Long Term Cognitive Problems on Exposure to Paint, Glue, Degreasers

A new study highlights a strong association between exposure to workplace solvents and cognitive problems, decades after the exposure.

On a daily basis nearly millions of workers are exposed to solvents such as paints, glue and degreasers. This exposure either in the form of vapor, mist or liquid is known to take a toll on human health. A latest study conducted on a group of retirees from a French power company found that people exposed to solvents and benzene in their work environment, decades earlier, were more vulnerable to suffer from memory and thinking problems.

For this study, researchers at the Harvard School of Public Health, Boston, examined over 2,143 retirees from the French National Utility Company.  The finding was based on the analysis conducted on the worker's lifetime exposure to various solvents that included chlorinated solvents, petroleum solvents and benzene.  They also looked at the timing of the last exposure and lifetime dosage.

"Our findings are particularly important because exposure to solvents is very common, even in industrialized countries like the United States." study author Erika L. Sabbath, ScD, of Harvard School of Public Health in Boston, said in a statement. "Solvents pose a real risk to the present and future cognitive health of workers, and as retirement ages go up, the length of time that people are exposed is going up, too."

Benzene, an organic chemical compound, is mostly used in making plastics, rubber, dye, detergents and other synthetic materials.  On the other hand, chlorinated solvents are used in dry cleaning solutions, engine cleaners, paint removers and degreasers.  What is found in carpet glue, furniture polishes, paint, paint thinner and varnish is  petroleum solvents. 

Of the 2,143 retirees, nearly 26 percent were exposed to benzene, 33 percent had exposure to chlorinated solvents and 25 percent were exposed to petroleum solvents.

As a part of the study, the subjects were made to undertake 8 tests that helped evaluate their memory and thinking skills.  The tests were taken on an average of 10 years after retirement when the average age was 66. The researchers noticed that 59 percent of them had impairment on 1-3 of the 8 tests, 23 percent of them were seen having impairment in four or more tests and 18 percent of them had no impaired scores.

After taking into consideration the historical company records, the researchers determined the average lifetime solvent exposure.  The participants were categorized as having no exposure, moderate exposure on having average exposure and high exposure if it was higher than average.

Further, the participants were divided by the time of last exposure. Recent exposure was from 12-30 years before the test and distant exposure if it was 31-0 years prior to the tests.

The researchers noticed that those with high, recent exposure to solvents suffered a greater risk of memory and thinking problems.

"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," Sabbath said. "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."

The only way the workers can receive benefit is from regular cognitive screening to detect problem early. 

The finding was documented in the American Academy of Neurology.