New York, Dec 30 (IANS): Welders exposed to airborne manganese at estimated levels set under federal safety standards can also develop neurological problems like Parkinson's disease and the current safety standards may not adequately protect workers from the dangers of the job, a new research has found.

According to a study published in the journal Neurology, the more welders are exposed to manganese-containing welding fumes, faster the workers' signs and symptoms worsen.

"We found that chronic exposure to manganese-containing welding fumes is associated with progressive neurological symptoms such as slow movement and difficulty in speaking," said Brad A. Racette, Professor at Washington University in St. Louis, US.

The researchers explained that at high levels, manganese can cause manganism, with symptoms like slowness, clumsiness, tremors, mood changes and difficulty in walking and speaking.

Researchers suspected that there may still be some health effects at levels much lower than what is allowable per standards set by Occupational Safety and Health Administration (OSHA) standards decades ago.

"Many researchers view what is allowable as too high a level of manganese, but until now there really were not data to prove it," said Racette.

The researchers studied 886 welders at three sites. They found that the neurological signs showed up in people with an estimated exposure of only 0.14 mg of manganese per cubic meter of air, far below the safety standard set by OSHA at five mg per cubic meter.

The American Conference of Governmental Industrial Hygienists had recommended in 2013 that the limit should be brought down to 0.02 mg of manganese per cubic meter.

"Reducing OSHA's allowable levels of manganese would probably make a big difference in terms of safety and help workers avoid such risks," Racette suggested.