Environmental risks, analytical methods

The definitions of method detection and quantification limits should be reliable and applicable to a variety of extraction procedures and analytical methods. The issue is of particular importance to the US Environmental Protection Agency (EPA) and also pesticide regulatory and health agencies around the world in risk assessment. The critical question central to risk assessment is assessing the risk posed to a human being from the consumption of foods treated with pesticides, when the amount of the residue present in the food product is reported nondetect (ND) or no detectable residues . 

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. 

It is a regulatory requirement that analytical methods be developed to determine residues of concern in crops, feed, and food commodities as well as environmental samples (air, soil, and water). Methods for crops, feed, and food commodities are required for enforcement purposes but are also needed for a variety of other purposes, such as gathering monitoring data for risk assessment. For nearly any purpose, the methods must be robust, that is, when used by different analysts in several laboratories, they should provide reproducibly similar results. 

CPE XI returned to Cairo, Egypt in 1997, and papers and posters were presented on adsorption, analytical methods, chemical/biological/treatment, groundwater studies, ion exchange, modeling, risk assessment, waste minimization and treatment, and for the first time, ISO 14001, which focuses on environmental management and quality systems. 

The sustainable management of sediments, in addition to water, soil and sludge environmental matrices, in relation to surfactant regulations, is also an important and relevant issue. The US EPA has recently shown concern regarding the levels of surfactants in sediments and has thus released a Draft Contaminated Sediment Science Plan. In this draft, recommendations for the development of analytical methods and evaluations of the toxicity and risk assessment of Emerging endocrine disrupters like APEOs and their metabolites in sediment samples are outlined. 

EHC monographs examine the physical and chemical properties and analytical methods sources of environmental and industrial exposure and environmental transport kinetics and meta-bohsm including absorption, distribution, transformation, and elimination short- and long-term effects on animals, carcinogenicity, mutagenicity, and teratogenicity and finally, an evaluation of risks for human health and the effects on the environment. 

In the case of degradation products and metabolites, the situation is different. Generally, these compounds were not analysed because in most cases they are not regulated and no effective analytical methods exist for their determination. This means that a correct diagnosis of the environmental situation cannot be made and, as a consequence, no appropriate action can be taken. Therefore, in order to improve the risk assessment of a hazardous waste site for example, as many compounds as possible should be analysed at the beginning of the investigations (non-target analysis). 

TPH is defined as the measurable amount of petroleum-based hydrocarbon in an environmental media. It is, thus, dependent on analysis of the medium in which it is found (Gustafson 1997). Since it is a measured, gross quantity without identification of its constituents, the TPH "value" still represents a mixture. Thus, TPH itself is not a direct indicator of risk to humans or to the environment. The TPH value can be a result from one of several analytical methods, some of which have been used for decades and others developed in the past several years. Analytical methods are evolving in response to needs of the risk assessors. In keeping with these developments, definition of TPH by ATSDR is closely tied to analytical methods and their results. The ATSDR approach to assessing the public health implications of exposure to TPH is presented in Section 2.3. 

The Laboratory of Applied Analytical Chemistry at the Warsaw University, Chemistry Department works on environmental analytical chemistry, development of analytical methods for determination of trace metals in environmental samples and speciation analysis as a modem tool for environmental risk assessment. 

Toxicity studies in rodents and environmental species indicate that chronic exposure to relatively low concentrations of particularly SCCPs and MCCPs adversely affects survival and development. Much of the toxicity data on the CPs is dated, and suitable analytical methods were not available to well characterize internal doses or exposure concentrations. The development of improved analytical methods and monitoring of these heterogeneous compounds is challenging, but has certainly improved over recent years. This is essential in distinguishing the possible effects of impurities in technical CP mixtures and will aid in the accurate comparison of exposure data with hazard information based on internal dose to establish better risk characterization. 

As already stressed, these techniques involve many analytical steps such as extraction, derivatization, separation and detection, which should be performed in such a way that decay of the unstable species does not occur. However, the control of the quality of measurements is often hampered by the lack of suitable reference materials for speciation analyses. Research is hence directed towards the development of new (if possible simple) analytical methods, the production of reference materials, and the monitoring of chemical species for various purposes (environmental risk assessment, toxicity studies, biogeochemical cycles of trace elements, etc.). 

---