In a case study just published in the online journal, Environmental Health, researcherssuggest that old wood floor finishes in some Massachusetts homes may be an overlooked, yet significant, source of exposure to the now banned PCBs (polychlorinated biphenyls).
According to the Silent Spring Institute, the key finding for this area is that in homes on Cape Cod where a PCB-containing wood floor finish (Fabulon) that was sold in the 1950s and 1960s was used, residents still retained very high blood levels of PCBs almost 50 years later. PCB residue also showed up indoors in the air and dust.
This suggests that this finish still may be an important source of PCB exposure. The researchers point out that this also may include schools and public buildings.
PCBs are persistent organic pollutants identified worldwide as human blood and breast milk contaminants. They were widely used in industry as cooling and insulating fluids for electrical equipment as well as in construction and domestic products such as varnishes and caulks.
PCBs were banned in the 1970s because of their high toxicity. PCBs are associated with thyroid toxicity, effects on immune, reproductive, nervous, and endocrine systems, and cancer effects including breast cancer. Research by the Silent Spring Institute shows that current exposure from old wood floor finishes may be even more significant for some people than their diet.
Researchers Ruthann Rudel and Julia Brody of the Silent Spring Institute and Liesel Seryak, of the Ohio State University previously measured PCBs in indoor air and dust in homes in Cape Cod during 1999-2001. They found detectable levels of PCBs in almost one in three of 120 residences.
Two of the homes had much higher concentrations of PCBs than the others and these were retested to verify the initial finding. At that time they evaluated blood PCB concentrations of the residents of those homes and discovered that they also showed higher levels of PCBs in their blood serum than the 95th percentile of a representative sample of the national population.
The newt findings also disclosed tht air and dust concentrations of PCBs remained elevated over five years between initial and follow-up sampling.
The likely source of the PCBs was brought to light when a resident reported using a particular floor finish, Fabulon, in the home in the 1950s and 1960s. Researchers learned that this product contained PCBs in the past from a reference book series “Clinical Toxicology of Commercial Products” which was published at that time.
"Our findings suggest that the exposure potential posed by historic use of PCBs in building materials may be significantly underestimated," the researchers said.
(Environmental Health is an Open Access, peer-reviewed, online journal that considers manuscripts on all aspects of environmental and occupational medicine, and related studies in toxicology and epidemiology.)