Structure-activity relationship analysis tools: validation and applicability in predicting carcinogens.

OncoLogic and MultiCASE (MCASE) are two structure-activity relationship (SAR) analysis software programs available to screen compounds for potential carcinogenicity. Ashby-Tennant structural alerts [Ashby, J., Tennant, R.W., 1991. Definitive relationships among chemical structure, carcinogenicity, and mutagenicity for 301 chemicals tested by the US NTP. Mutat. Res. 257, 229-306] and genetic toxicity testing may also be used to assess/predict this endpoint. Six-hundred and fifty compounds tested for carcinogenicity whose results were tabulated in the Carcinogenic Potency Database (CPDB) were used to validate and compare the predictivity of OncoLogic (Version 4.1), MCASE (Version 3.1), Ashby-Tennant structural alerts, and genetic toxicity testing, individually and in combination. The sensitivity of the methods for predicting carcinogens and the specificity for predicting non-carcinogens was examined. Potent carcinogens, defined as those with TD(50) values of less than 6.25 mg/kg bw/d, were then examined separately. It is concluded that SAR analysis programs and structural alerts perform well for compounds with low human exposure levels and have the potential to supplement the results of routinely requested genetic toxicity tests in a weight-of-evidence approach in predicting carcinogenicity, although each method of analysis has limitations regarding applicability.

Perfluorochemicals: potential sources of and migration from food packaging.

Perfluorochemicals are widely used in the manufacturing and processing of a vast array of consumer goods, including electrical wiring, clothing, household and automotive products. Furthermore, relatively small quantities of perfluorochemicals are also used in the manufacturing of food-contact substances that represent potential sources of oral exposure to these chemicals. The most recognizable products to consumers are the uses of perfluorochemicals in non-stick coatings (polytetrafluoroethylene (PTFE)) for cookware and also their use in paper coatings for oil and moisture resistance. Recent epidemiology studies have demonstrated the presence of two particular perfluorochemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human serum at very low part per billion levels. These perfluorochemicals are biopersistent and are the subject of numerous studies investigating the many possible sources of human exposure. Among the various uses of these two chemicals, PFOS is a residual impurity in some paper coatings used for food contact and PFOA is a processing aid in the manufacture of PTFE used for many purposes including non-stick cookware. Little information is available on the types of perfluorochemicals that have the potential to migrate from perfluoro coatings into food. One obstacle to studying migration is the difficulty in measuring perfluorochemicals by routine conventional analytical techniques such as GC/MS or LC-UV. Many perfluorochemicals used in food-contact substances are not detectable by these conventional methods. As liquid chromatography-mass spectrometry (LC/MS) develops into a routine analytical technique, potential migrants from perfluoro coatings can be more easily characterized. In this paper, data will be presented on the types of perfluoro chemicals that are used in food packaging and cookware. Additionally, research will be presented on the migration or potential for migration of these chemicals into foods or food simulating liquids. Results from migration tests show mg kg(-1) amounts of perfluoro paper additives/coatings transfer to food oil. Analysis of PTFE cookware shows residual amounts of PFOA in the low microg kg(-1) range. PFOA is present in microwave popcorn bag paper at amounts as high as 300 microg kg(-1).