael A., Wooten, Joe V., Ashley, David L., Needham, Larry L., & Bond, Andrew E.; “Application of an improved method for the analysis of pesticides and their metabolites in the urine of farmer applicators and their families;” Environment International, 1996, 22(6), 661-675; DOI: 10.1016/s0160-4120(96)00058-x.

ABSTRACT:

As the annual use of pesticides in the United States has escalated, public health agencies have become increasingly concerned about chronic pesticide exposure. However, without reliable, accurate analytical methods for biological monitoring, low-level chronic exposures are often difficult to assess. A method for measuring simultaneously the urinary residues of as many as 20 pesticides has been significantly improved. The method uses a sample preparation which includes enzyme digestion, extraction, and chemical derivatization of the analytes. The derivatized analytes are measured by using gas chromatography coupled with isotope-dilution tandem mass spectrometry. The limits of detection of the modified method are in the high pg/L – low μg/L range, and the average coefficient of variation (CV) of the method was below 20% for most analytes, with approximately 100% accuracy in quantification. This method was used to measure the internal doses of pesticides among selected farmer applicators and their families. Definite exposure and elimination patterns (i.e., an increase in urinary analyte levels following application and then a gradual decrease to background levels) were observed among the farmer applicators and many of the family members whose crops were treated with carbaryl, dicamba, and 2,4-D esters and amines. Although the spouses of farm workers sometimes exhibited the same elimination pattern, the levels of the targeted pesticides or metabolites found in their urine were not outside the ranges found in the general U.S. population (reference range). The farmer applicators who applied the pesticides and some of their children appeared to have higher pesticide or metabolite levels in their urine than those found in the general U.S. population, but their levels were generally comparable to or lower than reported levels in other occupationally exposed individuals. These results, however, were obtained from a nonrandom sampling of farm residents specifically targeted to particular exposures who may have altered their practices because they were being observed; therefore, further study is required to determine if these results are representative of pesticide levels among residents on all farms where these pesticides are applied using the same application techniques. Using this method to measure exposure in a small nonrandom farm population allowed differentiation between overt and background exposure. In addition, the important role of reference-range information in distinguishing between various levels of environmental exposure was reaffirmed. FULL TEXT

Harris et al., 2010

Harris, S. A., Villeneuve, P. J., Crawley, C. D., Mays, J. E., Yeary, R. A., Hurto, K. A., & Meeker, J. D.; “National study of exposure to pesticides among professional applicators: an investigation based on urinary biomarkers;” Journal of Agricultural and Food Chemistry, 2010, 58(18), 10253-10261; DOI: 10.1021/jf101209g.

ABSTRACT:

Epidemiologic studies of pesticides have been subject to important biases arising from exposure misclassification. Although turf applicators are exposed to a variety of pesticides, these exposures have not been well characterized. This paper describes a repeated measures study of 135 TruGreen applicators over three spraying seasons via the collection of 1028 urine samples. These applicators were employed in six cities across the United States. Twenty-four-hour estimates (mug) were calculated for the parent compounds 2,4-D, MCPA, mecoprop, dicamba, and imidacloprid and for the insecticide metabolites MPA and 6-CNA. Descriptive statistics were used to characterize the urinary levels of these pesticides, whereas mixed models were applied to describe the variance apportionment with respect to city, season, individual, and day of sampling. The contributions to the overall variance explained by each of these factors varied considerably by the type of pesticide. The implications for characterizing exposures in these workers within the context of a cohort study are discussed. FULL TEXT

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