Yesterday, it was bad news for the boys with the release of a study that found that exposure to phthalates could lower a boy's IQ. Today the bad news continues, but this time it's girls who are in the hot seat.

Researchers at Mount Sinai School of Medicine in New York recently began investigating the use of three chemicals — phenols, phthalates and phytoestrogens — that are often found in canned food packaging as well as perfumes, lotions and shampoos. The researchers found evidence these chemicals can cause harm by interfering with the body's hormones. In a study of the effects of the three compounds on 1,151 pre-pubescent girls in the U.S., researchers found that the chemicals caused a variety of problems in puberty. 

The chemicals, which are used to increase durability in nail polishes and canned food liners, add fragrance to personal care products (such as perfumes, lotions and shampoos) and increase the flexibility of plastics such as PVC, were widely detectable in the urine samples taken from study participants.

The girls were between 6 and 8 years old when they were recruited for the study and 7 to 9 when their urine samples were analyzed for phenols, phthalates and phytoestrogens. The study, published in Environmental Health Perspectives, found links between high levels of these chemicals and early breast development. The strongest links were seen with phthalates and phytoestrogens, which were also among the most common.

Of course, as is the case with many studies, there are other factors to consider here. For instance, the researchers also found that BMI (body mass index) played a role in the onset of puberty. About a third of the girls were considered overweight, which is also an indicator of early breast development. So it's difficult to pinpoint exactly which factor (or combination of factors) was responsible for the early onset of puberty.

Researchers are continuing to study the impact of diet and chemical exposure on pubertal development and eventual breast cancer risk.