TRIANGLE PARK, NORTH CAROLINA. Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a neurodegenerative disease that results in muscle wasting and weakness. It is usually fatal within 2 to 5 years of onset. Fortunately, ALS is relatively rare (1-2 cases per 100,000 people); it affects more men than women and is inherited in about 5-10 per cent of cases. Oxidative stress, cigarette smoking, exposure to heavy metals, pesticides, solvents and electromagnetic fields have all been implicated as possible causative factors.
Researchers at the National Institute of Environmental Health Sciences now report convincing evidence that occupational exposure to lead is a potent risk factor for ALS. Their study involved 109 ALS patients and 256 healthy controls. All participants were interviewed to determine their lifetime lead exposure and had blood samples drawn for determination of lead levels. Lead levels were also measured in bones (knee cap and shin bone) using x-ray fluorescence. The researchers found that ALS patients were 1.9 times more likely to have had occupational exposure to lead than were the controls. Most frequently cited occupations were soldering, battery manufacture or reclamation, painting or paint removal, and working with firearms. Residential or recreational exposure to lead was not associated with an increased risk of ALS. Lead levels in the blood, patella (knee cap), and tibia (shin bone) of ALS patients were found to be substantially higher than in the controls.
The researchers conclude that occupational lead exposure could substantially increase the risk of ALS.
They speculate that lead may act through its known propensity to cause oxidative stress and mitochondrial