Establishing a threshold policy for regulating food contact materials

3 Establishing a threshold policy for regulating food contact materials 

Toxicological data have shown that carcinogenic and noncarcinogenic toxic effects caused by the ingestion of chemical substances occur in predictable dietary concentration ranges. Specifically, carcinogenic potencies are know to be lognormally distributed (Rulis, 1992). Because these potencies have a wide distribution, it is possible to 

The agency also considered the toxic effects that result from chronic exposure to chemical substances. The results of chronic oral feeding studies of 2-years duration on 220 compounds have shown that only five of the 220 chemicals exhibited toxic effects below 1 mg/kg. All five of the chemicals that were toxic at levels below 1 mg/kg, on a dietary basis, were pesticides, compounds that would, based on their pesticidal activity, be expected to be more toxic than most substances (Frawley, 1967). However, even among these 5 pesticides, none exhibited toxic effects at dietary concentrations below 0.1 mg/kg. 

On the basis of the results of these analyses, FDA concluded that the noncarcino-genic toxic effects caused by the majority of unstudied compounds would be unlikely to occur below dietary concentration of 1 mg/kg. To provide an adequate safety margin, however, the dietary concentration chosen as a level that presents no regulatory concern should be well below 1 mg/kg. Therefore, FDA established a dietary concentration of 0.5 pg/kg (0.5 ppb) as the threshold of regulation for substances used in food contact articles. A 0.5 pg/kg (0.5 ppb) threshold is 2000 times lower than the dietary concentration at which the vast majority of studied compounds are likely to cause noncarcinogenic toxic effects and 200 times lower than the chronic exposure level at which potent pesticides induce toxic effects. FDA believes that these safety margins, 

FDA also concluded that establishing a 0.5 pg/kg dietary concentration as the threshold of regulation is appropriate because it corresponds to a migration level that is above the measurement limit for many of the analytical methods used to quantify migrants from food-contact materials. Thus, decisions are usually made based on dietary concentrations that result from measurable migration into food or food-simulating solvents rather than on worst-case estimates of dietary concentration based on the detection limits of the methods used in the analysis. 

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