By Jack Schatz
The Carcinogen Identification Committee (CIC), a scientific expert committee appointed by the Governor, has added TDCPP—also known as chlorinated Tris—to the Proposition 65 list, but declined to list fluoride and its salts at its annual meeting in Sacramento.
The committee voted 5-1 in favor of listing TDCPP, a flame retardant common in furniture and baby products as a carcinogen.
Although TDCPP was banned from children’s pajamas by the U.S. Consumer Product Safety Commission in 1977, it recently experienced a resurgence in furniture foam. Today, it is the nation’s most commonly used flame retardant in furniture and baby products.
“The listing of chlorinated Tris on Prop. 65 is a public health victory,” said Sarah Janssen, senior scientist for the Natural Resources Defense Council. “Widespread exposure to this chemical, now officially identified as a cancer-causing chemical, is a threat to vulnerable populations. This listing should result in labeling requirements for products that contain dangerous levels of this chemical.”
“Flame retardants like Tris leach out of furniture and end up in dust in our homes. We unknowingly inhale and ingest Tris into our bodies,” said Arlene Blum Ph.D., Visiting Scholar at the University of California, Berkeley Chemistry Department and executive director of the Green Science Policy Institute. “We tested 100 baby products and 100 couches, and found dangerous levels of Tris more often than any other flame retardant.”
But Jackson Morrill, director at the American Chemistry Council downplayed the importance of the listing.
“It is important for consumers and manufacturers to understand that today’s decision to include TDCPP on the Proposition 65 list is only one part of a full assessment that California is going to take. The listing of a chemical under Prop 65 does not automatically mean a consumer’s health is threatened or that product manufacturers have to include a product label. In the case of TDCPP, consumer products would be evaluated for potential exposure and would not require a label at all if that exposure poses no significant risk to public health. Californians should be reassured by the most recent and comprehensive assessment on TDCPP and carcinogenicity, completed by the EU in 2008, which concluded that there were no concerns for consumers from potential inhalation or for children via the oral route,” Morrill said in a prepared statement.
Arbamarle Corporation, the principal manufacturer of TDCPP in the U.S., argued that OEHHA had failed to clearly show the flame retardant causes cancer.
Arbamarle’s representatives argued that “TDCPP is differentiated from structurally similar chemicals that are carcinogens by metabolism to structurally distinct, lower toxicity, metabolites.” The body of research demonstrates that TDCPP, in contrast to the other compounds, is very rapidly and nearly completely conjugated prior to further metabolism. The company also argued “it is reasonable to assume that TDCPP is devoid of genotoxic potential” citing a 2010 study by the European Chemical Agency.
In written comments, Arbamarle’s consultant, Arthur Lawyer of Technology Sciences Group, emphasized that epidemiological data on TDCPP is limited and “these data do not provide any evidence that TDCPP causes cancer of any type, including invasive cancer, in humans.” Lawyer’s comments also asserted that none of the tumors found in animal studies supporting the listing were invasive.
However, committee members had a different opinion about character of the tumors found in animal studies, citing studies included in OEHHA’s Hazard Identification Materials and staff presentation which reported malignant, combined malignant and benign liver tumors, benign kidney tumors, testicular interstitial cell tumors in male Sprauge-Dawley rats.
For David Eastman, and several other committee members, the fact that four of TDCPP’s metabolites (1,3-DCP, 3-MCPD, Epichlorohydrin and Glycidol) are already listed under Proposition 65 was most persuasive, eventually causing them to vote in favor of the listing.
“We thank the committee for its careful consideration of the evidence regarding the health effects of Tris,” said Sam Delson, deputy director for external and legislative affairs for OEHHA. “Now that the state’s qualified experts have found that this chemical causes cancer and added it to the Proposition 65 list, a warning requirement will take effect in 12 months.”
The committee also voted on whether to list fluoride, and found there was insufficient evidence to show it is carcinogenic. The committee voted 6-0 in favor of not listing fluoride and its salts as a carcinogen.
Prior to the meeting, OEHHA received dozens of comments from individuals and organizations—both for and against fluoride—regarding its July 2011 report, Evidence on the Carcinogenity of Fluoride and Its Salts.
But after reviewing the scientific evidence, the committee unanimously declined to add fluoride to the Proposition 65 list, saying that the research overall is “inconclusive.”
Among the 60 organizations and individuals who submitted comments to the OEHHA were American Dental Association president Raymond Gist, DDS, and executive director Kathleen O’Loughlin, DMD, MPH.
“Because we believe that the evidence reviewed in the OEHHA report is inconsistent and scientifically inconclusive with respect to drawing conclusions about the potential of fluoride to be carcinogenic in humans, it is important to consider the proven health benefits of fluoride,” they wrote. “Throughout decades of research and more than 65 years of practical experience, fluoridation of public water supplies has been responsible for dramatically improving the public’s oral health.”
Howard Pollick, BDS, MPH, chair of the California Fluoridation Advisory Council, also submitted testimony in support of fluoride.
“The review of the literature in this OEHHA report provides the evidence needed for the Carcinogen Identification Committee to consider whether fluoride and its salts should or should not be among the chemicals listed in Proposition 65,” Pollick wrote. “Additional peer-reviewed evidence since the release of the report provides further evidence that fluoride and its salts should not be listed among the chemicals listed in Proposition 65.”
But some commenters expressed concern over studies that have found a link between fluoride consumption and bone cancer, especially in young males.
“There are numerous studies connecting fluoride with cancer, which are not addressed in the current review document,” stated Kim Glazzard of Organic Sacramento in her written testimony. “The very existence of cumulative fluoride that is stored in the bones and affects the immune system properties which are attributed to bone marrow, and which have a critical role in arresting carcinogenic development, have also not been addressed here.”
David Kennedy, DDS of the San Diego-based Preventive Dental Health Association chastised OEHHA for “15 glaring factual errors,” in its Hazard Identification Materials and then attacked a recently published study that proponents of fluoridation believe shows that there is no link between bone cancer in young men and water fluoridation.
Kennedy first discredited the design of the study, An Assessment of Bone Fluoride and Osteosarcoma, which he contends “presents too small of a subject base for a comparison to the age-sex-related effects presented in the larger Bassin study (NTP, 1989) which found a cancer association.
Kennedy also said the new study, published in the Journal of Dental Research on July 28, did not present adequate controls for a disease that occurs more often in males than females, and asserted that using older patients in the study, is an inappropriate control for bone cancers that occur in younger patients.
The “Kim/Douglass [study] does not, and cannot, disprove the cancer/fluoride link based upon their study design. It is so seriously flawed that it was not even published in a reputable medical journal,” Kennedy wrote.
“A dental journal such as Journal of Dental Research obviously does not have a peer review faculty with an adequate knowledge of epidemiology or normal case controlled research. It is highly inappropriate to publish a complex cancer epidemiological study in a dental journal. The touting of this be-all, end all study even in the previous Proposition 65 considerations accentuates the shortcomings of both the study and its peer review.”
After voting on the proposed listing of Fluoride and its salts, the committee then prioritized 38 chemical candidates for the development of Hazard Identification Materials and consideration at future CIC meetings.