Several new studies are suggesting links between chemicals used in plastics and health problems, including childhood asthma and breast cancer.
One study published in a U.S. government journal found that phthalates used in vinyl products, cosmetics and other household goods are linked to childhood asthma, while a report from the San Francisco-based Breast Cancer Fund said studies show an increasing connection between chemical exposure and breast cancer.
Industry officials dispute the studies, saying they are either incomplete or that other evidence argues against the conclusions.
The phthalates study, published in the October issue of the journal Environmental Health Perspectives, drew a connection between plasticized products like PVC flooring and what it said is a marked increase in allergy problems reported in children in the past three decades.
``Although multiple factors likely are responsible for the increases in allergies and asthma that have been documented in developed countries over the past 30 years, it is striking that these increases have occurred during a period when plasticized products have become ubiquitous in the homes, schools, and workplaces of the developed world,'' the study concludes.
The study was led by researchers at the Swedish National Testing and Research Institute. EHP is published by the U.S. Department of Public Health and Human Services, although EHP said on its Web site that publication does not equate to endorsement by the U.S. government.
By looking at the homes of 400 Swedish children, the study said it found connections between exposure to butyl benzyl phthalate (BBzP) and rhinitis and eczema, and di(2-ethylhexyl) phthalate (DEHP) and asthma.
But other studies have not found such links, said Marian Stanley, director of the phthalate esters panel at the American Chemistry Council in Arlington, Va.
She said the science is complicated because there are no animal models for predicting asthma. Studies that have tested the hypothesis have dosed mice with both phthalates and the chemical compound linked to asthma in people, and found that while the asthma compound damages the immune system, the phthalates do not, she said.
She called the Swedish study provocative, but said it is not clear if phthalates caused the asthma, or if families with asthmatic children installed vinyl flooring because it is easy to clean. People with asthma often are urged to make their living spaces easy to clean, she said.
But the study's authors said they designed it to look for multiple health effects, and said it may underestimate the connections between phthalates and respiratory problems.
The Oct. 7 report from the Breast Cancer Fund said there is compelling evidence that some chemicals are contributing to breast cancer rates that have climbed steadily since the 1940s, although it noted that in other cases the links are not definitive.
The report said radiation exposure is the best-established environmental cause of breast cancer, but said that phthalates, bisphenol A and other chemicals used in making plastics can mimic hormones and may contribute to breast cancer.
``We look at it all as evidence, not proof,'' said Nancy Evans, editor of the Breast Cancer Fund report. ``We take a precautionary approach, which says that evidence of harm should be the trigger for action, rather than waiting for proof of harm.''
The report said researchers have speculated that widespread exposure to BPA and other chemicals ``may help explain the increase in breast cancer in industrialized countries.''
But an official with the American Plastics Council's polycarbonate unit said other studies dispute the BPA connection with breast cancer. The official also noted that a recent industry-funded study published by the Harvard Center for Risk Analysis said BPA does not appear to act like an estrogenic compound. The degree to which BPA mimics estrogen underlies much of the entire debate.
The EHP study came out as the European Union decided last month to make permanent its ban on phthalates in toys.