Cognitive Costs of Chemical Exposure

Impaired memory skills showed in retirees no longer handling potentially dangerous everyday solvents

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Certain laundry detergents, wall paints, patio furniture varnishes and other products for indoor and outdoor home upkeep leach sometimes dangerous fumes. Those fumes’ negative health effects may be lasting.

Even after they had retired, former workers at a French electricity company had memory loss and other cognitive symptoms of exposure to chemical solvents they had used on the job, according to a new study.

For some retirees, their exposure ended as much as 50 years ago.

Many of those workplace chemicals are commonly used in homes, whether as degreasers or for sprucing things up.

"Find out if there are harmful chemicals in your home."

The study’s lead author was Erika L. Sabbath, ScD, of Harvard School of Public Health’s Center for Population and Development Studies in Boston.

The subjects of this study by Dr. Sabbath and colleagues included 2,143 retirees from Electricite de France, a government-owned utility company.

Using records from that utility, these researchers calculated the duration and dosage of those retirees' workplace exposure to benzene, chlorinated solvents and petroleum solvents.

Certain plastics, rubber, dye, detergents and other synthetic materials contain benzene. Chlorinated solvents are found in, among other substances, dry cleaning solutions, engine cleaners, paint removers and degreasers. Petroleum solvents are used in carpet glue, furniture polishes, paint, paint thinner and varnish, these researchers wrote.

The study participants were enrolled in Gazel, a health research project tracking 20,000 French utility workers. Of the 20,000, 15,000 Gazel enrollees were men.

Of the 2,143 chemical study participants, 26 percent had been exposed to benzene, 33 percent to chlorinated solvents and 25 percent to petroleum solvents.

In 2010, roughly 10 years after participants retired and when they were, on average, 66 years old, they were put through eight standardized tests of their memory and thinking skills. Those results showed that, on one to three of those tests, 59 percent of study participants showed signs of impaired memory and thinking. On four or more tests, 23 percent participants showed impairment. No impairments were evident in 18 percent of the study participants.

“The people with high exposure within the last 12 to 30 years showed impairment in almost all areas of memory and thinking, including those not usually associated with solvent exposure,” Dr. Sabbath said in a press statement.

She continued, “But what was really striking was that we also saw some cognitive problems in those who had been highly exposed much longer ago, up to 50 years before testing. This suggests that time may not fully lessen the effect of solvent exposure on some memory and cognitive skills when lifetime exposure is high.”

As one example, those with recent exposures to chlorinated solvents were 65 percent more likely than those without recent exposures to those solvents to have test scores reflecting impairments in their ability to remember, to switch between different everyday tasks requiring them to think or to sufficiently recall an image they had seen.

"These findings underscore the importance of testing older individuals and retirees to understand whether [memory] deterioration happens differentially for those with and without solvent exposures," the researchers wrote.

“Of course, the first goal is protecting the cognitive health of individual workers," Dr. Sabbath added. "But protecting workers from exposure could also benefit organizations, payers and society by reducing workers’ post-retirement health care costs and enabling them to work longer. That said, retired workers who have had prolonged exposure to solvents during their career may benefit from regular cognitive screening to catch problems early."

This study was published online May 12 in Neurology.

The French National Research Agency and French Agency for Sanitary Security of Environment Work funded this study. The authors reported that those government agencies had no say in study design, data collection analysis or development of the final report.

Several of the researchers had gotten research grants from the French National Research Agency and, in the United States, the National Institutes of Health.

Review Date: 
May 9, 2014
Last Updated:
May 13, 2014