Exposure assessment soil sampling

Data collection and evaluation involves characterization of the concentration of contaminants in the media (e.g., soil, groundwater, and air) at the site in question. It includes the collection of samples to characterize soil and groundwater at contaminated property. This phase of a risk assessment may be complex and require significant resources but it is critical to providing the data needed to support the exposure assessment. 

The effects of the appropriate environmental matrices (soil, water, air, biological - for biomarker or exposure assessment studies) on assay performance must be well characterized and documented. The SOP must also include the degree of quality control necessary to ensure the satisfactory performance of the method. Quality control procedures must address the required sample preparation steps, reagent stability, instrumentation, data handling and analysis. In many immunoassay SOPs that the EPA has reviewed, quality control is totally lacking or minimally addressed particularly for the sample preparations. The Agency can provide direction on what is an appropriate degree of quality control based on the objective of the method. 

Butoxyethanol was detected at a concentration of 23 g/L in a surface water sample collected in 1979 at a site in Kentucky where it has been estimated that as many as 100,000 drums of industrial waste were disposed of between 1967 and 1977 (Stonebreaker and Smith 1980). Examination of mass spectral libraries of data from water and soil samples from U.S. hazardous wasted sites taken between late 1987 and mid-1989 identified 2-butoxyethanol in 110 samples (Eckel et al. 1996). The media in which the compound was found was not indicated. No other data were found in the available literature on the levels of 2-butoxyethanol or 2-butoxyethanol acetate in surface or groundwater, or in soil or sediment such data would be useful to assess the potential for exposure from these media. The low estimated BCF and values of 2-butoxyethanol and 2-butoxyethanol acetate (see Section 5.3.1 and Tables 3-3 and 3-4), and the ease with which these compounds are metabolized in higher trophic level animals (see Section 2.3) indicate that these compounds will not biomagnify in the food chain and, consequently, that concentrations in food will be insignificant however, there may be some potential for food contamination from packaging and washing procedures (see Section 5.4.4). The minor use of 2-butoxyethanol in herbicides (see Section 4.3) may also present the potential for food contamination by this compound. 

An important issue related to evaluating health effects of PCBs in humans is exposure assessment. Exposure to PCBs has been assessed by measuring PCBs in blood, breast milk, and adipose hssue. Umbilical cord blood also has been used to estimate exposure in utero. In addition, fish consumption has been utilized as surrogate of PCB exposure in some studies, but this measure of exposure has not always been reliable. Mean serum PCB levels range from 0.9-1.5 ppb (pg/L), in recent years, in individuals who do not have diets high in fish from waters contaminated with PCBs. In the absence of human data, environmental sampling (soil, sediment, air, food, water) has also been used to estimate exposure. 

Copeland (USA) 1993 Assessment of exposures at a wood treatment site by comparing Monte Carlo analysis and EPA s Reasonable Maximum Exposed Individual (RMEI) approach Soil samples of PCDDs and PCDFs mg/kg/day... 

A baseline risk assessment is conducted to assess the potential human health and environmental impacts associated with soil contamination. The primary exposure pathways evaluated for explosives contaminated surface soils are dust inhalation, soil ingestion, and dermal absorption. Reasonable Maximum Exposure (RME) concentrations are based on the 95% upper confidence interval (UCI) on the arithmetic mean of soil sampling data. The land use scenarios quantitatively evaluated may include industrial and residential use, utilizing EPA standard default exposure parameters. 

A thorough analysis of Warynski soil samples was performed to assess the potential plant exposure to three major metal contaminants, Pb, Cd and Zn. Tables 3 and 4 describe the major metal contaminant component of the Warynski soil, displaying available fractions and soil composition differentiated by depth. 

To assess the biodegradation in the soil samples were placed in a combined land, prepared in accordance with GOST 9.060-75. Moisture and soil acidity were kept constant. Data on changes in the mass of film samples for 8 months of exposure are presented in Table 2 of Section 5.6. 

If the soil is repeatedly investigated, the optimized distance between the sampling points is sufficient for the representative characterization of the area. If a multiple of the original distance between the sampling points is taken as a basis, assessment of temporal changes of exposures of the total area as well as of individual measuring points is still possible. 

Extraction methods based on solutions of chelating agents, such as EDTA and DTPA, or salts of weak acids, such as ammonium acetate (CH3COONH4) (Lakanen and Ervio, 1971 Lindsay and Norwell, 1969), can be used to assess plant-available trace element contents of soils and to evaluate more robustly human exposure to environmental risks in an urban context. A study carried out in the main cities of Campania region in southern Italy (Albanese, 2008) demonstrated how the bioavailable concentrations of some trace elements such as Zn, Pb and Cu in soils, determined using ammonium acetate-EDTA extraction, are much lower than the elemental concentrations determined by an aqua regia extraction on the same samples (Table 8.1). 

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