Analytical methods for the determination of the bioaccessibility of pesticides in contaminated soils.

摘要

One of the major goals in public health is to limit the degree to which the population is exposed to hazardous substances that may have been introduced into the environment. The inadvertent ingestion of contaminated soil can be an important source of exposure to many contaminants, including pesticides. The level of a pesticide that is available for absorption into a biological system—the bioaccessible fraction—may be much lower than the overall contamination level of the soil due to the interaction of each chemical with the solid matrix. This bioaccessibility is dependent on characteristics of the chemical species of interest as well as the soil type and residence time of the compound in the soil.; In an effort to improve understanding of the aspects of soil and contaminants that affect the bioaccessibility of organic contaminants in soil, a time-based study was conducted comparing the recovery of organochlorine pesticides (OCPs) and organophosphorus pesticides (OPPs) from spiked sand, humic acid-amended sand, soil and humic acid over a period of months. Microwave assisted extraction (MAE) and Soxhlet extraction were performed on all samples. Organochlorine pesticides (DDT and chlordane) were recovered at nearly 100% over the entire time. The recovery of organophosphorus pesticides decreased over time in all media. Diazinon and malathion were recovered in lower amounts from more inorganic media than from media with higher organic content. Chlorpyrifos behaved similarly to diazinon and malathion in low organic content media and similarly to the OCPs in higher organic content media.; Total extraction methods are designed to remove all contaminants from the soil and are typically conducted using standard analytical techniques that are optimized for the analysis of the specific contaminant under investigation. Bioavailability and bioaccessibility determinations, however, must be performed using techniques that have been specifically designed to do that task and are usually conducted using animal models. An adaptation of analytical extraction methods is presented as a possible alternative to standard bioaccessibility determinations. A combination of results from microwave assisted extraction (MAE) and aqueous microwave extraction (WME) are used to approximate the bioaccessibility of organochlorine and organophosphorus pesticides from soil and model solids.