ST. LOUIS _ Current safety standards to protect welders from harmful fumes may be inadequate, a new study by Washington University, St. Louis, researchers finds.
The study, published Wednesday in the medical journal Neurology, examined the long-term effects of airborne manganese on welders and found that symptoms associated with parkinsonism _ a neurological condition that causes tremors, muscle stiffness and other movement abnormalities _ increased over time.
"Essentially, the more exposure you had the greater the progression of the parkinsonism. Even at the lower levels of exposure we saw progression _ just not as much," said Dr. Brad A. Racette, senior author of the study and a neurologist with Washington University School of Medicine.
Manganese is present in the materials used in welding, including the base metal and the welding rod, and when it becomes airborne and inhaled it can affect the part of the brain that controls movement _ the same part that's affected in Parkinson's disease, Racette said.
High levels of manganese can cause similar neurological problems present in Parkinson's disease like slowness, tremors and difficulty walking and speaking.
The study examined 886 welders at three work sites in the Midwest _ two shipyards and one heavy-machinery fabrication shop. None of the work sites were located in St. Louis, Racette said.
Each participant had at least two clinical evaluations of their motor function and were tracked for up to 10 years.
The two tests were at least a year apart and looked for muscle stiffness and slow movement, among other symptoms.
The test used to measure the symptoms is called Unified Parkinson's Disease Rating Scale.
Scoring a six or lower is normal while 15 or higher is considered to have parkinsonism, according to Racette's study.
The average score for the 886 workers' first evaluation was 8.8. Fifteen percent, or 133 welders, fell into the parkinsonism category.
The welders' scores increased over time. And the welders who were exposed to higher levels of manganese experienced greater changes in their scores.
However, Racette said a limitation of the study was that they were never able to measure the air quality of the welders' work environments.
"While that's not ideal, we're looking at long-term health effects from chronic exposure," Racette said. "Our study can't answer what safe is but what we can say is the current government limits are far too high for worker safety."
The study did conduct the same tests on workers at the same sites who were not directly exposed to welding fumes. Their scores did not change over time, indicating to Racette that age was not a factor.
What's concerning, Racette said, is that the study suggests that welders with worsening neurological symptoms were exposed to airborne manganese at levels below the maximum threshold allowed by federal regulators.
There were 7,660 welders, cutters, solderers and brazers in Missouri as of May 2015 and 386,240 nationwide, according to the Bureau of Labor Statistics.
The Occupational Safety and Health Administration, or OSHA, the federal agency responsible for workplace safety, acknowledged its current thresholds fail to protect welders.
"OSHA has long recognized that our current Permissible Exposure Limit is outdated and inadequately protective, and we strongly recommend that employers ensure that workplace manganese exposure levels are well below OSHA's standard," Dr. David Michaels, assistant secretary of labor for Occupational Safety and Health, said in an email statement provided by the agency.
Garrett Brown, a retired industrial hygienist who worked for the California Division of Occupational Safety and Health for 20 years, said the Washington University findings could bolster the case for updating safety guidelines.
"In toxicology, there is very rarely a bright red line of what is a safe exposure," Brown said. "It's very important for studies like this to add to the body of knowledge on what adverse health effects occur and at what limits."
But while the current exposure limits "are way out of date," Brown said the current anti-regulatory political climate may make it "unbelievably difficult to change these (standards) no matter how good the science is."
Rick Bretl, 61, of Menominee, Mich., who participated in the study for nearly a decade, worked as a welder since he was a teenager. He was employed at a shipyard for 20 years until he had to retire after an accident.
He received training classes on welding while in the service, and it was there that he learned about the dangers of welding fumes. From that point on, early in his career, he always wore a mask and later one with a respirator or ventilation system.
But not every welder was taught about the dangers and not every welder wore a mask.
"Sometimes you're in a big open area and they'll last a week," Bretl said of the respirators. "But some days you go in to a place the size of a closet and you're welding in there and you may have to change that at lunch time. That's how much stuff you're breathing in."
Bretl said he hasn't experienced any of the hallmark signs of Parkinson's disease. But because of the accident he incurred, he can't do any physical activity and was forced to retire last year.
