In her presentation, “Global Nickel Developments for Surface Finishing,” Dr. Oller cited both conclusive studies and independent scientific research that dispels some misperceptions about soluble nickel compounds. Referencing a research article published earlier this year that reviewed the epidemiologic data that was integrated into a weight of evidence evaluation of the carcinogenicity of soluble nickel compounds, she conveyed the following: both the epidemiological and animal data provide no more than limited evidence for the human carcinogenicity of soluble nickel and, therefore, do not support a causal association. Furthermore, the article showed, the weight of evidence does not clearly support a role for soluble nickel alone in carcinogenesis. Although there is weak evidence consistent with it being a promoter in a narrow range of tissues, the data are also compatible with soluble nickel not having tumor-promoting activity.
“The good news is nickel will live to fight another day at another battle,” Dr. Oller said. “Nickel metal is not an issue at the moment.”
The findings were buttressed by additional studies—these involving animal tests—that concluded chronic inhalation of metallic nickel was not carcinogenic to the respiratory tract of rats. Among the main findings: Increased tumors in adrenal medulla were found; and the tumors in males were considered exposure-related but not nickel-specific (secondary to lung toxicity). Additionally, increased tumors in one group of females fell in range of historical control. The negative results, the study found, are consistent with a lack of association between metallic nickel exposures outside of sulfidic ore refineries and increased respiratory cancer risks.(Notable respiratory toxicity effects were observed in rats at exposure levels of 0.1 mg Ni/m3.)
As it pertains to metal-related regulatory activities, Dr. Oller believes the findings further the nickel and surface finishing industries’ goals to promote the declassification of nickel metal and encourage the proper use of toxicity data for OEL setting. Among the primary objectives:
- Specify inhalation as the only route of exposure concern to humans
- Avoid nickel metal getting classified any higher than Group 2B
- Clarify that carcinogenicity of nickel compounds in humans may be limited to sulfidic ore processing/refining exposures
- Consider that mode of action for carcinogenicity of soluble nickel may differ from that of insoluble nickel and may be non-genotoxic (threshold effect)
Although the outcome of the aforementioned study was discussed at a critical Committee on Hazardous Substances meeting in Germany earlier this year, it was the recommendation of a “working group” that a Category 3 classification (suspect human carcinogen) be maintained for nickel metal. A similar recommendation was made a few months later during a meeting of the
International Agency for Research on Cancer (IARC). In short, the working group declared that a “re-evaluation of nickel metal can be expected in the near future.”
To that end, Dr. Oller, on behalf of the
Nickel Institute, has outlined a strategy to contend with future regulatory challenges. From a “science” perspective, that means "updating relevant epidemiological studies and collecting in vitro and animal data showing different responses for metallic nickel vs. insoluble compounds."
As it relates to “policy,” the next move entails: registering a complaint and requiring text clarification; nominating “experts” for future nickel metal discussions; and lobbying IARC country members to assure fair treatment of nickel metal.
This is surely easier said than done, especially as it pertains to the metals classification process and combating a regulatory mindset whereby far-reaching decisions impacting industry are not completely grounded in science. So says Chris Bell, a partner in the law firm Sidley Austin. In his presentation, “Update on Changes in the EU Classification Rules and Nickel Classifications, Bell goes straight to the heart of the issue.
"People don’t naturally make distinctions between nickel compounds and nickel metals," he said. "I’ve heard stories of some customers saying they don’t want SVHCS [substances of very high concern] in their product—they don’t want to hear anything you have to say."
(For more on this story, please see the July/August issue of Metal Finishing, due to mail July 30.)