Statement

Phthalates Study Authors Note Results "Not Straightforward"

ARLINGTON, VA (Nov. 16, 2009) – Acknowledging that their results are “not straightforward,” the authors of a new study published in the International Journal of Andrology nevertheless attempt to link reduced masculine play in boys, as reported by their mothers, to maternal exposure to phthalates.  The researchers, led by Dr. Shanna Swan, asked mothers who had participated in a previous, and much publicized, study of phthalate exposure to evaluate the play habits of their sons, aged 3 1/2 to 6 years old.

The mothers used a standard questionnaire – the Preschool Activities Inventory (PSAI) – but the questions and the results were adjusted by Dr. Swan and her colleagues to incorporate parental attitudes about male behavior.  The authors note that such adjustments “have not been used previously” in evaluating PSAI results and “remain to be validated.”

The study found an association between reduced masculine behavior and some, but not all, metabolites of dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP).  Dr. Swan has previously reported sexual morphological differences in these boys, as infants, but these findings have never been replicated or verified by other researchers.

The following statement can be attributed to Steve Risotto, Senior Director, Phthalate Esters, American Chemistry Council.

“This study shows once more that Dr. Swan uses unproven methods to compile questionable data to reach conclusions that are consistent with her well-publicized opinion, which is not based on the weight of the scientific evidence surrounding the safety of phthalates.  Dr. Swan’s recognition that the study results are ‘not straightforward’ is an understatement.  The researchers biased the results by using mothers from their previous study.  These mothers may have had much higher levels of concern about their young boys’ behavior, because Dr. Swan has repeatedly declared that phthalate exposure is reason for alarm.

“It appears that the researchers selectively excluded data, eliminating certain subjects from the analysis, in order to strengthen their conclusion.  Even the phraseology of the paper is more sensationalistic than scientific.”

Learn more about phthalates.