I was surprised to read about the extensive research in Puerto Rico that has found a link between phthalates in plastics and premature breast development in young girls. I was under the impression that a completely different culprit, growth hormones in chickens, was established many years ago. The article indicates that the San Juan researchers even considered pesticides as a possible source of the phthalates that “mimic estrogen.” But no mention was made of the widespread use of growth hormones by Puerto Rican chicken farmers to increase productivity of this popular food. Has the Puerto Rican chicken industry been cleared, or are they paying for this study?

Eugene Phillip
Great Falls, Va.

The researchers note that a decade ago or more, growth hormones were initially suspected. However, a link could not be established: Consumption of chicken raised on such hormones was no higher in families with girls experiencing premature thelarche than in those where girls developed normally. The Environmental Protection Agency paid for the new study .—J. Raloff