Environmental Health News reports on a new study published in the journal Reproductive Toxicology alleging that exposure to the phthalate DINP (di-isononylphthalate) causes developmental abnormalities in rats. To get their results, researchers had to inject the rodents with phthalate levels that were from 300 to 90,000 times greater than the exposure level found in humans. At that dosage, researchers found some evidence that female rats were behaving more like their male counterparts. Although these experiments were conducted in rats, the researchers used the results to warn about the effects of phthalates on human development — an extrapolation that is invalid and faulty. ACSH's Dr. Gilbert Ross points out that, “Such tests on rats often don’t even apply to mice, much less humans.”
Indeed, in a 2009 study, Dr. Richard Sharpe, an endocrinologist at the University of Edinburgh, analyzed phthalate exposure in monkeys — an animal obviously far more closely related to humans than rats — and found absolutely no effect on health or development.
ACSH’s Dr. Josh Bloom comments on the ‘research’: “The amounts we’re dealing with here are crazy. Even if you could assume a 1:1 correspondence between rats and humans, you would have to eat 14 pounds of phthalates per day to match the highest dose given to the rodents. I personally try to limit my intake of plasticizer to one pound per day.”
Acknowledging all this, ACSH’s Dr. Elizabeth Whelan defends the safety of phthalates and observes that “these so called ‘studies’ lack the proper scientific context and only serve to scare consumers. A vast amount of government data already exists on the safety of DINP, and we currently have no reason to believe that DINP causes harmful human health effects.”
