Public Health

Primary biliary cirrhosis linked to toxic waste sites

Last Updated: 2006-03-07 13:32:34 -0400 (Reuters Health)

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - Exposure to toxic waste may play a role in the pathogenesis of primary biliary cirrhosis (PBC), findings from a new study suggest. By contrast, primary sclerosing cholangitis (PSC) did not show a link with toxic waste.

As reported in the March issue of Hepatology, Dr. Joseph A. Odin, from the Mount Sinai School of Medicine in New York, and colleagues found increased rates of PBC near Superfund toxic waste sites in New York. A particularly large cluster of PBC cases was noted in the Staten Island borough, which also had the highest density of toxic waste sites.

The researchers investigated the association after noting that thyroid disease, which is common among PBC patients, is reportedly more prevalent near toxic waste sites. The actual and expected rates of PBC and PSC were determined for all 174 zip codes in New York and correlated with the locations of toxic waste sites.

Increased rates of PBC, but not PSC, were seen in zip codes containing or adjacent to a toxic waste site (p = 0.025).

Using special software, the researchers detected five PBC clusters: one in Staten Island, and two each in the boroughs of Brooklyn and Queens. The cluster in Staten Island reached statistical significance and was located near a toxic waste site containing volatile aromatic hydrocarbons and trichloroethylene.

"Hydrocarbon exposure may cause a loss of tolerance to certain antigens," setting in motion an autoimmune reaction that leads to PBC, Dr. Odin told Reuters Health.

"It is hard to know what percentage of PBC cases are toxin related since genetics obviously also play a role," he added. "Two-thirds of cases may be related to environmental factors, but no one really knows."

As to why no association was seen between toxic waste and PSC, Dr. Odin said "it may just be that we didn't have enough patients. So, we are a planning a bigger study to see if we can pin that down."

Hepatology 2006;43:525-531.