(Beyond Pesticides, January 5, 2009) According to a new study published December 2008 in the online edition of Environmental Health Perspectives, hexavalent chromium (or chromium VI) found in the wood preservatives chromated copper arsenate (CCA) and acid copper chromate (ACC), is a human carcinogen following chronic oral exposure. Previous studies have shown that hexavalent chromium compounds can increase the risk of lung cancer via inhalation exposure. Chromium VI is the notorious chemical that caused cancer in the residents of Hinkley, CA and brought to light by the work of Erin Brockovich.
The National Toxicology Program (NTP) conducted 2-year drinking water studies of chromium VI (as sodium dichromate dihydrate) in male and female F344/N rats and B6C3F1 mice. Exposure resulted in increased incidences of rare neoplasms of the squamous epithelium that lines the oral cavity (oral mucosa and tongue) in male and female rats, and of the epithelium lining the small intestine in male and female mice. The authors determined that chromium Vi is carcinogenic following administration in drinking water to male and female rats and mice.
The International Agency for Research on Cancer (IARC), the U.S. Department of Health and Human Services, and the Environmental Protection Agency (EPA) each have previously determined that hexavalent chromium is a known human carcinogen.
The Agency for Toxic Substances and Disease Registry reports that breathing high levels of hexavalent chromium can cause irritation to the nose, resulting in runny nose, nosebleeds, and ulcers and holes in the nasal septum. Ingesting large amounts of hexavalent chromium can cause stomach upsets and ulcers, convulsions, kidney and liver damage, and even death. Skin contact with certain hexavalent chromium compounds can cause skin ulcers. Allergic reactions consisting of severe redness and swelling of the skin have been noted.
Chromium VI is still used as an ingredient in wood preservatives. Although, as of January 2004, most residential uses of CCA can no longer be manufactured for decks and patios, picnic tables, playground equipment, walkways/boardwalks, landscaping timbers, or fencing- already existing residential CCA-treated wood and structures may continue to be sold and used. Industrial uses, such as utility poles, continue to be manufactured and put workers and the public at risk.
Beyond Pesticides has called for a banning of these heavy duty wood preservatives and said that the voluntary phase-out of residential uses of these chemicals does not adequately protect public health or the environment. Occupational exposures increase the risk of cancers in workers. These chemicals also impact the environment and have been found in surface waters. In fact, the major source of contamination in surface waters and groundwater is wastewater from wood preserving facilities. Individuals living or working near wood preserving facilities are exceptionally susceptible to being exposed to surface water or groundwater, increasing their exposure and risk. These preservatives are also known to leach from previously treated wood. Children are also at risk if they put their unwashed hands in their mouths after touching soil or wood that is contaminated with these preservatives. As a result, public and environmental health continues to be compromised.
In April 2008 the U.S. Environmental Protection Agency (EPA) released for public comment its revised risk assessments for three heavy-duty toxic chemical wood preservatives. Read Beyond Pesticides comments.