Mixing Unknown Unknowns Testing TSCA and GHS against Metalworking Fluids
In my former position as director of health and safety for the United Auto Workers, I participated in many meetings about chemical exposures in which UAW members would “invent” for themselves the goals of the Toxic Substances Control Act. They would say that chemicals should be tested before the members themselves were exposed, the dangerous chemicals eliminated and the others controlled to “safe” levels. Of course, TSCA was in effect, and it wasn’t doing the job. UAW’s comments on TSCA in 1976 noted that the Act’s emphasis on “new” chemicals was incomplete. The UAW believed that the main danger to workers (and communities) came from existing chemicals and products that were mixtures, including metalworking fluids (MWFs).

Early UAW and other studies had found excess mortality from cancer among workers exposed to MWFs in the manufacture of engines, transmissions, and other parts for autos. These findings led to jointly administered research funds, which launched more extensive studies of MWFs. A Harvard team published results showing increased respiratory issues in 1989 and increased cancer in 1992. In 1993, the UAW petitioned OSHA for a standard for MWFs; NIOSH for a criteria document, which was issued in 1998; and EPA for a TSCA testing rule.
Section 4 of TSCA, “Testing of Chemical Substances and Mixtures,” provides EPA with the authority to compel manufacturers to conduct chronic exposure studies for respiratory and cancer effects. UAW’s intent was to identify the specific ingredients responsible and relative potencies of mixtures so that substitutes could be found or other control measures imposed.
I met with a staffer at EPA (name and date lost to memory) who said there was no need for testing, since OSHA would regulate exposure to the lowest feasible level if my claims on epidemiology were correct, and anyway it would take years to promulgate a rule to require testing, which would not be a priority. I judged that the UAW could never litigate our way to a testing rule. CARCINOGENIC POTENTIAL Eventually, the UAW tried to litigate to an OSHA standard. There were many steps between UAW’s 1993 petition, OSHA’s final denial of the petition in 2003, and a 3rd Circuit Court of Appeals decision in 2004 flushing the case. The three judges noted:

There is little doubt, and it is not disputed here, that exposure to MWFs can have debilitating health effects.... While there is little debate about the link between MWF exposure and respiratory disorders and dermatitis (again, the debate is over the severity and prevalence), the evidence supporting a connection to cancer is equivocal at best. The opinion gave OSHA a free ride to say no to any petition for a standard, based on OSHA’s unreviewable claim of priorities and resources. So both the Court and OSHA viewed carcinogenic potential as key. And a conclusion of carcinogenic potential depended in part on laboratory evidence.
With EPA’s testing rule off the table, the National Toxicology Program’s recently published toxicity studies on MWFs offer another road to data. This extensive toxicology program identified “representative” MWFs and resulted in two reports on chronic studies and two on ninety-day studies. The key findings were:
  • A two-year chronic study of a soluble oil formulation found “clear” evidence for carcinogenicity in lungs for both genders of rats and “equivocal” evidence for both genders of mice.
  • A study of a semi-synthetic MWF found “some” evidence for carcinogenicity in female mice (lung and thyroid) and equivocal evidence in both genders of rats.
  • As reported in a paper published online this past July by Toxicology and Industrial Health, the ninety-day studies for four representative MWFs found essentially 100 percent respiratory histopathology of at least one diagnosis at the lowest dose tested—10 mg/m3 for the chronic and 25 mg/m3 for subchronic.
  • Of the additional five MWFs considered, short-term studies (genetic toxicology) were not predictive of chronic results for all nine, including the two found carcinogenic in two-year studies.
There’s not a straight line between findings of respiratory pathology and warnings on an SDS.
FRANK MIRER, PhD, CIH, is a professor in the CUNY School of Public Health in New York. He can be reached at (212) 396-7782 or fmirer@hunter.cuny.edu.