Pediatricians want better chemical laws, but evidence always a problem

Toxic chemicals are endangering children, and the government isn’t doing enough to protect them—that’s the gist of a policy statement released Monday by the American Academy of Pediatrics.

The introduction begins:

“Over the past several decades, tens of thousands of chemicals have entered commerce and the environment, often in extremely large quantities (eg, multiple millions of pounds per year). There has also been an explosion of knowledge about special vulnerabilities and differential exposures that children and pregnant women have to environmental toxicants. A growing body of research indicates potential harm to child health from a range of chemical substances.”

From there, the statement makes a case that the Toxic Substances Control Act has been woefully ineffective and that the nation needs new policies -- ones that actually work to protect pregnant women and children.

The statement, with its colorful charts of chemicals detected via biomonitoring, certainly seems alarming.

And some parents, and potential parents, may want to know just which chemicals they should avoid. But “evidence” being what it is, good answers are hard to come by.

“Frankly, there are thousands of chemicals in use, and our understanding on neurotoxicity is practically zero,” said Marc Weisskopf, an environmental epidemiologist at the Harvard School of Public Health, in an interview. He did not take part in the crafting of the statement.

Knowing which ones might be neurotoxic (meaning they disrupt brain activity) or which ones might disrupt hormonal systems (think “early puberty”) is tricky because only a few chemicals have been studied very thoroughly, Weisskopf said.

A handful of chemicals, including lead, mercury and polychlorinated biphenyls [PCBs], are clearly harmful to developing children. The vast majority of chemicals, he says, have far less evidence of harm. That lack of evidence is the problem.

To assess which chemicals might pose the greatest risk to consumers, says Weisskopf, epidemiologists look at both the potential health effects and how widespread the exposure is.

Some chemicals, like bisphenol A (BPA), get attention because they are widespread in plastics, though some health agencies say the health risks are still yet unknown to warrant regulating the chemical.

The debate might come down to whether companies produce chemicals after proving they are safe—adding extra layers for bringing a product to market—or whether the burden is on researchers to show they are unsafe after the companies have already been producing it for years.

“How one approaches that aspect of uncertainty is an important issue,” says Weisskopf.

Hence the American Academy of Pediatrics demands more information. The notion of “evidence” and what should be considered as such takes a central role in the new policy statement.

The statement makes many recommendations. Among them: “The regulation of chemicals must be based on evidence. However, decisions to limit or ban chemicals or classes of chemicals from commerce or to promote the substitution of demonstrably less hazardous chemicals should be based on reasonable levels of concern and not depend on demonstrated negative health effects after release.”