Pesticides and public health: integrated methods of mosquito management.
(49/1375)
Pesticides have a role in public health as part of sustainable integrated mosquito management. Other components of such management include surveillance, source reduction or prevention, biological control, repellents, traps, and pesticide-resistance management. We assess the future use of mosquito control pesticides in view of niche markets, incentives for new product development, Environmental Protection Agency registration, the Food Quality Protection Act, and improved pest management strategies for mosquito control. (+info)
Dermal in vitro penetration of methiocarb, paclobutrazol, and pirimicarb: effect of nonylphenolethoxylate and protective gloves.
(50/1375)
Dermal exposure has become the major route of human occupational exposure to pesticides. Detergents are used as part of formulated pesticide products and are known to change the barrier properties of human skin in vitro. However, studies on the influence of detergents as well as protective glove materials on dermal penetration of pesticides are scarce. In an experiment using in vitro static diffusion cells mounted with human skin, we evaluated the effect of nonylphenol-ethoxylate on dermal penetration of three extensively used pesticides--methiocarb, paclobutrazol, and pirimicarb--and the protection against dermal penetration offered by protective gloves made of latex or nitrile. There was a general tendency, though not statistically significant for all pesticides, for nonylphenolethoxylate to decrease the percutaneous penetration of the three pesticides. The nitrile generally offered better protection against percutaneous penetration of pesticides than did latex, but the degree of protection decreased over time and depended on the pesticides used. (+info)
Longitudinal investigation of dietary exposure to selected pesticides.
(51/1375)
Between September 1995 and September 1996, 4-day composite duplicate plate samples (379 solid food samples and 303 beverage samples) were obtained from a stratified random sample of 75 individuals in Maryland and analyzed for the presence of 10 pesticides. Samples were collected in each of six approximately equally spaced cycles as part of a larger pilot investigation of longitudinal exposure to pesticides and other elements. Chlorpyrifos was detected in 38.3% of the solid food samples, malathion in 75.2%, and p,p'-DDE in 21.4%. Other pesticides were detected in less than 10% of the solid food samples. Pesticide residues were not detected in duplicate beverage samples. In solid food samples, the mean concentration of chlorpyrifos was 0.7 (SD 1.7) microg/kg, 1.8 (2.1) for malathion, and 0.2 (0.6) for p,p'-DDE. The detection rate and mean concentration of chlorpyrifos, malathion, and p,p'-DDE varied by a factor of 2-3 among sampling cycles and significantly according to results from several statistical analyses. Co-occurrence of chlorpyrifos and malathion in solid food samples was found relatively frequently and also varied with time. Pesticides were detected in food samples with greatest frequency in spring and summer months and with lowest frequency in winter months. These results support the hypothesis that 4-day average exposure to chlorpyrifos and malathion varies over time for this population mean and for individual members of the population and that correlation between exposures to these two organophosphate pesticides can occur. The measurements of pesticide levels in duplicate plate samples presented here can be used to evaluate and set parameters for dietary exposure models. (+info)
Analytical method development for 18 pesticides in house dust and settled residues using SEC, SPE, TMS methylation, and GC-MS.
(52/1375)
An analytical method is developed to analyze eighteen pesticides in carpet dust and also dust that has settled on surfaces in order to determine the potential exposure of children to pesticide residues. For nonacid pesticides, the extract after centrifugation and filtration is cleaned up using size-exclusion chromatography (SEC) and then analyzed by gas chromatography (GC) coupled with a mass spectrometer (MS). The best solvent for extraction is ethyl acetate-cyclohexane (3:1). The recoveries of spiked nonacid pesticides from 2 g of dust are between 72% and 110% with a variation between 4.2% and 25.6%, and the detection limit is 10 to 50 ng/g dust, depending on the pesticide. For acid pesticides, the dust is extracted with a saturated Ca(OH)2 solution, centrifuged, cleaned up by polyvinylbenzene/polystyrene-type solid-phase extraction cartridges, and methylated with trimethylsilyldiazomethane (TMS). Acid pesticides on filter paper samples are extracted with acidified acetone (3 mM H3PO4) and methylated with TMS. Methylation with TMS is fast and easy to perform. Methyl esters of the pesticides are completely separated and detected at low levels by GC-MS in the selective ion monitoring mode. The average recoveries of pesticides from 2 g of dust are between 81% and 104%. The average recoveries of pesticides spiked on filter paper are between 88% and 113%. A capillary column with a stationary phase of trifluoropropylmethyl polysiloxane gives the best separation and sensitivity for most pesticides on the GC-MS. (+info)
Odor-associated health complaints: competing explanatory models.
(53/1375)
Physical symptoms may be reported in workplace and community settings in which odorous airborne chemicals are present. Despite the relative frequency of such reports, clinicians, public health authorities and sensory scientists often experience difficulty interpreting odor-associated symptoms. The approach to interpretation advocated in this review involves: (i) understanding the toxicology of the agent(s) involved (in particular their relative irritant and odorant potencies); (ii) assessing exposure parameters (i.e. concentration and duration). Depending upon exposure concentration, duration and relative irritant and odorant potencies, a variety of pathophysiological mechanisms may be invoked in explaining odor-associated health symptoms. Some of these imputed mechanisms fall under the traditional scope of toxicology and others involve attitudinal and/or behavioral responses to odors. (+info)
Could pesticide toxicology studies be more relevant to occupational risk assessment?
(54/1375)
Pesticide toxicology study design has evolved from concern for oral exposure via food residues. The emphasis on the oral route does not generally apply to workers that are exposed primarily via the dermal route either handling pesticides or re-entering treated fields. As a result numerous assumptions about how oral toxicology results relate to dermal exposure must be made when conducting worker risk assessments. These assumptions introduce a high degree of uncertainty. Alternative toxicology study designs are suggested to reduce uncertainty when assessing risk. Because the dermal route is so important to characterizing occupational risk, methods to improve the accuracy of dermal absorption estimates are suggested, including the use of human subjects to study dermal absorption. Additional suggestions include tailoring dermal, oral and inhalation kinetic study designs to reflect worker exposure dosages. Suggestions are made to routinely conduct a single dose toxicity study patterned after the neurotoxicity study design to distinguish single dose effects and NOAELs from those resulting from multiple doses. Finally, interspecies pharmacokinetics studies are proposed to determine which toxicology study regimen of dosing best reflects intermittent worker exposure. (+info)
Critique of the paper: could pesticide toxicology studies be more relevant to occupational risk assessment? (by Ross et al., 2001).
(55/1375)
The toxicology studies required for the registration of a pesticide are not necessarily well adapted to user safety assessment. This problem can be overcome in some cases by improving the guideline studies. In other cases the guidelines are based on animal models which are poor models for man; the most obvious example is rat percutaneous penetration. In other cases it may simply be impractical to have a model which can be extrapolated to all exposure situations. This is the case for intermittent exposure which is infinitely variable. The general conclusion is that the entire data package should be re-examined to make it more relevant to risk assessment. (+info)
Refinement of risk assessment of dermally and intermittently exposed pesticide workers: a critique.
(56/1375)
The regulatory requirements for the registration of pesticides are mainly evolved from concern about dietary exposure and risk, i.e. chronic oral exposure. Pesticide workers, however, are predominantly exposed dermally and intermittently. The present critique provides suggestions for improvement of toxicity studies to refine the risk assessment of pesticide workers. In this respect it is considered of utmost importance that toxicity studies (either toxicokinetic or toxicodynamic) should be tuned towards the anticipated exposure scenario. Apart from suggestions for improvement of dermal toxicokinetic and dynamic studies, recommendations for further research and guidance are given, amongst which the request for information on the robustness of in vitro dermal absorption studies and guidance on how to use these data. With respect to the intermittent exposure of pesticide workers it is recognised that both information on the anticipated exposure scenario as well as knowledge on the effect of intermittent exposure on the toxicity are needed. From a toxicological point of view, the setting of more than one Acceptable Operator Exposure Level (AOEL), covering effects that may arise after different periods of exposure, as well as the development of more robust acute and short term studies are strongly recommended. (+info)