Recent findings by researchers at the Washington University School of Medicine in St. Louis suggest the Occupational Safety and Health Administration’s (OSHA) permissible exposure limit (PEL) for manganese should be lowered, according to the school’s website. The study shows OSHA’s manganese limits may be endangering workers.
Questions about the health effects of manganese, a trace element used mostly in steel production to improve hardness and strength, dates back to at least the 1990s, when the Agency for Toxic Substance and Disease Registry (ATSDR) was completing a toxicological profile on it, according to the National Institutes of Health.
This most recent study found workers exposed to airborne manganese at levels well below OSHA’s PEL of 5 milligrams of manganese per cubic meter or air (mg/m3) developed problems similar to Parkinson’s disease, which affects the body’s nervous system.
ATSDR’s public health statement on manganese notes the most common health problem for workers exposed to high levels of manganese involve the nervous system with effects including behavioral changes and slow and clumsy movement—most severely in a condition known as manganism.
“Other less severe nervous system effects such as slowed hand movements have been observed in some workers exposed to lower concentrations in the work place,” the organization states.
The findings, published Dec. 28 in the journal Neurology, found neurological signs appeared in workers with an estimated exposure of only 0.14 mg/m3, suggesting even low exposure rates can have a significant impact.
“We found that chronic exposure to manganese-containing welding fumes is associated with progressive neurological symptoms such as slow movement and difficulty speaking,” said Brad A. Racette, MD, a professor of neurology and the study’s senior author. “The more exposure you have to welding fumes, the more quickly those symptoms progress over time. Many researchers view what’s allowable as too high a level of manganese, but until now there really weren’t data to prove it.”