Thursday, October 23, 2008


Synthetic plastic materials, most of them derived from petroleum by-products, are widely used for handling of foods whether for packing, storing, cooking or equipment fabrication. Since they are made using a number of organic and inorganic ingredients, many of them with harmful effects at higher concentrations, their safety for food contact applications is of paramount importance. In India the BIS specifications for food grade plastics are mandatory to be followed by the fabricators/converters and there are well defined testing procedures to assess the suitability of these man made materials by food industry and the consumers. Global migration tests using simulating solvent systems like water, acetic acid, alcohol and heptane at different temperatures and concentrations provide vital data based on which the suitability of different plastic materials is determined.
The safety of the plastics is premised on the basis of a positive list of chemicals that are allowed in plastics and combined with the limits of migration specified, plastics are cleared for food contact applications. Specific migration limits are also set for monomers like vinyl chloride, styrene, acrylonitrile, caprolactum etc from which polymers are manufactured. Migration of color into the simulating solvents also is taken into consideration. How far this testing methods are realistic for Indian products is a moot question as these have been designed in western countries for assessing their foods. Probably they may be the best bet under the prevailing conditions in absence of any worth while data specifically on Indian foods. More uncertainty is evident when India specific foods are cooked with  microwave energy where migration as well as artifacts cannot be predicted.
Bis-Phenol A (BPA) is a chemical used in the manufacture of some plastics like poly carbonates and epoxy resins, a coating material for Aluminum and Steel cans to prevent surface reaction with the food contents. Polycarbonate has excellent clarity and transparency, almost resembling glass and was being manufactured by a small company in Canada for making laboratory wares like burrets, pippets, beakers etc. Over the years it became the most preferred plastic for making feeding bottles for infants. It was recently that traces of BPA were detected in the milk in such bottles. FDA of USA admits that small quantities are leached out into the food or milk when the polycarbonate feeding bottles are used but claims that at the concentration detected it is not dangerous. However National Toxicology Program, the Federal Agency for Toxicological Research categorically claims that BPA can adversely affect the brain development and behavior of fetuses and children. Further Yale School of Medicine showed BPA causing loss of connection between brain cells leading to memory loss, learning problems and depression in children. In rats BPA caused tumors, urinary tract problem and early puberty. Most recent studies have linked BPA to diabetes, heart disease and liver abnormalities in adults.
While alternative and safer materials will emerge eventually in place of poly carbonates for feeding bottles, the can industry finds itself in a blind to replace epoxy resins containing BPA. Tritan copolyester is now being suggested as an alternative which does not need BPA. The larger question is what ever has happened to millions of infants fed in poly carbonate bottles during the last few years who must be in the age group between 1 and 15 years by now? Probably one may never know.   

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