In the first long term look at how solvents affect the brain, researchers say some chemicals are linked to cognitive problems 30 years after exposure
We’re exposed to solvents all the time – they’re used in detergents, dry cleaning, paint, glue and furniture polishes – but how are they affecting our health? Most studies focus on relatively short term effects – a few years or so.
So Erika Sabbath, a research fellow at the Harvard School of Public Health and her colleagues decided to take the long view. Taking advantage of data from France, they analyzed solvent exposure among retired electric utility workers at the national company, many of whom started working in their 20s. They correlated that information with results from a series of eight memory and thinking tests that the workers took on average 10 years after they retired.
“What was really surprising was that some people, whose last exposure was 30 year to 50 years before the assessment, were still exhibiting some cognitive difficulties after they had retired,” says Sabbath. “[Other] studies haven’t shown effects that persist this long.”
The team wasn’t able to pinpoint a specific level of danger that distinguished those with more cognitive problems from those with fewer. But they did find a strong pattern linking higher exposure, even decades prior, to worse outcomes on tests of memory, attention and processing speed compared to those with no or less exposure.
Even more concerning, says Sabbath is that her analysis found the first hints of deficits in brain functions that previous studies didn’t identify. Retirees with the highest and most recent level of exposure – in the last 12-30 years – had trouble remembering words they had heard verbally, and in retrieving information such as recalling as many animals as they could in a minute. “These people had cognitive problems even in areas that aren’t classically associated with solvents,” she says. “There was a spillover effect into other domains.”
The solvents measured in the study included chlorinated and petroleum solvents as well as benzene, all of which are used in plastics, rubbers, dyes and compounds like degreasers and paints.
Could the same long term effects be found in people who aren’t exposed in the same way that the utility workers were? The exposures in the study were lower than levels that the French and U.S. governments set for harm, but as the findings show, researchers are only just beginning to analyze, and understand how cumulative and long term the potentially dangerous effects of these chemicals may be. Sabbath hopes that the results alert regulatory agencies to the potential long term damage that solvents can have, but realizes that those changes are challenging to make. “The best possible outcome is that permissible exposure levels are reviewed,” she says. “But given the difficulty in changing regulations, especially with the gridlock in Washington, that could be a long term goal.”
In the meantime, how real is the risk for others who may work with solvents but not at the same level as utility workers? Are people who work at dry cleaners facing similar risk of years of brain damage? Or those who work at nail salons? Are painters at risk too? Because the study did not calculate doses of exposure, Sabbath says those questions can’t be answered yet. But there are ways that those concerned about solvents can modify their risk – by protecting themselves with masks and by making sure that they are in well-ventilated areas, as well as switching to products like paints and cleaners that don’t contain volatile organic compounds. “If it were my family member, I would encourage them to protect themselves based on this evidence,” she says.