Glycol solvents seem to be key
Men regularly exposed to chemicals found in paint may be more prone to fertility problems, research suggests.
Men such as painters and decorators, who work with glycol solvents, are two-and-a-half times more likely to produce fewer "normal" sperm.
The UK study looked at more than 2,000 men attending 14 fertility clinics.
However, the Occupational and Environment Medicine study found a wide range of other chemicals had no impact on fertility.
Sperm motility - the amount of movement of individual sperm - is an important factor in overall fertility.
There had been fears that exposure to a wide variety of workplace chemicals might affect a man's ability to father a child.
The joint research project between the Universities of Manchester and Sheffield looked at two groups of men attending fertility clinics - those with sperm motility problems, and those without them.
The men were questioned about their jobs, lifestyles, and potential exposure to chemicals, revealing a 250% increase in risk of sperm motility problems among those exposed to glycol ethers.
These chemicals are widely used as solvents in water-based paints.
This risk was present even after other lifestyle factors, such as smoking, wearing tight underpants, testicular surgery and manual work, were taken into consideration.
Dr Andy Povey, from the University of Manchester, said: "We know that certain glycol ethers can affect male fertility and the use of these has reduced over the past two decades.
"However, our work suggests they are still a workplace hazard and further work is needed to reduce such exposure."
However, this was the only chemical linked to fertility problems in men, and Dr Allan Pacey, a fertility specialist from Sheffield University, said that this would ease men's worries.
"Infertile men are often concerned about whether chemicals they are exposed to in the workplace are harming their fertility.
"Therefore it is reassuring to know that on the whole, the risk seems to be quite low."