Expected environmental concentration

This gives an example of fate modeling in which the risks of an insect growth inhibitor, CGA-72662, in aquatic environments were assessed using a combination of the SWRRB and EXAMS mathematical models.. Runoff of CGA-72662 from agricultural watersheds was estimated using the SWRRB model. The runoff data were then used to estimate the loading of CGA-72662 into the EXAMS model for aquatic environments. EXAMS was used to estimate the maximum concentrations of CGA-72662 that would occur in various compartments of the defined ponds and lakes. The maximum expected environmental concentrations of CGA-72662 in water were then compared with acute and chronic toxicity data for CGA-72662 in fish and aquatic invertebrates in order to establish a safety factor for CGA-72662 in aquatic environments. 

Using the following equations from Reinert ( 3 ), the expected environmental concentration in water (EECW) due to runoff into the EXAMS pond can be calculated ... 

Peterson, H.G., Boutin, C., Martin, P.A., Freemark, K.E., Ruecker, N.J. and Moody, M.J. (1994) Aquatic phyto-toxicity of 23 pesticides applied at expected environmental concentrations. Aquat Toxicol, 28, 275-292. 

AES. Exposure concentrations for AES are expected to be 0.015 mg/L, on the basis of USTEST predictions for mean-flow conditions. Because USTEST-predicted concentrations are for the mixing zone in rivers downstream from STP effluents, the model predictions do not take into account removal by sorption or biodegradation in the receiving stream. Therefore, the predicted AES exposure concentrations are the highest expected environmental concentrations. 

Geographic Information System (GIS) A system that allows for the interrelation of quality data (as well as other information) from a diversity of sources based on multilayered geographical information-processing techniques, hazard (toxic) The set of inherent properties of a stressor or mixture of stressors that makes it capable of causing adverse effects in humans or the environment when a particular intensity of exposure occurs. See also risk, hazard assessment (HA) Comparison of the intrinsic ability to cause harm with expected environmental concentration. In Europe, it is typically a comparison of predicted environmental concentration (PEC) with predicted no-effect concentration (PNEC). It is normally based on a single value for effects and exposure. It is sometimes incorrectly referred to as risk assessment. 

Hazard assessment Comparison of the intrinsic ability to cause harm with expected environmental concentration. In Europe it is typically a comparison of PEC with PNEC. It is sometimes loosely referred to as risk assessment. 

A similar application of ecotoxicological data is hazard assessment. Unlike risk assessment, hazard assessment is nonprobabilistic and relies upon indices rather than probabilities. One such index is the hazard quotient , which is the ratio of the expected environmental concentration (based upon field surveys or simulation models) divided by a benchmark concentration. The benchmark concentration is derived from some measure of toxicity such as the LC50 or no-observed-effect level. Hazard assessments are often conducted at different levels or tiers of increasing complexity and specificity if a chemical is identified as potentially hazardous by tier (the least complex and specific test), a decision is made to take action or, if more information is needed, to proceed to tier 2 tests. After tier 2 tests, a decision is made whether to take action or proceed to tier 3 tests, and so on. This process is repeated until it is decided that there is enough information to determine whether or not there is significant ecological hazard. If there is, then regulatory action is taken. 

The quotient method is simple and straightforward. The method simply divides the expected environmental concentration by the hazard... 

Parker RD, Rieder DD. The generic expected environmental concentration program, ENEEC. Part B. Users Manual Tier one screening model for aquatic pesticide exposure. Washington Environmental Fate and Effects Division, Office of Pesticide Programs, US Environmental Protection Agency, 1995. 

Table 8.5. Expected environmental concentration - terrestrial PBO in avian diet (mg PBO per kg food)...

Dynamic Energy Budget aquatic toxicity test software Expected environmental concentration European Food Safety Authority Ecological model European Union... 

Traditionally, estimation of the ecological impacts of chemical toxicants has been done by comparing individual-level endpoints of toxicity to an expected, or range of expected, environmental concentrations (Suter 1993 Klaine et al. 1996 Solomon et al. 1996 Giesy et al. 1999). However, the ability of this approach to protect threatened and endangered species has been questioned (Stark et al. 2004), and the use of population modeling has been suggested as a more feasible means to ascertain the fate of populations under stress (Nacci et al. 2005). 

Considering all the adhesives that are in use, the expected environmental concentration (PEC) is determined. The most unfavorable scenario is assumed in order to ensure that all conceivable possibilities have been taken into account (O Fig. 39.3). 

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