Environmental Factor, March 2010, National Institute of Environmental Health Sciences
Superfund Research Prompts Review of Antimicrobials
By Jessica Barnwell
A call for more stringent regulations for antimicrobial compounds by Rep. Edward Markey (D-Mass) could mean that the days of antibacterial trash bags are numbered. Markey's petition (http://markey.house.gov/index.php?option=com_content&task=view&id=3823&Itemid=181) to the U.S. Environmental Protection Agency (EPA) in January was based in part on Superfund Research Program (SRP) findings by grantee (http://tools.niehs.nih.gov/srp/people/details.cfm?Person_ID=15130) Rolf Halden, Ph.D. Halden's research on the synthetic biocides triclosan (TCS) and triclocarban (TCC), demonstrated the chemicals' environmental persistence and bioaccumulation in aquatic species.
In response to a request from Rep. Markey, who is chairman of the Energy and Environment Subcommittee of the Energy and Commerce Committee, Halden provided a synopsis of the state of the science as background information. Halden (http://www.biodesign.asu.edu/labs/halden/) is an associate professor in the School of Sustainable Engineering and the Built Environment at Arizona State University (ASU) and author of several studies on the compounds, including a 2005 analysis (http://www.ncbi.nlm.nih.gov/pubmed/15819193?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=4) cited by Markey in his letter and a 2009 review (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684649/?tool=pubmed).
Confronting health concerns about biocide exposures
Triclosan is found in soaps, deodorants, toothpastes, shaving creams, mouth washes and cleaning supplies, and it is infused into an increasing number of consumer products, such as kitchen utensils, toys, bedding, socks, and trash bags. Triclocarban is used most widely in soaps and detergents. However, the safety of both antimicrobials has been questioned in regard to environmental and human health. While the companies that manufacture products containing these chemicals claim them to be safe, according to its fact sheet on triclosan (http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm), the EPA is taking a closer look at the two chemicals, which are registered as pesticides with the agency.
Concerns are driven in part by the molecular structures of both compounds, which resemble other persistent toxic chemicals, such as dioxins and PCBs. Indeed, technical grade triclosan contains trace amounts of toxic dioxins as manufacturing impurities and can be converted by heat and irradiation to form additional dioxins.
In histo EPA Administrator Lisa Jackson on Jan. 5, Markey indicated there may be a "strong basis" for triclosan chemicals to be tested in EPA's endocrine disruptor screening program and regulated under the Safe Drinking Water Act (SDWA).
The EPA recognizes the growing body of data regarding triclosan and other persistent antimicrobial agents. In its fact sheet on triclosan, the agency said it intends to begin its next review of triclosan's registration in 2013, ten years earlier than originally planned.
SRP support for additional research
In addition to Halden's work at ASUxtensive environmental monitoring and endocrine disruption work on triclosan and triclocarban has also been conducted with SRP support (http://tools.niehs.nih.gov/srp/people/details.cfm?Person_ID=4201) in the laboratory of Bruce Hammock, Ph.D. (http://www.biopestlab.ucdavis.edu/), at the University of California - Davis (UCD). The UC Davis team provided evidence for endocrine disrupting effects of TCC and TCS. In addition to their respective parent project involvement with TCC and TCS, the ASU and UCD groups are collaborating on an SRP American Recovery and Reinvestment Act-funded supplement to study TCC toxicity in animals and humans, as well as to determine the TCC body burden in the general US population.
(Jessica Barnwell is a communication specialist with MDB, Inc., a contractor for the NIEHS Superfund Research Program and Worker Education and Training Program.)