June 30, 2005

PCB exposure may raise lymphoma risk

By Michelle Rizzo

NEW YORK (Reuters Health) - Results of a study hint that
exposure to PCBs (polychlorinated biphenyls) increases the risk
of the development of non-Hodgkin's lymphoma (NHL), a blood
cancer involving the lymph nodes.

The incidence of NHL has risen over the past several
decades but the reasons for this are unclear, study
investigators explain in the July issue of the journal

In a population-based, case-control study, they examined
the association between NHL risk and exposure to organochlorine
compounds using concentrations in carpet dust as an exposure
indicator. They collected carpet dust samples from the homes of
603 NHL patients and 443 controls. The subjects had owned most
of their carpets for at least 5 years.

Dr. Joanne S. Colt, of the National Institutes of Health,
Rockville, Maryland, and colleagues found that the risk of
developing NHL was 50 percent higher if any of the PCB
compounds was detected.

The greatest effects were observed for one particular PCB
compound (PCB 180), "for which NHL risk increased steadily as
dust residues of the compound increased," Colt said in an
interview with Reuters Health.

The study also provides some evidence that DDE, a breakdown
product of DDT, another organochlorine compound, contributes to
the increased risk of NHL.

"PCBs and DDT were banned in the United States in the
1970s," Colt said. "However, exposure to these compounds was
once widespread and they continue to be ubiquitous
environmental pollutants," she added. "If the association
observed in our study is real, these compounds could have
contributed to the risk of NHL observed over the past several

The authors do not believe that contaminated carpet dust is
a major route of exposure to these compounds. "However," she
added, "because these chemicals persist in carpets for many
years, their presence in carpet dust today could be indicative
of exposures that occurred many years ago."

SOURCE: Epidemiology July 2005.