Solvents commonly used at work and in the home can cause serious long- term neurological damage when inhaled or brought into contact with the skin. Studies show that people exposed to the chemicals have suffered symptoms ranging from tingling and numbness to muscle weakness and loss of feeling.
In more advanced cases, when the brain is affected, the symptoms may mimic those of multiple sclerosis or dementia, with loss of memory, inability to think clearly and depression. One high-dose exposure or low- level exposure over a long period can be enough to cause damage.
Professor Roberta White and Dr Susan Proctor, environmental health experts at the University of Boston, in Massachusetts, say in the Lancet that almost 10 million people in the United States have daily contact with solvents and the number is rising with increasing use of the chemicals in new technologies. Workers in solvent-using industries, such as paint production, car manufacture and dry-cleaning are at greatest risk of nerve damage, but people using paints and glues at home may also be at risk, they say.
Many of those affected recover spontaneously as soon as they stop using the chemicals but for others in whom symptoms persist, treatments are limited.
Patients whose moods have been affected may be helped by therapy and anti-depressant drugs.
The authors say prevention is essential by ensuring levels of solvents in the air are kept low and that workers wear masks.
They cite the case of a 50-year-old glazier who had spent his professional life working with solvents but never used a respirator and had only worn gloves for two years.
He suffered numb fingers, headaches, dizziness, depression and impotence.
He was advised to stop work and one year later reported a remarkable improvement in mood and said the outside world seemed clearer.
However, he still felt irritable, had a poor memory and had lost his sense of smell.