Measurement of atmospheric concentrations of common household pesticides: A pilot study

Pesticides Exposure-Induced Changes in Brain Metabolome: Implications in the Pathogenesis of Neurodegenerative Disorders

Pesticides have been used in agriculture, public health programs, and pharmaceuticals for many decades. Though pesticides primarily target pests by affecting their nervous system and causing other lethal effects, these chemical entities also exert toxic effects in inadvertently exposed humans through inhalation or ingestion. Mounting pieces of evidence from cellular, animal, and clinical studies indicate that pesticide-exposed models display metabolite alterations of pathways involved in neurodegenerative diseases. Hence, identifying common key metabolites/metabolic pathways between pesticide-induced metabolic reprogramming and neurodegenerative diseases is necessary to understand the etiology of pesticides in the rise of neurodegenerative disorders. The present review provides an overview of specific metabolic pathways, including tryptophan metabolism, glutathione metabolism, dopamine metabolism, energy metabolism, mitochondrial dysfunction, fatty acids, and lipid metabolism that are specifically altered in response to pesticides. Furthermore, we discuss how these metabolite alterations are linked to the pathogenesis of neurodegenerative diseases and to identify novel biomarkers for targeted therapeutic approaches.

Chlordane and heptachlor are metabolized enantioselectively by rat liver microsomes

Chlordane, heptachlor, and their metabolites are chiral persistent organic pollutants that undergo enantiomeric enrichment in the environment. This study investigated the enantioselective metabolism of both chlordane isomers and heptachlor, major components of technical chlordane, by liver microsomes prepared from male rats treated with corn oil (CO) or inducers of CYP2B (PB; phenobarbital) and CYP3A enzymes (DX; dexamethasone), isoforms induced by chlordane treatment. The extent of the metabolism of all three parent compounds was dependent on the microsomal preparation used and followed the rank order PB > DX > CO. The mass balances ranged from 49 to 130% of the parent compound added to the microsomal incubations. Both cis- and trans-chlordane were enantioselectively metabolized to oxychlordane (EF = 0.45-0.89) and 1,2-dichlorochlordene (EF = 0.42-0.90). Heptachlor was metabolized enantioselectively, with heptachlor epoxide B (EF = 0.44-0.54) being the only metabolite. Interestingly, the direction on the enrichment for oxychlordane, 1,2-dichlorochlordene, and heptachlor epoxide differed depending on the microsomal preparation. These findings demonstrate that the direction and extent of the enantioselective metabolism of both chlordane isomers and heptachlor is P450 isoform-dependent and can be modulated by the induction of P450 enzymes.

Semivolatile organic compounds in residential air along the Arizona-Mexico border

Concerns about indoor air quality and the potential effects on people living in these environments are increasing as more reports about the toxicities and the potential indoor air exposure levels of household-use chemicals and chemicals from housing and fumishing manufacture in air are being assessed. Gas chromatography/mass spectromery was used to confirm numerous airborne contaminants obtained from the analysis of semipermeable membrane devices deployed inside of 52 homes situated along the border between Arizona and Mexico. We also describe nontarget analytes in the organochlorine pesticide fractions of 12 of these homes; this fraction is also the most likely to contain the broadest scope of bioconcentratable chemicals accumulated from the indoor air. Approximately 400 individual components were identified, ranging from pesticides to a wide array of hydrocarbons, fragrances such as the musk xylenes, flavors relating to spices, aldehydes, alcohols, esters and phthalate esters, and other miscellaneous types of chemicals. The results presented in this study demonstrate unequivocally that the mixture of airborne chemicals present indoors is far more complex than previously demonstrated.

Levels of pesticides and polychlorinated biphenyls in selected homes in the Bangkok metropolitan region, Thailand

Past uses of hazardous chemicals in Thailand for agricultural and household purposes have resulted in their ubiquity in the environment. This study aims to characterize the levels of 41 target chemicals, including 25 organochlorine pesticides (OCP), of which 17 are persistent organic pollutant (POP) pesticides, 7 pyrethroids, and 9 polychlorinated biphenyls (PCBs) in 8 homes in the Bangkok Metropolitan Region (BMR). The study is the first of these types for Thailand, and was conducted during the dry season of 2006-2007. Samples were collected at three areas of the BMR, including urban, suburban, and rural for indoor and outdoor (I/O) air, as well as from deposits on floor surfaces. Airborne samples were taken over 24 h for both the gaseous and particulate matter phases and analyzed separately by GC-ECD following the U.S. EPA TO-10A method. Overall 35 out of 41 compounds were detected in the samples. The compounds were mostly detected and at higher levels in the gas phase, except for a few less volatile compounds, such as pyrethroids or DDT. Indoor air concentrations are higher than the outdoor levels for most chemicals; hence, the I/O ratios are mostly above 1.0, especially for rural homes. Among the OCPs, heptachlor was found at the highest concentrations for urban homes (5.2 +/- 3.1 ng/m(3) indoor and 2.6 +/- 0.4 ng/m(3) outdoor). PCB profiles were dominated by the lighter congeners, with the highest levels found for PCB31 (10.4 indoors in urban homes (ng/m(3))). Suspended matters were found to be high indoors in the rural homes, which may be linked to high-strength of indoor sources.

Seasonal deposition of housedusts onto household surfaces

Seasonal differences in the particle size fractions and mass loadings of household dust deposited on indoor surfaces were examined in four New Jersey homes. Housedust was collected during a 30-day period on non-electrostatic polyethylene sample plates on which a glass slide had been placed. In each home two samples were collected at a height of 1.5 m and two were collected at a height of 0.3 m above the floor. Dust samples were obtained from each home during a summer and winter collection period. Particle size measurement was completed using an adaptation of a Meridian ACAS 570 Interactive Laser Cytometer. Results indicated that the dust mass deposited on household surfaces during the summer was greater than during the winter. The arithmetic mean mass deposition rate for all houses was 0.37 +/- 0.13 microgram/cm2/day during the summer and 0.22 +/- 0.13 microgram/cm2/day during the winter. The total number of particles deposited, however, was greater during the winter than during the summer. The increase in winter time particle number was caused by greater numbers of particles with an equivalent spherical diameter < 2.5 microns. The most probable source of these particles was winter time combustion emissions within the residences and the subsequent particle deposition on household surfaces. The greater mass loadings measured on the low sampling plates during the summer were associated with a greater number of particles with an equivalent spherical diameter > 5 microns. In the winter, however, the particle mass and number loadings were similar at both heights. These results suggested that ventilation of the house during the summer allowed resuspended particles to enter which led to the higher levels of settled dust. Measurement of contaminant levels in housedust for exposure estimation therefore, should account for the seasonal and height differences in dust mass, and collect representative fractions of housedust that are available for human contact. Furthermore, since over 99% of the particles on indoor surfaces were < 50 microns any indirect sampling technique for dermal exposure estimation should have collection efficiencies similar to the hand of particles < 50 microns.

Non-occupational exposures to pesticides for residents of two U.S. cities

The Non-Occupational Pesticide Exposure Study, funded by the U.S. Environmental Protection Agency, was designed to assess total human exposures to 32 pesticides and pesticide degradation products in the non-occupational environment; however, the study focused primarily on inhalation exposures. Two sites--Jacksonville, Florida (USA) and Springfield/Chicopee, Massachusetts (USA)--were studied during three seasons: Summer 1986 (Jacksonville only), Spring 1987, and Winter 1988. Probability samples of 49 to 72 persons participated in individual site/seasons. The primary environmental monitoring consisted of 24-hr indoor, personal, and outdoor air samples analyzed by gas chromatography/mass spectrometry and gas chromatography/electron capture detection. Indoor and personal air concentrations tended to be higher in Jacksonville than in Springfield/Chicopee. Concentrations tended to be highest in summer, lower in spring, and lowest in winter. Indoor and personal air concentrations were generally comparable and were usually much higher than outdoor air concentrations. Inhalation exposure exceeded dietary exposure for cyclodiene termiticides and for pesticides used mainly in the home. Dietary exposures were greater for many of the other pesticides. Inhalation risks were uncertain for termiticides (depending on rates of degradation) but were negligible for other pesticides. The data were insufficient to support risk assessments for food, dermal contact, or house dust exposures.

Evaluation of methods for monitoring the potential exposure of small children to pesticides in the residential environment

A nine-home pilot study was conducted to evaluate monitoring methods in the field that may be used to assess the potential exposures of children aged 6 months to 5 years to pesticides found in the home environment. Several methods, some of which were newly developed in this study, were tested for measuring pesticide residues in indoor air, carpet dust, outdoor soil, and on the children's hands. Information was also collected on household characteristics, pesticides used and stored at the residence, and children's activities. Pesticides were detected at all nine study homes. With the exception of one home, at least one pesticide was detected in all matrices sampled at each house. Of the 30 target pesticides, 23 were detected during the study. The most frequently detected pesticides were chlordane, chlorpyrifos, dieldrin, hepatachlor, and pentachlorophenol. The greatest number of pesticides and highest concentrations were found in carpet dust. The results of these investigations will be discussed in terms of performance of the methods and the distribution of pesticides across the various media sampled.