Canadian Biocide Labeling Change Debated


A Canadian proposal to lower application rates for a formaldehyde-free biocide based on a mixture known as CMIT/MIT has drawn opposition over concerns it would reduce the biocides effectiveness in metalworking fluids.

The mixture is 5-chloro-2-methyl-2H-isothiazol-3-one and 2-methyl-2H-isothiazol-3-one (CMIT/MIT), which had historically been approved for use in Canada at 15 parts per million.

The Pesticide Management Regulatory Agencys decision to reduce the maximum CMIT/MIT application rate was based on review of at least a dozen published studies, a Health Canada spokeswoman said. Following the review of the relevant scientific studies, PMRA concluded that the maximum CMIT/MIT application rate should be reduced to mitigate health risks of concern from the sensitization effects of CMIT/MIT, Anna Maddison told a reporter. For metalworking fluid use, the maximum CMIT/MIT application rate is to be reduced to 8 parts per million.

Maddison said that all registrants with affected products were informed of the decision and were required to file an application to revise their product labels. Health Canada can confirm that all registrants have submitted an application, as requested, she said. The review of these applications will take up to nine months. Once approved, the revised labels will be available on PMRAs website.

In its April 28 ILMA Digest, the Independent Lubricant Manufacturers Association said it sent a letter to the agency, urging it to maintain its existing use rate for formaldehyde-free biocides based on the chemical mixture. The associations Metalworking Fluid Committee discussed the issue in April and said it would monitor it closely going forward.

The association noted in its letter both the longstanding and effective use of CMIT/MIT to combat microbial growth in water-based metalworking fluids and the implications for fluid replacement and worker health and safety if fluids become contaminated due to ineffective biocide treatment levels. Further, ILMA commented on the noxious odors that could result from microbial growth at the lower biocide levels during weekends, holidays and other extended periods when machines are not running, the association noted in its weekly public policy update.

According to a presentation at the MWF Committee meeting, the American Chemistry Council formed a task force to address PMRAs assessment and held a conference call with the agency on April 10. The task force discussed benefits of CIT/MIT and provided information on toxicity, assessment considerations and the impact of lower use levels. The task force requested a delay in label amendments, noting that the impact is large both for registrants and end-users, and it requested additional consideration for conclusions regarding use levels. According to the presentation, PMRA and Health Canada signaled during the call that they were open to hearing from end-users regarding efficacy concerns. The MWF Committee asked ILMA to send a letter to PMRA and Health Canada expressing association members concerns. The American Chemistry Council declined to comment for this story.

From a technical perspective, the issue is that the new Canadian maximum permissible end use concentrations are below CIT/MITs minimum effective concentration, Fred Passman of Biodeterioration Control Associates, Inc. of Princeton, N.J. told Lube Report. And the driving motivation for making the change was PMRAs concern over skin sensitization. From what I understand, the skin sensitization is linked to exposure to the personal care products preserved with MIT, and not necessarily the CIT/MIT under attack by PMRA.

Passman noted that while the Canadian market isnt large compared to the U.S. or the European Union, it still is a significant market, and the proposed change does have some repercussions.

In an emailed statement, Health Canada said PMRA regularly re-evaluates registered pesticides to determine whether they continue to be acceptable according to current health and environmental safety standards. Canadas Pest Control Products Act requires pesticides to be reviewed every 15 years as a minimum.

The agency said it re-evaluated biocide products containing CMIT/MIT in 2005 and as a result required additional data from registrants of biocides containing CMIT/MIT to assess the potential sensitization risk to workers and consumers handling treated materials containing these chemicals.