Consumers need to look out for baby bottles and other food and beverage containers containing bisphenol A, commonly known as BPA, which has been linked to cancer and certain disorders.
BPA is usually used in the manufacture of some polycarbonate plastics, such as clear, hard water and baby bottles. Six of the largest US manufacturers of baby bottles have agreed to stop selling bottles made with BPA, but it was reported that one company will continue to market its products overseas.
Consumers are advised to opt for glass, stainless steel, or BPA-free plastic bottles which are marked with recycling codes No 1, No 2, No 5 or No 7 without the PC (polycarbonate) marking. Note: Some No. 7 plastic bottles may contained Bisphenol A properties.
About Bisphenol A (BPA)
Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several important plastics and plastic additives. With an annual production of 2–3 million metric tonnes, it is an important monomer in the production of polycarbonate.
Suspected of being hazardous to humans since the 1930s, concerns about the use of bisphenol A in consumer products grabbed headlines in 2008 when several governments issued reports questioning its safety, and some retailers pulled products made from it off their shelves.
Health effects of Bisphenol A
Bisphenol A has low acute toxicity, with an oral LD50 of 3250 mg/kg in rats, but it is an endocrine disruptor. Low doses of bisphenol A can mimic the body's own hormones, possibly causing negative health effects. There is thus concern that long term low dose exposure to bisphenol A may induce chronic toxicity in humans.
Human exposure to bisphenol A
Bisphenol A has been known to leach from the plastic lining of canned foods and, to a lesser degree, polycarbonate plastics that are cleaned with harsh detergents or used to contain acidic or high-temperature liquids. While most exposure is through diet, exposure can also occur through air and through skin absorption.
Studies by the CDC found bisphenol A in the urine of 95% of adults sampled in 1988–1994 and in 93% of children and adults tested in 2003–04. Infants fed with liquid formula are among the most exposed, and those fed formula from polycarbonate bottles can consume up to 13 micrograms of bisphenol A per kg of body weight per day (μg/kg/day; see table below). The most sensitive animal studies show effects at much lower doses, while the EPA considers exposures up to 50 µg/kg/day to be safe.
Consumer groups recommend that people wishing to lower their exposure to bisphenol A avoid canned food and polycarbonate plastic containers (which shares resin identification code 7 with many other plastics) unless the packaging indicates the plastic is bisphenol A-free. The National Toxicology Panel recommends avoiding microwaving food in plastic containers, putting plastics in the dishwasher, or using harsh detergents, to avoid leaching.
Identification in plastics
There are seven classes of plastics used in packaging applications. Type 7 is the catch-all "other" class, and some type 7 plastics, such as polycarbonate (sometimes identified with the letters "PC" near the recycling symbol) and epoxy resins, are made from bisphenol A monomer. When such plastics are exposed to hot liquids, bisphenol A leaches out 55 times faster than it does under normal conditions, at up to 32 ng/hour. (in an 8 ounce glass, boiling for an hour will give concentrations of 29 parts per trillion) Type 3 (PVC) can also contain bisphenol A as antioxidant in plasticizers.
Safe plastics
Types 1 (PET), 2 (HDPE), 4 (LDPE), 5 (polypropylene), and 6 (polystyrene) do not use bisphenol A during polymerization or package forming.
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