Polychlorinated biphenyls (PCBs) were commercially manufactured in the United States from about 1930 until 1979. Then their production was banned under the Toxic Substances Control Act (TSCA) of 1976, as concerns about their extreme environmental persistence, ability to bioaccumulate, and adverse human health effects were discovered.(3)
Items containing PCBs, like carbonless carbon paper, are no longer being manufactured, but these chemicals received much attention in terms of research and removal from the environment. However, other PCBs are still produced and released into the environment. This is usually as a result of unintentional by-products of manufacturing processes including those used to make certain pigments used in dyes, inks, and paints.(4)
PCBs do not occur naturally, and once in the environment they can last for decades. PCBs are considered to be immunotoxic and affect reproduction. Adverse effects associated to the exposure of PCBs are damage to the immune system, liver, skin, reproductive system, gastrointestinal tract and thyroid gland.(5)
The effects of long-term exposure to PCBs on developmental dental defects of deciduous and permanent teeth in children in eastern Slovakia were evaluated. This area was chosen as PCBs from a chemical plant manufacturing Delors contaminated the surrounding district.(6)
Four hundred and thirty-two children aged 8–9 years were examined, and had lived in the community their entire lives. They were examined for caries susceptibility and gingival health, using standard dental indices. They also used the developmental enamel defects index from the FDI World Dental Federation (FDI). Questionnaires completed by the parents provided information on exposure and various confounding factors. No associations between PCB exposure and caries susceptibility, gingival health or number of teeth were observed in this study. The study demonstrated a dose–response relationship between PCB exposure and developmental enamel defects of permanent teeth in children, the evidence for deciduous teeth was not conclusive. (6)
Another study detected PCB 11 in ambient air in the Chicago area.(7) Superfund Basic Research Program (SBRP), a non-profit organization dedicated to providing free asthma care and education to children in underserved areas of the city, allowed this team to install high volume air sampling equipment on two health clinic vans. The equipment collected air samples at more than 37 sites in Chicago while C.A.R.E. staff provided health services to help diagnose and treat respiratory illnesses of elementary students and families.
As always, there is a need to conduct further studies on the toxicity of PCB 11.
References
1. http://www.scientificamerican.com/article/yellow-pigments-in-clothing-and-paper-contain-long-banned-chemical/.
2. Zhu, Yueming. "Polychlorinated biphenyl (PCB)-induced oxidative stress mediates cytotoxicity in human breast and prostate epithelial cells." PhD diss., University of Iowa, 2011. http://ir.uiowa.edu/etd/3026.
3. Toxic Substances Control Act (TSCA). http://www.epa.gov/agriculture/lsca.html.
4. Environmental Heath Perspectives. http://ehp.niehs.nih.gov/121-a86/.
5. Stockholm Convention. PCBs Overview. http://chm.pops.int/Implementation/PCBs/Overview/tabid/273/Default.aspx.
6. Jana J, Sovcikovab E, Kočanb A, Wsolovab L, and Trnovecb T. Developmental dental defects in children exposed to PCBs in eastern Slovakia. Chemosphere, Volume 67, Issue 9, April 2007, Pages S350–S354.
7. Hu D, Martinez A, Hornbuckle KC. Exit NIEHS 2008. Discovery of Non-Aroclor PCB (3,3'-Dichlorobiphenyl) in Chicago Air. Environ. Sci. Technol [Epub ahead of print] 10.1021/es801823r.
