Time may not reduce brain effects of solvent exposure

By Shereen Jegtvig NEW YORK (Reuters Health) - Workers exposed to solvents on the job may experience memory and thinking problems decades later, according to a new study. Exposure to paints, degreasers, adhesives and glues is common in some occupations, and has been linked to problems such as memory loss, reduced cognitive processing speed and difficulty staying focused. “We do know that in the short term, certain chemicals at work – solvents – are known to affect cognitive health, but there isn’t a lot done that has looked at the long-term impact on cognitive function, particularly after people retire,” said Erika Sabbath, of the Harvard School of Public Health in Boston, who led the study. Problems at older ages, things like memory, reasoning or task-switching are very common, and we know surprisingly little about what causes them or how to prevent them, she told Reuters Health. Generally, this is the same period of life when people begin to experience cognitive decline, she added, so she and her colleagues wanted to see if there were certain patterns of lifetime exposure to solvents that predicted cognitive problems after retirement. “When we looked at those where the exposure happened a long time ago, 30 to 50 years before, we found that the effects of solvents on cognitive function didn’t necessarily fade away,” she said. The study also found that people who had the most exposure to solvents and were also exposed most recently had cognitive problems in areas classically associated with solvent exposure, but also other areas of cognitive function. The findings were published in Neurology. The researchers used information from the GAZEL cohort – a large study made up of workers with the French national utility company – that began in 1989. They analyzed data on 2,143 male retirees, but did not include women because they were generally not exposed to high levels of solvents. Using company records, they assessed the workers’ lifetime exposure to fumes from chlorinated solvents, petroleum solvents, benzene and non-benzene aromatic solvents. The participants were categorized as having no exposure, moderate exposure if they had less than the average amount and high exposure if they had greater than the average amount of solvent exposure. The research team also divided the participants according to whether they were exposed 12 to 30 years prior to the cognitive testing – the “recent exposure” group – or 31 to 50 years earlier, the “distant exposure” group. Overall, 26 percent of the men were exposed to benzene, 33 percent to chlorinated solvents and 25 percent to petroleum solvents. When they were about 10 years into retirement, at an average age of 66 years old, they took eight tests that measured their memory and thinking. A total of 59 percent of the participants had impairment on between one and three of the eight tests, 23 percent had impairment on four or more tests and 18 percent had no impaired scores. The research found that retirees with high, recent exposure were at greatest risk for memory and thinking deficits, but the risk still remained somewhat elevated for those who were exposed more than 30 years before testing. The findings didn’t change when the researchers took education, age, smoking and alcohol consumption into account. Sabbath explained that her study didn’t look at exact dosage of solvent exposure, but previous studies indicate that solvents can have a negative impact on health at legal limits. The Occupational Safety and Health Administration, or OSHA, sets U.S. standards on how solvents should be handled in the workplace and what levels of exposure are safe. Sabbath cautioned that only a person who is certified in industrial hygiene can give detailed advice for workers currently exposed to specific solvents on how to protect themselves, but she offered some tips. “In general using a respirator, ventilating the area and if possible eliminating the exposure altogether, for example, people who use paints to switch to versions that have no or lower levels of VOCS, the volatile organic compounds,” she said. SOURCE: http://bit.ly/1o7alFR Neurology, online May 12, 2014.