Carcinogenic potential, evaluation

A comprehensive search (295) of the STORET water quaUty database, maintained by the U.S. EPA Office of Water, is used to evaluate the potential water quaUty implications of various herbicides. This database contains information on contamination of surface water (SW) and groundwater (GW) suppUes. The data are provided to give a general impression of the occurrence of a given herbicide in SW and GW (269). The U.S. EPA scheme for categorizing a chemical s carcinogenic potential is used for herbicides for which healthy advisory information (HA) is available. The U.S. EPA is continually issuing HAs for various environmental contaminants HAs available in Reference 269 were used in preparation of this article. 

Considerable concern has been raised over the carcinogenic potential of 2,4-D. However, the World Health Organization (WHO) has evaluated the environmental health aspects of this chemical and concluded that 2,4-D posed an insignificant threat to the environment. They did indicate, however, that... 

The carcinogenic potential of the profiled substance is qualitatively evaluated, when appropriate, using existing toxicokinetic, genotoxic, and carcinogenic data. ATSDR does not currently assess cancer potency or perform cancer risk assessments. Minimal risk levels (MRLs) for noncancer end points (if derived) and the end points from which they were derived are indicated and discussed. 

Casto BC, Meyers J, DiPaolo JA. 1979. Enhancement of viral transformation for evaluation of the carcinogenic potential of inorganic metal salts. Cancer Res 39 193-198. 

In spite of the great effort and advances made on in vitro testing, we are still far to have alternative methods robust enough to cover developmental, neurotoxic, reproductive, or carcinogenic potential for the substances evaluated. However the use of some distinct approaches may cover a great part of the potential toxic effects of some environmental pollutants. 

Qualitative Evaluation of Carcinogenic Potential of Some PFCs Using In Silico... 

The second example focuses on qualitative evaluation of carcinogenic potential of some perfhiorinated compounds (PFCs) using both QSARs models and an in vitro cell transformation assay (CTA). 

In this chapter we will introduce and discuss the use of alternative methods to evaluate the carcinogenic potential of some PFCs. In detail, in silico (QSAR) models and BALB/c 3T3 CTA will be used to investigate the issue. 

For the in silico evaluation of carcinogenic potential of PFCs, 16 compounds were selected (see Table 2). 

Nessel, C.S., A comprehensive evaluation of the carcinogenic potential of middle distillate fuels, Drug Chem. Toxicol., 22, 165, 1999. 

In vivo testing for mutagenic potential has also not been conducted. The carcinogenic potential for hexachloroethane has only been evaluated for the oral route. 

The carcinogenic potential of hexachloroethane has not been evaluated following chronic inhalation or dermal exposure. Hexachloroethane increased the incidence of renal tumors in male rats (NTP 1989) following chronic oral exposure. However, these tumors were associated with renal hyaline droplets and, thus, are unique to male rats. Although kidney damage was present in female rats after lifetime exposures to 80 and 160 ppm hexachloroethane, there was no increase in renal tumors. Liver lesions and liver tumors were found in mice following long-term oral exposure (NTP 1977). 

Since the early 1970s, the standard for adequate evaluation of the carcinogenic potential of a candidate pharmaceutical has been the conduct of lifetime, high dose assays in two species, almost always the rat and the mouse. 

The huge advances made in molecular biology since the late 1980s have provided the possibility of approaches to evaluating chemicals and potential drugs for carcinogenic potential in approaches which are different, less expensive and which take a shorter period of time than traditional long-term bioassays. This work has also been stimulated by dissatisfaction with the performance of traditional test systems. 

The SHE cell transformation assay at pH 6.7 is conducted to determine the ability of a test article to induce morphological transformation in cultured SHE cells. The SHE cell transformation assay is one of the most widely used cell transformation assays. The endpoints of this assay are related to the conversion of normal cells into preneoplastic or neoplastic cells. The assay provides a valuable tool in the process of assessment and evaluation of the carcinogenic potential of a test article.2 28... 

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