Russian boys exposed to unusually high levels of polychlorinated biphenyls (PCBs) are smaller than their peers, according to a new study from Harvard School of Public Health researchers published in the January 2011 issue of Pediatrics. Boys with the highest levels of PCBs in their blood were more than an inch shorter, and averaged two points lower in body mass index (BMI), than boys from the same region with the lowest exposure levels, according to coverage in Reuters Health.

The study, which looked at almost 500 boys over three years, identified a similar association in boys with the highest exposure to dioxin, another environmental pollutant. “You’re always a little surprised to see such a dramatic effect,” lead author Jane Burns told Reuters, but added that these results are consistent with other research.

Although manufacture of PCBs was banned in 1979, they remain a public health concern because they are still present in materials produced before the ban and persist in the environment long after their release. PCBs have been linked to increased risk of cancer, type 2 diabetes, and other diseases.