A common air pollutant previously associated with cancer in adults may also be putting children at an increase risk for chromosomal aberrations (CAs) that may be linked to leukemia and other serious health risks, a new study says.
Researchers from the Columbia Center for Children's Environmental Health (CCCEH) at Columbia University’s Mailman School of Public Health, the Columbia University Medical Center, and the Centers for Disease Control and Prevention (CDC) found naphthalene, the primary component of household mothball fumes, can potentially “scramble” genetic chromosomal coding of children exposed to high levels of the chemical before birth.
Naphthalene is a strong-smelling, white chemical compound commonly found in outdoor and indoor air pollution, including automotive exhaust, tobacco smoke, coal or wood burning stoves, paint, toilet bowl cleaners, PVC plastics and mothballs, among other sources.
The chemical belongs to a class of air pollutants called polycyclic aromatic hydrocarbons (PAH) and is classified as a “possible human carcinogen” by the International Agency for Cancer Research and the U.S. Environmental Protection Agency (EPA).
Studies show naphthalene, a chemical that is virtually everywhere, is associated with hemolytic anemia, kidney and liver damage, and neurological damage, as well as cataracts and retina damage in adults who’ve inhaled fumes, ingested it or have had skin contact with the compound.
Prior research has also established a link between prenatal exposure to PAHs and increased risk for childhood obesity, IQ deficits, and CAs.
The new study is the first to present evidence in humans of CAs, including translocations, associated with exposure to naphthalene during childhood. Chromosomal translocations are a potentially more harmful and long-lasting subtype of CAs.
CAs have been associated with increased cancer risk in adults, says the study’s lead author, Manuela A. Orjuela, MD, an assistant professor of clinical environmental health science at Columbia University Medical Center and whose practice includes child cancer patients at New York-Presbyterian Morgan Stanley Children's Hospital.
“Translocations can persist for years after exposure. Some accumulated damage will be repaired, but not everyone's repair capacity is the same. Previous studies have suggested that chromosomal breaks can double an adult's lifetime risk for cancer, though implications for children are unknown,” Dr. Orjuela says.
Translocations are of special concern as they result in a portion of one chromosome being juxtaposed to a portion of another chromosome, potentially scrambling the genetic script, she said.
For the study, researchers followed 113 five-year-old New York City children to assess just how much naphthalene exposure they were getting by measuring the participants metabolite levels in urine and blood tests. Metabolites are products of the body's metabolism, and can serve as markers for the presence of a chemical in the human body.
CAs were present in 30 children. Of these, 11 had translocations. With every doubling of levels of the chemical in urine and blood cells, translocations were 1.55 and 1.92 times more likely, respectively, to occur.
To obtain a better sense of the long-term consequences of naphthalene exposure, Dr. Orjuela and other CCCEH investigators are following some of the children in the study as they reach fourth grade. While they expect to see further translocations, they do not expect to see any signs of cancer in the white blood cells.
"So far, the translocations seem to be random, and there has been no evidence of the specific translocations known to be associated with leukemia. This is entirely expected; leukemia is very rare," says Dr. Frederica Perera, director of Columbia Center for Children's Environmental Health and senior author on the paper.
“However, the findings provide yet more evidence of the vulnerability of the young child to carcinogenic air pollutants.”
The research is published in early online edition of Cancer, Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research and was supported by the National Institutes of Health, The U.S. EPA and the New York Community Trust.
Lynette Summerill is an award-winning writer and Scuba enthusiast living in San Diego, CA with her husband and two beach loving dogs. In addition to writing about cancer-related issues for EmpowHER, her work has been seen in newspapers and magazines around the world.
Sources and Consumer information:
“Naphthalene Information. U.S. EPA Technology Transfer Network Air Toxic Web site. Accessed May 29, 2012 at: http://www.epa.gov/ttn/atw/hlthef/naphthal.html
Health Child Healthy World. Chemical Encyclopedia: Naphthalene. Accessed May 29, 2012 at:
http://www.healthychild.org/issues/chemical-pop/naphthalene
“Urinary napthol metabolites and chromosomal aberrations in 5 yr old children.” Manuela Orjuela, Xinhua Liu, Rachel L. Miller, et al. Cancer Epidemiology Biomarkers and Prevention, published OnlineFirst on May 9, 2012; DOI:10.1158/1055-9965.EPI-12-0214. Abstract at: http://cebp.aacrjournals.org/content/early/2012/05/08/1055-9965.EPI-12-0214.abstract/ news release at: http://www.eurekalert.org/pub_releases/2012-05/cums-cet052912.php
Reviewed May 31, 2012
by Michele Blacksberg RN
Edited by Jody Smith