By Jessica Firger
Over several decades, scientists and health experts have identified links between industrial cleaning chemicals and increased risks for certain cancers. In particular, the chemical tricholoroethylene (TCE) -- a solvent typically used for cleaning and degreasing metals and as a commercial dry cleaning agent -- has been found to cause several types of cancers, including cancer of the kidney, cervix, and esophagus, as well as non-Hodgkin lymphoma. TCE has also been linked to increased risk for Parkinson's disease.
A new paper, published in the Journal of the National Cancer Institute, adds to the growing body of evidence, identifying a strong connection between TCE and increased liver cancer risk.
The observational study analyzed cancer registries from Finland, Sweden, and Denmark that included a total of 5,553 workers with documented exposure to TCE. Researchers looked at records of urine tests documented in the databases in the years 1947 to 1989.
They found that workers with significant exposure to TCE had a two-fold increase in risk for developing liver cancer. "The liver metabolizes this chemical," explained Johnni Hansen, PhD, of the Danish Cancer Society Research Center in Copenhagen and lead author of the study. "All the blood needs to go through the liver. This was also seen in the animal experiments."
Though Dr. Hansen said the rates of other types of cancers among the surveyed workers were not statistically significant, he suspects this will change over time. "We're already seeing an increased risk for cervical cancer but we need to follow up with them for the next few years," he said. He added that because the information in the registries was limited, he and his team were unable to account for the influence of lifestyle factors such as alcohol and tobacco use in the development of liver cancer.
A Long History of Worker Exposure to TCE
TCE has been used widely over the last century in a variety of manual labor jobs -- from printers and resin workers to shoemakers and textile cleaners. According to the Agency for Toxic Substances & Disease Registry, a division of the U.S. Centers for Disease Control, the majority of TCE manufactured in the United States is used for hard labor jobs, such as removing paint from metals.
"This study provides further evidence that TCE exposure was associated with liver cancer," said Mark Purdue, PhD, from the division of cancer epidemiology and genetics at the National Cancer Institute, who wrote the accompanying op-ed. "It provides added evidence that we need to be concerned about the potential effects of TCE."
Purdue said a number of health organizations have, over the years, petitioned for stricter regulations on TCE. Last fall, he said, the International Agency for the Research on Cancer, an arm of the World Health Organization, held an expert panel to review the research and evidence on the dangers of TCE. The testimony they heard led the organization to upgrade the chemical to group 1 agent status, meaning it's a known carcinogen, from group 2 agent status -- thus flagging the chemical as highly toxic.
The Dry-Cleaning Connection
Hansen said TCE is also present in trace levels in some tap water, and is used in several consumer products such as home upholstery cleaners, adhesives, and paint strippers. But he said in such instances, a person's exposure to the chemical is limited, and therefore cancer risk is probably low.
Though popular as a dry-cleaning solvent in the mid-century, TCE is less commonly used in the dry cleaning industry now. Nora Nealis, executive director of the National Cleaners Association, said dry cleaners typically use perchloroethylene, another solvent that's also been flagged by health agencies for its potentially toxic effects. The National Institutes of Health has reported that perchloroethylene caused tumors in two rodent species.
Nealis said such ongoing research into chemical solvents has prompted scores of dry-cleaning shop owners to phase out perchloroethylene and replace the popular cleaning agent with products made from compounds similar to those used in the cosmetic industry, which have been found to be less toxic.
"Since dry cleaning is pretty much a family business, they err on the cautionary side," said Nealis, who has worked in the industry for more than three decades."They make the most informed and wisest decisions they can."
"Cleaning Solvent Tied to Cancer Risk" originally appeared on Everyday Health.