Why the ads? We don't charge a membership fee for our site. So, please enjoy our research reviews, request additional topics, and consider browsing through the links and take advantage of the special offers to make our research efforts possible. Thank You! Vielen Dank! Merci! Arigatou gozaimasu! Kiitos!

Search Research Bench


Wednesday, July 27, 2011

2011: Did Exposure to PCBs Cause Thyroid Disease?

New research reports on the possible link between thyroid disease and PCBs

By Melanie Hundley

If you were a tot in the 1960s in the U.S., your frame of reference for PCB (polychlorinated biphenyl) chemicals may have been similar to mine.  PCBs were around, but you were unaware of them. You probably did not hear about the cattle feed disaster in Michigan in 1973-74. At best, about 1980, your parents may have pointed to the big gray cylinders mounted on telephone poles (transformer pots) and told you to "never touch one of those if you find it on the ground."


Eventually more people did hear about the health hazards of PCBs, but news moved slowly in those olden days.  We had no ubiquitous Internet, limited news sources, and no online MSDS sheets to share that type of information. 


Reference searches advise that PCBs were in the chemical literature as far back as 1881 and commercialized about the time of the U.S. Great Depression.  The U.S. Environmental Protection Agency was hot on the PCB trail by 1979, and various state environmental studies such as those in Wisconsin and Michigan have since raised awareness about environmental PCB-type contamination and risks.


PCBs et al are still the topic of CDC reports, public notices, and academic journals owing to their environmental persistence and seemingly elusive causal epidemiology.  The Agency for Toxic Substances and Disease Registry (ATSDR) advisory expands beyond the electrical grid, "Children should be told that they should not play with old appliances, electrical equipment, or transformers, since they may contain PCBs."


According to the 2006 amendments to the Codex Alimentarius, which I call the "world's food safety code," there are documented recommendations and warnings shared worldwide on preventing PCB contamination in the global food chain.


New Report Published
Researchers from Georgia and Michigan recently collaborated to assess the odds of tying thyroid disease to PCB exposure and another similar chemical, polybrominated biphenyl (PBB).  In the upcoming August 2011 issue of Chemosphere, Yard et al analyzed data from the Michigan Long-Term PBB study which had taken blood serum concentrations of the participants for both PBB and PCB at the time of their exposure. 


Reviewer notes that the August report appears to treat PBB and PCB exposure interchangeably, and the results appear generalized for these similar halogen-related chemicals.


Yard et al's report details the "materials and methods" of their scientific review.  Elaborating on their methods of down selection from the original population of participants, they reported focusing on a cohort or group with these attributes:
  • 1525 women were eligible to be included here from the larger group;
  • The average age of their exposure to PBB was 25;
  • They were "monitored" an average of 23 years after their reported exposure; and
  • Early blood levels for one of the PBB chemicals averaged about 15.0 parts per billion.
Results
Yard and team said their study supported earlier findings that women apparently have a much higher incidence of thyroid disease than men. However, they also report that based on their study, "thyroid disease incidence is not related to serum PBB or PCB concentrations."


Commonly disclosed in academic research, they shared that their research was supported by government grants. Yard et al suggested that future studies could be conducted using the Michigan Long-Term PBB data to look at the incidence of thyroid disease in the offspring.  This research appears to offer some positive news for the Michigan PCB and cattle feed saga and likely will be interpreted to address some aspects of PCB [and PBB] concerns in general.


A special thanks to Dr. Michele Marcus, Professor of Epidemiology, Rollins School of Public Health, Emory University, for providing extra insight on their research to support this review.

Disclaimer: This is an editorial review only, written by a non-medical author, and subject to change or update.  The information and links contained in this article are for educational purposes only to support further inquiry and should not be used for diagnosis or to guide treatment. Any reader who is concerned about his or her health should contact a licensed medical doctor for advice.  While every effort is made to ensure accuracy, readers should always refer to the original cited sources for verification and/or any interpretation of source material. Author assumes no liability for content, errors, and/or omissions.

Sources
  • 3E Company. (2011). MSDS Solution Center.  Retrieved July 27, 2011, from corporate website.
  • Abbasian, J., Lindahl, H. (2006). Design of Novel Mobile Process for Remediating PCB Contaminated Soils. Illinois Institute of Technology.  Retrieved July 27, 2011, from education website.
  • Agency For Toxic Substances and Disease Registry & U.S. Department of Health and Human Services (2004). Polybrominated Biphenyls. Retrieved July 27, 2011, from government website.
  • Agency For Toxic Substances and Disease Registry & Centers For Disease Control and Prevention. (2011, March 3). Public Health Statement for Polychlorinated Biphenyls. Retrieved July 27, 2011, from government website.
  • Brain, Marshall.  (2000, April 1). How Power Grids Work. Retrieved July 27, 2011, from HowStuffWorks corporate website.
  • Centers for Disease Control & Prevention. (2011, February 28). National Report on Human Exposure to Environmental Chemicals: Serum 2,2',4,4',5,5'-Hexachlorobiphenyl (PCB 153). Retrieved July 27, 2011, from government website.
  • Cornell University. (1993, September). Epidemiology. Retrieved July 27, 2011, from education website.
  • MedicineNet, Inc. (2004, January 18). Definition of PCBs. Retrieved July 27, 2011, from MedicineNet online database.
  • Michigan Department of Community Health. PBBs (Polybrominated Biphenyls) in Michigan. Retrieved July 27, 2011, from government website.
  • Terrell, M. et al. (2009). A cohort study of the association between secondary sex ratio and parental exposure to polybrominated biphenyl (PBB) and polychlorinated biphenyl (PCB). Environmental Health, Vol 8:35. Retrieved July 27, 2011, from PubMed government online database.  PMID: 19682390. 
  • Farlex. (2007). Halogen.  The American Heritage® Medical Dictionary. Retrieved July 27, 2011, from corporate website.
  • United States Environmental Protection Agency. (2011, June 8). Press Release: EPA Bans PCB Manufacture; Phases Out Uses. Retrieved July 27, 2011, from government website.
  • World Health Organization and Food and Agriculture Organization. (2006). Code of Practice for the Prevention and Reduction of Dioxin and Dioxin-like PCB Contamination in Food and Feeds. Retrieved July 27, 2011, from organization website. Reference CAC/RCP 62.
  • World Health Organization and Food and Agriculture Organization. (2011). CODEX alimentarius. Retrieved July 27, 2011, from organization website.
  • Wisconsin Department of Natural Resources. (2008, October). PCBs in the Fox River. Retrieved July 27, 2011, from government website.
  • Yard, E. E., Terrell, M. L., Hunt, D., Cameron, L. L., Small, C. M., McGeehin, M. A., & Marcus, M. (2011). Incidence of thyroid disease following exposure to polybrominated biphenyls and polychlorinated biphenyls, Michigan, 1974–2006. Chemosphere, 84(7), 863-868. doi:10.1016/j.chemosphere.2011.06.020
Article Copyright 2011 by Melanie Hundley, U.S.A.  All Rights Reserved. No claim is made to other copyright materials cited. 
Photo credit: graur razvan ionut.

For more information, consider:
Levels and vertical distribution of PCBs in agricultural and natural soils from Sweden [An article from: Science of the Total Environment, The]The Merck Index: An Encyclopedia of Chemicals, Drugs, and BiologicalsBiocidal: Confronting the Poisonous Legacy of PCBsLiving Downstream: A Scientist's Personal Investigation of Cancer and the Environment

No comments: