WASHINGTON (CN) – The D.C. Circuit on Friday ruled against industry groups challenging a Labor Department rule that limits workers’ exposure to the chemical compound silica, but agreed that the rule is missing a provision for already exposed workers to be pulled off the job site.
In March 2016, the Occupational Safety and Health Administration, or OSHA, an agency of the U.S Department of Labor, published the rule regulating exposure to silica by the more than 2 million workers it says come into contact with some form of the compound.
Silica is most often found at work sites with rock, sand, gravel, concrete and brick. Prolonged exposure can cause silicosis, a type of lung disease, and even death.
In a challenge to the rule last year, the North America Building Trade Union and others argued OSHA’s findings on the effects of silica exposure were questionable. The U.S. Chamber of Commerce intervened in the case on behalf of the unions and industry entities.
But the D.C. Circuit found in an unsigned order issued Friday that OSHA’s use of a “no threshold exposure response model” to assess silicosis risk was satisfactory. The model means there is “no exposure level below which workers would not be expected to develop adverse health effects,” according to the ruling.
Industry groups contend OSHA never definitively found this to be the case. Instead, they argued, OSHA’s standard was “inconsistent with common sense” and “mounting judicial skepticism of no-threshold models.”
The Washington, D.C.-based appeals court was satisfied with the integrity of OSHA’s findings, saying the agency’s reliance on two studies – referred to as the Mannetje study and the Park study – showed “a statistically significant association between silicosis mortality and cumulative exposure.”
While trade groups argued the Park study data was skewed due to an unknown number of respondents who smoke - therefore increasing the likelihood of lung disease – the court found OSHA can rely on imperfect evidence.
“OSHA did recognize and account for the weaknesses of the two studies it relied on here,” the ruling states.
The D.C. Circuit questioned one study relied on by OSHA connecting silica exposure to kidney failure, but found that its other evidence on health effects related to such exposure supported the contested rule.
“We need not and do not decide whether OSHA supported its renal disease findings with substantial evidence because OSHA’s findings with respect to silicosis and [non-malignant respiratory disease] mortality, lung cancer mortality, and silicosis morbidity are sufficient to uphold the requisite threshold finding of a significant risk of material health impairment,” the ruling states.
The court also rejected arguments by the U.S. Chamber of Commerce claiming laborers in the brick industry should be excluded from the silica-exposure rule altogether.
OSHA argued brick workers should be covered by the rule based on findings in what is referred to as the Love study, a survey that found just over 1 percent of brick workers discovered “small abnormalities” in their lungs during an x-ray. The study’s authors said the abnormalities were “most likely silicosis.”