Environmental toxicity studies

All pesticides that can come into contact with the environment are subject to a risk assessment. The basis for this risk assessment is provided by data from environmental fate and environmental toxicity studies, which are carried out in the laboratory or under field conditions. The fate (adsorption, degradation, and mobility) of the active substance must be studied in soil, air, water, and sediments. The laboratory studies are frequently performed with C-labeled substances to make the mass balance easier. It is important to know how a substance degrades in the environment, because sometimes the degradation products are more persistent than the parent substance. DDT, for instance, is converted to metabolites by stepwise dechlorination (Eq. 11.9). The metabolites (e.g., DDD or DDA) can be found in soil for many years after the DDT itself is degraded. 

The bioluminescence inhibition assay for acute toxicity based on the bacterium Vibrio Jischeri (formerly Photobacterium phosphoreum) is a standard eco-toxicological bioassay in Europe (DIN EN ISO 11348). Because this method is very rapid and cost-effective it has been widely used in environmental toxicity studies, e.g., routine screening of river and lake water or effluents, monitoring of bioremediated soils, or toxicity testing of chemicals [14]. 

The legislated or suggested concentration limits in the environment and those relating to human health are given in Tables 34.1 and 34.2. The results of aquatic and environmental toxicity studies conducted on MTBE are summarized in Table 34.3. 

Calculated partition coefficients can also be used gainfully in environmental toxicity studies, where the series of compounds of interest are large and relatively homogeneous. Moreover, the often high lipophilicity of some pollutants makes it difficult to measure their partition coefficients experimentally.208-2 Interesting applications of calculated log P values are apparent in the rapidly growing field of database management and combinatorial libraries. ... 

EPA. 1985b. Endosulfan technical Review of 13-week toxicity study in mice. Memorandum. Washington, DC U.S. Environmental Protection Agency, Office of Pesticides and Toxic Substances. Document no. 004733. 

Previously, we have shown that functional secretion of OPH molecules into the periplasmic space induced about 2.8-fold higher specific whole cell OPH activity [10]. From the detail reaction kinetic studies in this work, we showed that this periplasmic space-secretion strategy provided much improved bioconversion capability and efficiency ( 1.8-fold) for Paraoxon as a model organophosphate compound. From these results, we confirmed that Tat-driven periplasmic secretion of OPH can be successfully employed to develop a whole cell biocatalysis system with notable enhanced bioconversion efficiency and capability for environmental toxic organophosphates. 

Humiston CG, Frauson LO, Quast JF, et al. 1975. A 90-day oral toxicity study incorporating acrylonitrile in the drinking water of rats. Dow Chemical Company, Health and Environmental Research, Toxicology Research Laboratory, Midland, Ml. 

EPA, U.S. Environmental Protection Agency, Prenatal Developmental Toxicity Study, Health Effects Test Guidelines, OPPTS 870.3700, EPA 712-C-98-207,1998a. http //www. epa.gov/opptsfrs/OPPTS Harmonized/870 Health Effects Test Guidelines/Series/870-6300.pdf... 

Toxicology and environmental health studies often lack a firm foundation of baseline data, and the NASGLP is a perfect starting point for a baseline data survey. During the field component of the survey, the crews collected two composite samples. One represented the top 5 cm of the soil directly below the litter layer (which will include a lot of the airborne components if they are present), and a second came from the 0-30-cm interval, independent of which soil horizon this may represent. Within this interval (the active layer), most of the interactions between biota and the non-living soil components take place, and thus is the important interval for this type if study. Environment Canada s Biological Methods Division selected one of the northern New Brunswick sites to collect a bulk sample in an attempt to create reference sites across Canada for standardized toxicity test methods. 

Gorzinski SJ, Wade CE, McCollister SB, et al. 1980. Hexachloroethane results of a 16-week toxicity study in the diet of CDF Fischer 344 rats. Midland, MI Dow Chemical, Health and Environmental Sciences. 

Among all chlorophenols, 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) are listed as priority pollutants by the US Environmental Protection Agency (EPA) (IRIS electronic database) and the EU [256]. In particular, PCP has been classified as a B2 probable carcinogen for humans from animal toxicity studies and human clinical data. 

Short RD, Minor JL, Winston JM, et al. 1977. Task IV. Developmental toxicity of ethylene dibromide inhaled by rats and mice during organogenesis. Toxicity studies of selected chemicals. Washington, D C. US Environmental Protection Agency, Office of Toxic Substances. EPA-560/6-77-028. NTIS no. PB-273 267, 1-15 117-127. 

Bioavailability from Environmental Media. Chloroform is absorbed following inhalation, oral, and dermal contact. Toxicity studies of exposure to chloroform in air, water, and food demonstrated the bioavailability of chloroform by these routes. Data regarding its bioavailability from soil are lacking, but near-surface soil concentrations can be expected to be low due to volatilization (Piwoni et al. 1986 Wilson etal. 1981). 

Jorgenson TA, Rushbrook CJ. 1980. Effects of chloroform in the drinking water of rats and mice Ninety-day subacute toxicity study. Report by SRI International, Menlo Park, CA to Health Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH. 

NTP. 1995. Printed long term technical reports and short term toxicity study reports. National Toxicology Program. Management status report. Division ofToxicology research and Testing. National Institute of Environmental Health Sciences. July 7, 1995. 

The environmental risk assessment approach most commonly adopted consists of estimation of the risk quotient (RQ) (as suggested by Hernando et al. [103]), which is defined as the ratio between the environmental concentration (measured or predicted, respectively MEC and PEC) and the predicted no-effect concentration (PNEC), and can be used to collocate compounds in one of three risk bands RQ < 0.1, minimal risk to aquatic organisms 0.1 < RQ < 1, median risk and RQ > 1, high risk [103—105]. In their risk assessment calculations, [106], further to [107], estimated PNEC values at 1,000 times lower than the most sensitive species assayed, so as to take into account the effect on other, potentially more sensitive, aquatic species to those used in toxicity studies. 

Toxicity studies with mixtures have been performed for several decades. Initially, most studies were done with binary mixtures. Later, studies with defined mixtures of more than two compounds have been reported. Studies have also been performed with complex mixtures of environmental chemicals, such as exhaust condensates, in order to gain insight into the toxic effects of such a particular mixture. However, the interpretation of the toxicity seen in these latter studies is complicated because the exact composition of the mixtures is normally not known, and the real life mixtures may vary considerably in composition. Therefore, extrapolation to other situations may be difficult. This fact is often ignored for the sake of simplicity. 

Mobil Oil Corporation. TSCA sec. 8(e) Submission 8EHQ-0381-0366 Follow-up. 4 Four Week Inhalation Toxicity Study in the Rat. Prepared by Bio/dynamics, Inc, Washington, DC, Office of Toxic Substances, US Environmental Protection Agency, 1981... 

Short RD Jr, Minor JL, Ferguson B, et al Toxicity Studies of Selected Chemicals, Task I— The Developmental Toxicity of Ethylene Dibromide Inhaled by Rats and Mice During Organogenesis. Report No EPA-560/6-76-018. Washington, DC, US Environmental Protection Agency, Office of Toxic Substances, 1976... 

Monsanto Company 1-Month Rat Dermal Toxicity Study with N-Isopropylaniline. EPA Doc No 88-880000012. St Louis, MO, Monsanto Company, Environmental Health Laboratory, 1987... 

Dennis MW Acute Dermal LD o Toxicity Study E-2B, E6-B, E-8, E-14B, E-10, E-11, E-12 with cover letter dated 03/31/82. Document no. 88-8100360, Washington DC, US Environmental Protection Agency, Office of Toxic Substances, 1982... 

Bioavailability from Environmental Media. Toxicity studies in animals indicate that absorption of hexachlorobutadiene through the gastrointestinal tract, respiratory tract, and skin can occur. Studies which identify the relationship between absorption and the matrix of soils, sediments, and foods would be useful in establishing whether or not absorption is significantly affected by such factors. 

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