TUESDAY, Sept. 13, 2001 (HealthDayNews) -- If you're a man whose job involves daily exposure to organic solvents such as paints, mineral spirits or inks, your ability to sire children may be at risk.
A new study says men chronically exposed to moderate or high levels of the solvents are more likely to have low sperm counts and less active sperm, both of which are linked to reduced fertility.
Canadian researchers, reporting in the October issue of Occupational and Environmental Medicine, say the risk rises as exposure increases. They says the finding makes a strong argument for reducing on-the-job exposure.
"On the whole, the reproductive system is very well protected, but some substances that can get into the male organs potentially have an effect," says lead study author Dr. Nicola Cherry, director of the Occupational Health Program at the University of Alberta's Department of Public Health Sciences in Edmonton.
Cherry and her colleagues counted sperm and measured sperm motility of 656 men treated at a Montreal fertility clinic from 1972 to 1991. All the men worked in manual trades.
The team also examined the records of 574 similarly employed men who visited 10 other fertility clinics across Canada from 1984 to 1987.
The researchers correlated the men's occupations to a four-level scale of exposure to solvents. They found that men exposed to moderate levels of organic solvents had twice the risk of having a low sperm count and low sperm activity. Men whose jobs involved a high level of exposure, meaning 50 percent above the safe threshold, had triple the risk of low sperm counts and low sperm activity.
Cherry says though scientists don't yet know how, they suspect the compounds affect sperm in the three months during which they are formed from cells lining the testes.
The low sperm counts and low motility levels correspond with World Health Organization levels linked to "a marked effect on fertility," says Cherry. "We can assume that people with these very low levels would have much more difficulty conceiving."
Of 33 men who worked in high-exposure occupations, the most common jobs were printing-press operators and painters. Other high-risk occupations included dry cleaners and workers in marine craft fabrication.
Cherry says exposure to the solvents was primarily via the respiratory system, although roughly 10 percent of exposure occurred through the skin in some occupations.
Though the National Institute for Occupational Safety and Health limits workplace exposure to organic solvents, Cherry says the regulations focus only on the chemicals' effects on the central nervous system.
The researchers suggest that more studies are needed to determine which solvents pose risks to reproductive health. Animal studies have shown that solvents known as glycol ethers, which commonly are found in paints and printing inks, may be particularly hazardous to male fertility.
Dr. Laurence Fuortes, an associate professor of occupational and environmental health at the University of Iowa College of Public Health, says, "We need to stress the need for animal and laboratory toxicology testing of a variety of industry substances." Mixtures of various solvents commonly used also should be tested, he says.
Cherry says the study shows the need for increased vigilance to reduce workplace exposure to all organic solvents, either by switching to less hazardous solvents or by increasing use of safety equipment such as respirators and gloves.
Fuortes says both men and women need to protect themselves from exposure to the solvents. "Mixing and pouring [substances] may be the most hazardous time for unexpected exposure. Hygiene, work practices and minimizing exposure however possible are what need to be stressed," he says.
Cherry is working on a study in the United Kingdom to determine which organic solvents pose the greatest risk to reproductive health.
George Fuchs, the manager of environmental affairs for the National Association of Printing Ink Manufacturers, says he's not aware of any link between the solvents in printing and manufacturing inks and male fertility.
"All chemical manufacturing operations try to minimize exposure [for] the people working with those materials" to comply with Occupational Safety and Health Administration regulations, says Fuchs. "The way they typically do that is through ventilation of the area around the manufacturing equipment to ensure that the levels don't exceed the permissible exposure limit."
"These materials are not handled by hand. These materials are added to the process through an automated means and not manually handled. So in general, that reduces the potential for dermal contact," Fuchs says.
"We as an association have a health safety and environmental effort," says Fuchs. Once any potential effect on fertility has been further studied ,"[we'll] look at the impact of this new toxicity information on our operations," he says.
What To Do
The MFL Occupational Health Center describes organic solvents.
The National Institute of Occupational and Safety and Health has more information about the chemicals. (You'll need Adobe Acrobat to read many of these documents.) And the North Carolina Chemical Injury Network publishes information about other health effects of organic solvent exposure.
