August 1 (HealthDay News) -- Women who 32 years ago lived in the area of a major dioxin spill in Italy have been six times more likely to give birth to babies with altered thyroid function than other women, a new study reports.

The study, published in the open access journal PLoS Medicine, looks at the aftereffect of an accidental release of 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD, the most toxic dioxin known, during a 1976 incident at a chemical factory in Seveso, Italy.

Dioxins are a chemical byproduct of waste incineration that don't degrade and can accumulate in people. Previous studies have shown that women exposed to dioxins may have babies with damaged thyroid glands.

Researchers at the University of Milan found that babies born to mothers who lived in an area near the factory at the time of the disaster had high blood levels of TSH, a thyroid secreting hormone that -- in overabundance -- is associated with a failing thyroid and can cause damage to a baby's developing body and brain.

The authors said further studies on the long-term progress of the children with high TSH levels are needed to see if they have more development problems, such as reduced growth and intellectual development.

SOURCE: Harvard School of Public Health, news release, July 28, 2008