INTRODUCTION: Asthma is one of the most common chronic diseases in the United States, affecting the quality of life of at least 20 million Americans. Almost half of the affected (approximately 9.5 million) are children under the age of 18. While Hispanics overall (5.4%) had lower asthma prevalence compared to non-Hispanics (7.4%), those of Puerto Rican descent (14.5%) have a higher burden of asthma than those of Mexican descent (3.9%). AIM: The purpose of this study was to use data collected from a cohort of Puerto Rican infants born in New York City to examine associations between indoor pesticides use and wheeze and asthma in the first two years of life. The data were collected in a prospective birth cohort of Puerto Rican children born to mothers with a history of allergy or asthma. METHODS: Data analysis was conducted using SAS. Descriptive statistics were calculated and reported as percentages. Bivariate statistics were carried out to test independent associations. Logistic regression models for asthma and wheeze at each time point and generalized estimating equation (GEE) models (for wheeze at the end of the study period) were then created with adjustment of potential confounders. RESULTS: After controlling for confounders, no forms of pesticides were associated with wheeze using logistic regression and GEE. However, use of rodenticides at baseline yielded a hazardous relationship with asthma at two years of age (OR = 3.64, 95% CI = 1.26 - 10.52). DISCUSSION: The strong association with exposure to rodenticides at baseline reveals the importance of early life exposures, specifically those that occur prenatally or perinatally. Because rodenticide exposures have not been specifically identified as a possible risk factor in previous scientific literature, it is difficult to ascertain the mechanism behind exposure and asthma onset. Findings from this study and previous studies indicate that more research is needed to further elucidate the role of pesticides and physiological processes, specifically lung and immune system development, in children, especially those in highly allergenic environments.

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The use of agricultural chemicals often results in water pollution. This research, comprising three parts, was designed to investigate the role of soil and grass strips and water table management in reducing pesticide and nitrate residues in drainage waters. / The first part of the research was made on lysimeters to investigate the effects of soil and grass cover under two water table management regimes. Four treatments were involved: subsurface drainage, controlled drainage, grass cover, and bare soil. Each treatment consisted of three replicates. Contaminated water containing atrazine, metolachlor, and metribuzin residues was applied to the lysimeters and samples of drain effluent were collected. Significant reductions in pesticide concentrations were found in all treatments. / In the first year (1993), herbicide levels were reduced significantly, from an average of 250 mug/L to less than 10 mug/L. In the second year (1995), water polluted at a concentration of 50 mug/L, was applied to the lysimeters, and herbicide residues were reduced significantly to less than 1 mug/L. Subsurface drainage and grass cover lysimeters (SDG treatment) reduced herbicide concentration levels to a greater extent than the other treatments and the controlled drainage lysimeters reduced nitrate concentration levels to a greater extent than the free drainage lysimeters. / The second part of the research was a field study that reports the development and testing of an on-farm pollution control system using soil as a biological filter for trapping herbicide residues. A field site with four shallow surface ditches, underlain with four perforated drain pipes, was used to carry-out field measurements. Polluted water with concentration levels of 30 mg/L of nitrate and 100 mug/L of three commonly-used herbicides was applied to the ditches for 10 days continuously; and no water was applied for the following ten days. This cycle was repeated three times. Water samples were collected both before application and after the water came out of the drains. Herbicide levels were reduced significantly in drainage waters. The average concentration level of nitrate in drainage water was found to be 17 mg/L in comparison to 30 mg/L in applied water. Also, the bio-degradation of herbicide residues in the soil was found to occur between water applications. Thus, it appears that the system would be self-sustainable in the long term. / The third part of the research utilizes a water table model, DRAINMOD, for simulating drainage waters from agricultural land and a solute transport model, PRZM2, for simulating pesticide concentrations in the drain effluent coming out of the grass filter area. DRAINMOD was used to estimate the daily drain outflows that would occur in a 100 ha subsurface drained field in the for a 1-in-20 year annual rainfall period. It was found that 6% of the farm area could be used to bring down the concentrations in drainage water from 50 mug/L to less than 1 mug/L for the three herbicides. (Abstract shortened by UMI.)

In the last century, agricultural intensification on the Canadian prairies has resulted in increased pesticide use with the potential to expose non-target organisms to pesticides as a result of non-point source pollution. In order to minimize risk and implement programs and regulations that promote sustainable agricultural practices, information on the types of pesticides being used and their subsequent fate in soils is essential. In this study, pesticide use trends were summarized and Herbicide Risk Indicators (HRIs) were calculated for the 1996-2006 growing seasons; a time period in which genetically modified herbicide-tolerant (GMHT) crops were commercially adopted. This study also quantified the influence of soil moisture, temperature, slope position, and soil depth within the plough layer on 2,4-D [2,4-(dichlorophenoxy) acetic acid] fate in soil obtained from a cultivated undulating field in Southern Manitoba. Annual pesticide use varied slightly over the 11-year period, but overall, there were no significant increasing or decreasing temporal trends for herbicides, fungicides, or insecticides. Although the total mass of herbicides remained relatively consistent, there was a significant change in the types of herbicides applied associated with the increased adoption of GMHT-canola; the most significant trend being the increase of GLY, from 16% to 45% of the total herbicides used in 1996 to 2006, respectively. HRIs demonstrated that herbicides used in 2006, are on average, more soluble, but less persistent, less volatile, and less acutely toxic to mammals (inhalation and acceptable daily intake), aquatic invertebrates, fish and algae, than those applied in 1996. Although 2,4-D remains one of the top 10 herbicides applied to agricultural crops in Manitoba, there were no significant increasing or decreasing trends in 2,4-D use between 1996 and 2006. Results from the experimental studies revealed that 2,4-D mineralization half-lives (DT50) in soil varied from 3 days to 51 days with the total 2,4-D mineralization (MT) ranging from 5.8 to 50.9%, depending on soil moisture, temperature, slope position, and depth. Both DT50 and MT demonstrated a polynomial relationship with temperature, typical of a biological system with minimum, optimum, and maximum temperatures.

In the last century, agricultural intensification on the Canadian prairies has resulted in increased pesticide use with the potential to expose non-target organisms to pesticides as a result of non-point source pollution. In order to minimize risk and implement programs and regulations that promote sustainable agricultural practices, information on the types of pesticides being used and their subsequent fate in soils is essential. In this study, pesticide use trends were summarized and Herbicide Risk Indicators (HRIs) were calculated for the 1996-2006 growing seasons; a time period in which genetically modified herbicide-tolerant (GMHT) crops were commercially adopted. This study also quantified the influence of soil moisture, temperature, slope position, and soil depth within the plough layer on 2,4-D [2,4-(dichlorophenoxy) acetic acid] fate in soil obtained from a cultivated undulating field in Southern Manitoba. Annual pesticide use varied slightly over the 11-year period, but overall, there were no significant increasing or decreasing temporal trends for herbicides, fungicides, or insecticides. Although the total mass of herbicides remained relatively consistent, there was a significant change in the types of herbicides applied associated with the increased adoption of GMHT-canola; the most significant trend being the increase of GLY, from 16% to 45% of the total herbicides used in 1996 to 2006, respectively. HRIs demonstrated that herbicides used in 2006, are on average, more soluble, but less persistent, less volatile, and less acutely toxic to mammals (inhalation and acceptable daily intake), aquatic invertebrates, fish and algae, than those applied in 1996. Although 2,4-D remains one of the top 10 herbicides applied to agricultural crops in Manitoba, there were no significant increasing or decreasing trends in 2,4-D use between 1996 and 2006. Results from the experimental studies revealed that 2,4-D mineralization half-lives (DT50) in soil varied from 3 days to 51 days with the total 2,4-D mineralization (MT) ranging from 5.8 to 50.9%, depending on soil moisture, temperature, slope position, and depth. Both DT50 and MT demonstrated a polynomial relationship with temperature, typical of a biological system with minimum, optimum, and maximum temperatures.

Atmospheric transport and air-water exchange of organochlorine pesticides (OCPs) were investigated in temperate North America and the Arctic. OCPs studied were hexachlorocyclohexanes (HCHs, a-, b- and g-isomers), components of technical chlordane (trans- and cis-chlordane, trans-nonachlor), dieldrin, heptachlor exo-epoxide and toxaphene. Air and water samples were taken on cruises in the Great Lakes and Arctic to determine concentrations and gas exchange flux direction and magnitude. The Henry’s law constant, which describes the equilibrium distribution of a chemical between air and water, was determined for several OCPs as a function of temperature and used to assess the net direction of air-water exchange. Air samples were collected in Alabama to investigate southern U.S. sources of OCPs. Chemical markers (isomers, and enantiomers of chiral OCPs) were employed to infer sources and trace gas exchange. Elevated air concentrations of toxaphene and chlordanes were found in Alabama relative to the Great Lakes, indicating a southern U.S. source. Profiles of toxaphene compounds in air were similar to those in soil by being depleted in easily degraded species, suggesting that soil emissions control air concentrations. Gas exchange fluxes in the Great Lakes indicated near-equilibrium between air and water with excursions to net volatilization or deposition. Net volatilization of a-HCH from the Arctic Ocean was traced by evasion of non-racemic a-HCH into the atmosphere.

This study examined the exposure of the Eastern Screech-owl (Otus asio) to contaminants in apple orchards of southern Quebec. Using a worstcase scenario approach, secondary exposure to three organophosphorus insecticides, (phosmet, azinphosmethyl and phosalone), two anticoagulant rodenticides, (chlorophacinone and diphacinone), and residues of previously applied organochlorines, particularly DDT and metabolites, was assessed. Exposure to PCBs and trace metals was also considered. Small mammal species preyed upon by Screech-owls were captured in orchards for residue analysis on a continual basis for persistent compounds or after insecticide and rodenticide applications. Beginning in the winter of 2000, 98 nest boxes were constructed and installed in woods inhabited by Screech-owls, adjacent to orchards. These boxes were then repeatedly inspected for pellets and prey remains. Estimated exposure of Screech-owls 0-60 hr post-application was 0.641 mg/kg for phosmet and azinphosmethyl and 0.401 mg/kg for phosalone. Exposure to phosmet at this level may warrant concern. The acute poison zinc phosphide is now the primary means of small mammal control in the study area and the possibility of exposure to anticoagulant rodenticides is diminishing. Observed DDE residues were most elevated in the short-tailed shrew (Blarina brevicauda) and ranged from <1.00 to 26.29 ug/g (wet wt) in whole-body pools. A Screech-owl egg found in a nest box between two orchards may have been thinned by as much as 19.8%, of concern because thinning maintained at 15.0 - 20.0% has been linked to population decline. Only background levels of PCBs and trace metals were detected. Finally, over 950 Screech-owl case files were also obtained from one Canadian and seven United States wildlife rehabilitation facilities and analyzed for evidence that pesticide exposure was an underlying or contributing cause of admissions.

Aquatic plants of the family Lemnaceae (e.g., duckweed) actively uptake, metabolize, and sequester pollutants in natural and engineered wetland systems. Numerous interrelated processes contribute to pollutant removal in wetlands; of these processes, interactions between organic pollutants and aquatic plants may be least understood. Research focused on (1) understanding parameters that affected uptake of fluorinated organic pollutants by Lemnaceae, (2) identifying plant processes involved in removal of wastewater-associated organic pollutants by Lemnaceae, and (3) assessing use of Lemnaceae callus cultures in understanding toxicity and metabolism of fluorinated organic pollutants by Lemnaceae. Through active plant uptake, Lemna minor rapidly removed 13 fluorinated phenols, with pseudo-first order rate constants of 0.20±0.04 d-1 to 0.84±0.07 d-1. Uptake rates depended on substituent type (i.e., trifluoromethyl- vs. fluoro-) and position, with slowest removal rates for di-ortho-substituted fluorophenols. Uptake rates decreased with increasing concentrations of fluorinated phenols; assessments of inhibition of plant oxygen production in conjugation with concentration studies indicated that concentration affected uptake rates even when Lemnaceae was not inhibited. Additionally, temperature dependencies of fluorinated phenol uptake by Lemnaceae were well represented by Arrhenius relationships; however, effects of temperature on plant activity were also observed in trends of uptake rates with temperature. Increasing uptake with decreasing concentration and increasing temperature, in addition to effects of plant inhibition, plant activity, and sorption on uptake, strongly emphasized the importance of plant metabolism in uptake of fluorinated phenols by Lemnaceae. Active plant uptake of wastewater-associated organic pollutants affected fate of fluoxetine, triclosan, and 2,4-dichlorophenoxyacetic acid, while passive plant removal processes contributed to fate of four of six wastewater derived organic pollutants. Consequently, plant-associated processes were important components of fate for over 50% of experimental wastewater-associated organic pollutants. Furthermore, assessments with Lemnaceae callus cultures indicated that callus cultures were generally more susceptible to inhibitory responses to fluorinated phenols than were Lemnaceae plants; however, metabolism of 3-trifluormethylphenol in Lemnaceae callus cultures and plants was similar, indicating that callus cultures may be valuable in plant metabolism studies. Research advances understanding of fate of organic pollutants in wetland systems, and thus has important implications for water quality, ecosystem health, and human health.

Los pesticidas organoclorados (POCs) son compuestos altamente persistentes en el medio ambiente y dada su capacidad de acumularse en los tejidos grasos animales se biomagnifican a lo largo de la cadena trófica. Estos contaminantes ambientales son antagonistas del receptor GABAA, lo que les confiere sus propiedades convulsivas tras una intoxicación aguda. En este estudio hemos planteado la hipótesis de que la exposición prolongada al pesticida dieldrín en cultivos primarios de neuronas corticales podría alterar la funcionalidad, expresión o localización de los receptores de glutamato como consecuencia del bloqueo mantenido del receptor GABAA. La exposición durante 6 días in vitro a una concentración no citotóxica (60nM) de dieldrín produjo la internalización de los receptores NMDA que contienen la subunidad NR2B (NR1/NR2B), pero no NR2A, y disminuyó también los niveles del receptor metabotrópico de glutamato 5 (mGluR5). El tratamiento con los neuroesteroides estradiol o alopregnanolona previno la reducción de los receptores NR1/NR2B en la membrana inducida por el dieldrín. Además, la exposición prolongada a 200nM dieldrin disminuyó la expresión génica de NR2A, efecto que fue revertido sólo por alopregnanolona. En neuronas corticales maduras, el dieldrín causó el truncamiento de NR2B mediado por las calpaínas y redujo la interacción de ésta subunidad con SAP102, efecto de nuevo prevenido por alopregnanolona. A pesar de que ambas hormonas restauraron la funcionalidad del receptor NMDA, alopregnanolona (pero no estradiol) revirtió tanto la inhibición del receptor GABAA como la muerte neuronal causadas por el dieldrín. Posteriormente, estudiamos los efectos de dieldrín, endosulfán y lindano sobre los receptores de estrógenos (ER) en cultivos primarios de neuronas corticales y de células granulares de cerebelo (CGC). Todos ellos inhibieron la unión de [3H]-estradiol en ambos tipos neuronales, siendo el dieldrín en CGC aquel con mayor afinidad sobre el ER. Además, dieldrín y endosulfán causaron un aumento de la fosforilación de Akt en neuronas corticales, efecto que fue inhibido por el antagonista de ERβ, PHTPP. En cambio, la fosforilación de Akt y ERK1/2 inducida por dieldrín en CGC fue mediada por la activación múltiple de ERα, ERβ, y GPR30. El lindano inhibió el efecto del estradiol sobre estas kinasas. En neuronas corticales, los tres pesticidas activaron ERK1/2 a través de los receptores GABAA y de glutamato. La exposición a largo plazo a los POCs redujo los niveles de ERα pero no de ERβ. Finalmente, comparamos la neurotoxicidad de los POCs en CGC y neuronas corticales. El dieldrín y el endosulfán fueron más tóxicos que el lindano en ambos cultivos. Se observó también que las CGC maduras son más sensibles que las neuronas corticales a la neurotoxicidad inducida por los POCs. Por el contrario, las neuronas corticales inmaduras, especialmente las glutamatérgicas, fueron más susceptibles a la exposición prolongada a concentraciones bajas de estos pesticidas. Además, la fosforilación de Akt y ERK1/2 se vio disminuida tras 24 horas de exposición a dieldrín o endosulfan en CGC. El tratamiento con estradiol e insulina previno la muerte apoptótica mediada por caspasa-3 causada por estos pesticidas a través de la activación conjunta de ERK1/2 y Akt. Este trabajo confirma que el bloqueo permanente del receptor GABAA por dieldrín provoca una reducción de la neurotransmisión glutamatérgica, lo que podría afectar a funciones cerebrales como la memoria y el aprendizaje. Además, los POCs son capaces de mimetizar o inhibir algunas de las acciones no genómicas del estradiol, lo que puede interferir con la señalización fisiológica de esta hormona en el cerebro. Este estudio revela también la susceptibilidad específica de las neuronas glutamatérgicas frente a la exposición prolongada a estos contaminantes y desvela los mecanismos moleculares por los cuales los POCs producen la muerte de estas neuronas.

Background: Children exposed to pesticides are susceptible for neurodevelopmental disruption. Data from developing countries are scarce. Aim: Assessing long-term and recent pesticide exposure in Nicaraguan children in relation to parental pesticide use and examining potential associated neurobehavioral effects. Methods: In the first study, pre- and post-spraying urinary residues of the chlorpyrifos metabolite TCPY and diazinon metabolite IMPY were measured among 7 subsistence farmers and 10 plantation workers, and in one child per worker. In the second study, for 110 children in an agricultural village and 22 in a non-agricultural village, aged 7-9, parental pesticide use was assessed by hours of spraying and kilograms of active ingredients during pre-and-postnatal time windows, as proxies for children’s long term pesticide exposures. Urinary TCPY, 3-PBA (pyrethroid metabolite), and 2,4-D were determined in 211 samples of 74 children of the agricultural village. IQ components and total IQ (WISC-IV) were evaluated in all agricultural village children. Behavior was evaluated with the Conners’ Teacher Rating Scale-Revised: Short. Multivariate linear regression models assessed associations between long-term and recent exposure to organophosphates and pyrethroids and cognitive and behavioral scales. Results: In study 1, post-spraying urinary levels of pesticide metabolites of subsistence farmers and their children were highly correlated (r=0.85), but not those of plantation workers and their children. In study 2, a wide range of exposures was reported by parents for all pesticides and time windows. The median urinary TCPY (3.7 μg/g creatinine), 3-PBA (2.8), and 2,4-D (0.9) were comparable to other studies for TCPY and 3-PBA but high for 2,4-D. Maximum levels were the highest reported for all compounds. Prenatal use of organophosphates affected working memory, and methamidophos also verbal comprehension and total IQ. Urinary TCPY was associated with poorer working memory. Organophosphate exposures were not associated with children’s behavior. Pyrethroid exposure during the first year of life associated with poorer perceptual reasoning and behavior, and urinary 3-PBA with a number of cognitive functions and ADHD in girls but not in boys. Conclusion: Nicaraguan children in poor agricultural areas are highly exposed to pesticides, which is influenced by parental pesticide use in subsistence farms. Organophosphate and pyrethroid exposures adversely affect their neurobehavioral development.