The Case of BPA or Bisphenol A - a Plastic Ingredient
Posted on 16 Apr, 2008

What is Bisphenol A?

Bisphenol A (BPA) is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. It exists at room temperature as a white solid and has a mild “phenolic” or hospital odor. Polycarbonate plastics are typically clear & hard & have many applications including use in certain food and drink packaging, e.g., water and infant bottles, compact discs, impact-resistant safety equipment, and medical devices. Polycarbonate plastic can also be blended with other materials to create molded parts for use in mobile phone housings, household items, and automobiles. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some polymers used in dental sealants or composites contain bisphenol A-derived materials.

The Concern

According to media reports on April 15, 2008, the Canadian government is said to be ready to declare as toxic a chemical, called bisphenol-A or BPA, widely used in food & beverage containers. Health Canada could make such an announcement before the end of May, making Canada the first country to find that bisphenol-A has human health risks.

A draft report (April 14, 2008) from the U.S. Department of Health and Human Services’ National Toxicology Program (NTP), released on April 15, endorsed a scientific panel’s finding that there was “some concern” about neural & behavioral changes in humans who consume BPA. The following are conclusions from the NTP draft report:

• There is some concern for neural and behavioral effects in fetuses, infants, and children at current human exposures. The NTP also has some concern for bisphenol-A exposure in these populations based on effects in the prostate gland, mammary gland, and an earlier age for puberty in females.

The scientific evidence that supports a conclusion of some concern for exposures in fetuses, infants, and children comes from a number of laboratory animal studies reporting that “low” level exposure to bisphenol-A during development can cause changes in behavior and the brain, prostate gland, mammary gland, and the age at which females attain puberty. These studies only provide limited evidence for adverse effects on development and more research is needed to better understand their implications for human health. However, because these effects in animals occur at bisphenol-A exposure levels similar to those experienced by humans, the possibility that bisphenol A may alter human development cannot be dismissed.

• The NTP has negligible concern that exposure of pregnant women to bisphenol A will result in fetal or neonatal mortality, birth defects or reduced birth weight and growth in their offspring.

In laboratory animals, exposure to very high levels of bisphenol-A during pregnancy can cause fetal death and reduced birth weight and growth during infancy. These studies provide clear evidence for adverse effects on development, but occur at exposure levels far in excess of those experienced by humans. Two recent human studies have not associated bisphenol-A exposure in pregnant women with decreased birth weight or several other measures of birth outcome. Results from several animal studies provide evidence that bisphenol A does not cause birth defects such as cleft palette, skeletal malformations, or grossly abnormal organs.

• There is negligible concern that exposure to bisphenol-A causes reproductive effects in non-occupationally exposed adults and minimal concern for workers exposed to higher levels in occupational settings.

Data from studies in humans are not sufficient to determine if bisphenol A adversely affects reproduction when exposure occurs during adulthood. A number of studies, when considered together, suggest a possible effect on reproductive hormones, especially in men exposed to higher levels of bisphenol A in the workplace. Laboratory studies in adult animals show adverse effects on fertility, estrous cycling, and the testes at exposure levels far in excess of those experienced by humans. A number of other effects, such as decreased sperm counts, are reported for the reproductive system at lower doses in animals exposed only during adulthood, but these effects have not been shown to be reproducible. Laboratory animal studies consistently report that bisphenol-A does not affect fertility.