The National Toxicology Program (NTP) declared today that formaldehyde -- a common ingredient in home building products -- causes cancer in humans.
NTP, which is administered by the National Institute of Environmental Health Sciences (NIEHS), listed formaldehyde as "known to be a human carcinogen" in the 12th edition of its "Report on Carcinogens." Formaldehyde had been listed in previous editions as "reasonably anticipated" to cause cancer.
The classification is sure to add to the current debate surrounding formaldehyde and whether it should be more tightly regulated. U.S. EPA has released a draft assessment on the substance that labeled it carcinogenic -- a step toward tougher formaldehyde standards. Aspects of that report, however, were criticized by a National Academy of Sciences review, and industry has launched a significant lobbying effort against new formaldehyde regulations (Greenwire, April 8).
The NTP and NAS reports both agreed with EPA that formaldehyde exposure can lead to cancers of the nose, nasal cavity and upper throat. The NTP report breaks with the NAS review, however, in saying that there is sufficient evidence that formaldehyde exposure causes myeloid leukemia.
NTP acknowledged that there appear to be questions surrounding how formaldehyde affects human cells to produce myeloid leukemia, which was a major reason NAS disagreed with EPA's assessment. However, NTP said there are enough epidemiologic data to justify listing formaldehyde as a cause of the disease.
Formaldehyde is frequently used in adhesives and resins that hold together common furniture, particleboard, cabinets and other products. It is also found in tobacco smoke and automobile exhaust.
NTP is congressionally mandated to produce the "Report on Carcinogens" for the Health and Human Services secretary. The 11th edition of the report was published in 2005.
The formaldehyde finding was applauded by environmental watchdogs who have urged EPA to issue strict regulations on formaldehyde.
"The formaldehyde section is excellent, reflects the current scientific evidence and is consistent with the findings of the National Academies report," said Jennifer Sass, a senior scientist at the Natural Resources Defense Council. "As a public health agency, the NTP made the right decision to describe this risk so that people can make informed decisions about protecting their health."
However, the chemical industry criticized the formaldehyde classification as failing to take into account the NAS, or National Research Council, review.
"We are extremely disappointed that HHS has moved forward with listing formaldehyde in its 12th ['Report on Carcinogens'] as a 'known human carcinogen,'" said Cal Dooley, CEO of the American Chemistry Council. "By doing so, HHS ignored the recently released, independent, peer-review report from the National Research Council, which strongly questioned whether the scientific evidence supports the claim of human carcinogen for leukemia. Also, the World Health Organization indicates that normal human exposures do not present a risk of cancer."
NTP also made it clear that exposure to substances listed in the report does not mean they will cause cancer in everyone. John Bucher, NTP's associate director, noted that the amount of exposure and the individual susceptibility to the chemical determine whether a substance becomes carcinogenic.
Styrene joins list
In addition to formaldehyde, NTP added seven other substances to its report. Most notably, it classified styrene as "reasonably anticipated" to be carcinogenic in humans.
Styrene is commonly used in many rubbers and plastics, including food containers. It is also used to make polystyrene, a common ingredient in foam coffee cups and other food packaging.
Bucher said that the report does not list polystyrene but noted that very small amounts of styrene may leach from polystyrene containers. However, the report, Bucher said, focuses on industrial exposures to styrene, which would be much higher.
Styrene has also become a political issue on Capitol Hill. House Republicans replaced cafeteria food containers with ones containing polystyrene when they won the majority last year, drawing rebukes from Democrats (E&ENews PM, March 8).
The styrene industry criticized the report, noting that it did not take into account that E.U. regulators have said the substance does not represent a human cancer concern.
The Styrene Information and Research Center, representing the industry, said it will "contest vigorously" the NTP classification.
"The designation is completely unjustified by the latest science and resulted from a flawed process that focuses on only those data that support a cancer concern, and in the case of styrene ignored the preponderance of data that fail to suggest a cancer concern for this substance," the group said in a statement.
Other new additions to the report included aristolochic acids, a group of chemicals that are naturally produced in plants that grow in the United States and worldwide. The acids were deemed known to be carcinogenic.
The remaining five additions were all classified as "reasonably anticipated" to cause cancer. They include captafol, a banned fungicide; cobalt-tungsten carbide, which is used in hard metal production and cutting tools; ortho-Nitrotoluene, a component of azo dyes and other agricultural chemicals; riddelliine, which is found in some plants; and some inhalable glass wool fibers.