"EPA certainly has been moving in the direction of cumulative risk assessment, largely for chemicals structurally similar and ones that act in a similar way. This is the next step--focusing on adverse outcomes," she said.

"This committee believed very strongly that the conceptual approach should be broadly applicable" to other chemicals, too, she added.

For instance, EPA could evaluate the risk of combined exposures to lead, mercury, and polychlorinated biphenyls—all of which can damage developing brains and reduce children's IQs, the committee said.

"The question is do we have enough data on the individual chemicals to put into an assessment like this.  For something like phthalates, the answer is definitively yes," Sathyanarayana said.

But, she added, "for other chemicals that have not been researched as extensively, it may be difficult to find specific information for let's say, fetal effects, and this point is highlighted in the [committee's] summary."

One example where EPA does not have enough data to combine all the compounds is nanoparticles, which used in sunscreens and a variety of consumer products, she said.

The EPA's Preuss acknowledged that "there clearly will be challenges to applying this to chemicals beyond the phthalates," even when looking at just male reproduction. His staff will have to resolve questions about how much scientific evidence is needed before including a chemical.

"We sort of have a role in the agency of doing the difficult assessments," he said. "Fitting something in like this with the current staffing we have is one of the challenges, clearly."

Sathyanarayana agreed with the committee's recommendation to group chemicals together according to what they do to the body, not just how they do it. "I think it is very important," she said. "This shift in focus could lead to a much better assessment of how mixtures affect the development of adverse health outcomes."

Beyond male reproductive health, the committee's report raises interesting questions about how Preuss' staff should determine a safe amount of many chemicals, including a long list of air pollutants that can cause the same respiratory and cardiovascular damage.

"I'm sure there will be a huge amount of discussion following up on this report about how broadly we can apply the principles they recommend," Preuss said. "I think it will be quite interesting and controversial."

This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.

2 Comments

1. 1. FatNSassy 03:51 PM 12/26/08

   It is also important to note that some of these hormones have been associated with obesity. The fact that body size is determined by calorie intake is politically expedient. It keeps the population in a state of guilt so they are more easily manipulated. But that is just not the whole story. Further research needs to be conducted into the role of endocrine disruption, early puberty and obesity.

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2. 2. don 08:57 PM 12/26/08

   Actually, when the scope of the inquiry expands to include preservatives and flavor enhancers in foodstuffs, the combinations will grow exceedingly large and unwieldy. A casual check of the contents of food for sale in most 'big box' stores will show chemicals which the producer cannot determine the reactions when combined with other foods and their chemicals. In the end, money will win.

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