Environmental fate prediction

Mackay, D., W. Y. Shiu, K. C. Ma, and S. C. Lee. 2006. Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, 2nd ed. Boca Raton, FL CRC/ Taylor Francis. This is a comprehensive series in four volumes that focuses on environmental fate prediction. These books tackle environmental fate calculations and QSAR (quantitative structure-activity relationship) plots. This shows where the chemicals will go, relative concentrations, persistence, and important intermediate transport processes. 

In Chapter 3, the distribution of enviromnental chemicals through compartments of the gross environment was related to the chemical factors and processes involved, and models for describing or predicting environmental fate were considered. In the early sections of the present chapter, the discnssion moves on to the more complex question of movement and distribntion in the living environment— within individuals, communities, and ecosystems—where biological as well as physical and chemical factors come into play. The movement of chemicals along food chains and the fate of chemicals in the complex communities of sediments and soils are basic issues here. 

Physical and Chemical Properties. The physical and chemical properties of trichloroethylene are well characterized (HSDB 1994 McNeill 1979 Windholz 1983) and allow prediction of the environmental fate of the compound. Estimates based on available constants are generally in good agreement with experimentally determined values. No additional studies are required at this time. 

As probabilistic exposure and risk assessment methods are developed and become more frequently used for environmental fate and effects assessment, OPP increasingly needs distributions of environmental fate values rather than single point estimates, and quantitation of error and uncertainty in measurements. Probabilistic models currently being developed by the OPP require distributions of environmental fate and effects parameters either by measurement, extrapolation or a combination of the two. The models predictions will allow regulators to base decisions on the likelihood and magnitude of exposure and effects for a range of conditions which vary both spatially and temporally, rather than in a specific environment under static conditions. This increased need for basic data on environmental fate may increase data collection and drive development of less costly and more precise analytical methods. 

Larson, R.J. Role of biodegradation kinetics in predicting environmental fate, in Biotransformation and Fate of Chemicals in the Aquatic Environment, Maki, A.W., Dickson, K.L., and Cairns, J., Jr, Eds., American Society of Microbiology, Washington, 1980, pp. 67-86. 

The need to balance costs against benefits both in the public and private sectors resulted in a search for methods of predicting the fate and effects of chemicals in the environment. Actual field testing of all cases of interest is both too costly and too dangerous to perform. Mathematical models, therefore, have been developed to provide descriptive tools and predictive approaches to this problem. At the symposium on which this book is based, a collection of user-oriented information was presented and covered the following aspects of environmental fate modeling ... 

CIBA GEIGY Corporation is presently using models as an aid to data interpretation for risk assessment. Our general philosophy is to use the model as an aid to risk assessment and not as a predictive tool to eliminate definitive studies. Hopefully, environmental fate models will be useful as a predictive tool as they become validated. 

Semeena VS, Lammel G (2003) Effects of various scenarios of entry of DDT and y-HCH on the global environmental fate as predicted by a multicompartment chemistry-transport model. Fresenius Environmental Bulletin 12 925-939... 

Klopffer, W., Rippen, G., Frische, R. (1982) Physicochemical properties as useful tools for predicting the environmental fate of organic chemicals. Ecotoxicol. Environ. Saf. 6, 294—301. 

Endrin ketone may react with photochemically generated hydroxyl radicals in the atmosphere, with an estimated half-life of 1.5 days (SRC 1995a). Available estimated physical/chemical properties of endrin ketone indicate that this compound will not volatilize from water however, significant bioconcentration in aquatic organisms may occur. In soils and sediments, endrin ketone is predicted to be virtually immobile however, detection of endrin ketone in groundwater and leachate samples at some hazardous waste sites suggests limited mobility of endrin ketone in certain soils (HazDat 1996). No other information could be found in the available literature on the environmental fate of endrin ketone in water, sediment, or soil. 

Physical and Chemical Properties. As reported in Section 3.2, the relevant physical and chemical properties of cyanide compounds are known. Certain physical parameters such as octanol/water partition coefficient and soil partition coefficient that are used generally for covalently bound organic compounds to predict environmental fate and transport are neither available nor useful for most of the ionic cyanide compounds. 

Physical and Chemical Properties. As seen in Table 3-2, the relevant physical and chemical properties of disulfoton are known (Bowman and Sans 1983 Domine et al. 1992 HSDB 1994 Kenaga and Goring 1980 Melnikov 1971 Merck 1989 Sanborn et al. 1977 Worthing 1987) and predicting the environmental fate and transport of disulfoton based on K°w K°<= and H is possible. 

When the rates of sorption or desorption processes are known, environmental fate modeling can provide an educated estimate and prediction on the accessibility and bioavailability of a target pollutant to a specific transport mechanism in the environment. Hence, the present chapter is an attempt to assess fate (i.e., in terms of pollutant mobility using predictive sorption or desorption coefficients) as well as effects (i. e., in terms of bioavailability) of various pollutants and to correlate these observations for development of predictive relationships. 

In summary, property-property relationships of environmental contaminates and their isomers are useful in order to estimate other isomer properties which have never been measured or are not readily available in the literature. This can be done by developing property-property regression equations for the particular isomers of interests. In addition, environmental fate and behavior of such contaminants and their isomers could also be predicted using such relation-... 

Environmental Fate. Experimental data are available regarding the transport and partitioning properties of chloroform in surface waters (Bean et al. 1985 Clark et al. 1982 Class and Ballschmidter 1986 Dilling 1977 Ferrario et al. 1985 Piwoni et al. 1986 Sawhney 1989). Chloroform partitions mainly into the atmosphere and into groundwater. Empirical measurements or model predictions on half-disappearance times in such media as soil could not be identified in the literature. Chloroform can be transported long distances in air. Data are available regarding the degradation of chloroform in the... 

A ranking of these pesticides with respect to ease of detoxification by hydrolysis can thus be used as a basis for determining treatment of drinking water, and can also be used to predict the relative environmental fate parameters. Assuming similar dependence of kgijg on 0H concentration for environmental pH values, the rankings obtained In this study can be applied to environmental conditions and can be useful for pesticide application decisions. ... 

To assess the potential environmental impact, studies on environmental fate and effects were conducted for a risk assessment. Steger-Hartmann et al. [125] calculated the predicted environmental concentration (PEC) in surface water and compared the resulting concentration of 2 g with the predicted no-effect... 

Physical and Chemical Properties. The physical and chemical property data available for 2-hexanone are sufficient to allow a limited estimation of the potential environmental fate of this chemical. The estimated Henry s law constant (Mabey et al. 1982) and K°c (Hassett et al. 1983) need to be verified experimentally to help confirm the estimates of partitioning in environmental media. Since there does not seem to be a consensus on the solubility of 2-hexanone in water (reported values range from about 20-35 g/L) (Morrison and Boyd 1974 Verschueren 1983), additional measurements would be useful to more accurately predict the environmental fate of this compound. 

O Hagan A. 2001. Uncertainty in toxicological predictions the Bayesian approach to statistics. In Rainbow PS, Hopkin SR Crane M, editors. Forecasting the environmental fate and effects of chemicals. Chichester (UK) John Wiley, p 25—41. 

---