The Plastics Revolution

(By Julia Ewan -- The Washington Post)   |   Buy Photo

He points to a large body of studies on animals in which BPA caused alterations to the reproductive, neurological and metabolic systems. "Scientific studies on lab animals," Schade says, "show that BPA might have adverse health impacts ranging from breast and prostate cancer, thyroid disease, early puberty in girls and ADHD."

But animals are not humans, and Blakey says findings from animal studies "are often not translatable to humans."

The Coalition for Consumer Choice, an industry group made up of organizations, associations and businesses "committed to supporting the continued safe use of everyday products made from bisphenol A," adds that "human exposure levels are typically more than one million times lower than levels shown to cause no adverse effects in experiments involving multiple generations of laboratory animals."

That said, virtually any scientific investigation into the safety of suspect chemicals and drugs starts with animal models, because of ethical concerns about exposing humans to toxins. Lab work with animals has often resulted in specific recommendations related to humans.

In 2006, an independent panel of experts assembled by the NIH and the EPA looked at more than 700 BPA studies and concluded that the mechanism by which it affects cells and tissues is essentially identical in animals and humans. The panel concluded that the animal studies of BPA should be taken seriously as an indicator of potential harm to humans.

The next year, another panel -- organized by Shelby's center -- issued a far less alarming review of about 500 studies. But the panel's integrity was damaged by a finding that a company hired to compile data for the report had a conflict of interest.

Phthalate Debate

The U.S. chemical industry is more at odds with overseas practices in its use of the other controversial component of many plastics: the group of compounds called phthalates. Phthalates are banned in the manufacture of toys in most European countries. A similar ban exists in California, and 12 other states including Maryland are considering bans.

Phthalates are also known as plasticizers, chemicals that prolong the life span and durability of plastics and increase their flexibility. Like BPA, phthalates are used in hundreds of products, including vinyl floors, adhesives, food packaging, automotive parts, clothing and personal-care products such as soap, shampoo, hair spray, nail polish and underarm deodorants. According to the Food and Drug Administration, phthalates are used at low concentrations to reduce cracking of nail polish, avoid stiffness in hair sprays, and as solvents and perfume fixatives in various other products.

Within this group of chemicals, two are under particularly close scrutiny -- DEHP, found mostly in medical products, and DINP, found mostly in toys -- for their potential toxic effects on the reproductive and endocrine systems.

Again, industry representatives such as the Vinyl Institute's Blakey say "there is no proof that phthalates have ever caused harm to humans." The FDA, looking into the use of phthalates in cosmetics, reported that the data it reviewed "did not establish an association between the use of phthalates in cosmetic products and a health risk." As a result, the FDA determined there was "insufficient evidence upon which to take regulatory action."

As with BPA, the evidence is mostly limited to animal studies.

One of the few human studies, published earlier this year in the journal Pediatrics, found that the urine of infants recently exposed to baby lotion, powder and shampoo had higher levels of phthalates or their byproducts. But the study did not prove the products used were responsible for the elevated readings.