Mitotane – information sheet

Benzene, 1-chloro-2-[2,2-dichloro-1-(4-chlorophenyl)ethyl]-

CAS Registry Number 53-19-0

What is it?

  • The substance, benzene, 1-chloro-2-[2,2-dichloro-1-(4-chlorophenyl)ethyl]-, also known as mitotane, is a pharmaceutical chemical.

How is it used?

  • Mitotane is used as an active ingredient in prescription medication as a therapeutic cancer drug. In Canada, mitotane as a drug is regulated under the Food and Drugs Act and is registered in Health Canada's Drug Product Database.
  • Mitotane is also an impurity in, and a degradation product of, some pesticides, and although these pesticides are no longer used in Canada, mitotane may be found in the environment from historical pesticide uses.
  • Mitotane is not manufactured in Canada, but is imported into Canada.

Why did the Government of Canada assess it?

  • Prior to the assessment, mitotane was identified as a potential concern to the environment based on information regarding possible persistence, accumulation in organisms and potential to cause harm to organisms.
  • However, mitotane was not considered to be a priority for assessment of potential risks to human health. Regardless, potential health effects were also evaluated in this screening assessment.

How are Canadians exposed to it?

  • The general population in Canada may be exposed to mitotane through the environment; however, exposure is expected to be low.

How is it released into the environment?

  • The substance is present in the environment primarily due to historical pesticide use.
  • Mitotane may also be released in small quantities to the aquatic environment through wastewater treatment system effluent following its use as a therapeutic cancer drug or from the degradation of remaining dichlorodiphenyltrichloroethane (DDT) in the environment.

What are the results of the assessment?

  • The Government of Canada has conducted a science-based evaluation of mitotane, called a screening assessment.
  • Screening assessments address the potential for harm to the general population of Canada and the environment.
  • Results of the final screening assessment indicate that mitotane has the potential to remain in the environment for a long time and accumulate in organisms.
  • Furthermore, the quantity of mitotane that has the potential to be released to the environment from its use as a drug is above the level expected to cause harm to organisms.
  • The Government of Canada has therefore concluded that mitotane is entering or may enter the environment at levels that constitute a danger to the environment, and meets the criteria for virtual elimination (set out in the Canadian Environmental Protection Act, 1999 (CEPA 1999). However, virtual elimination of the release of mitotane to the environment will not be implemented because of its unique use as a therapeutic cancer drug.
  • The Government of Canada has also concluded that mitotane is not harmful to human health at current levels of exposure.

What is the Government of Canada doing?

  • The Government of Canada published the Final Screening Assessment for Mitotane and the Proposed Risk Management Approach Document for Mitotane on October 28, 2017. The proposed risk management approach will be followed by a 60-day public comment period, ending on December 27, 2017.
  • Given the limited application of mitotane as a therapeutic cancer drug, the application of the Significant New Activity Notice (SNAc) provisions of CEPA 1999 will be proposed as the most appropriate risk management action. This would require that the Government of Canada be notified of any proposed new activities related to the substance (for example, use of the substance under different circumstances other than its use as a therapeutic cancer drug). It would be subject to further assessment to determine if the new activity requires further risk management consideration.
  • No risk management actions are being proposed to limit the use of mitotane as a therapeutic cancer drug.
  • View more information on risk management action milestones for mitotane.

What can Canadians do?

  • The health risks associated with a chemical depend on the hazard (its potential to cause health effects) and the amount of chemical to which a person is exposed. Mitotane is not presently a concern for human health at current levels of exposure.
  • Canadians are encouraged to dispose of unused and expired medication in an environmentally safe manner. Pharmaceutical take-back programs exist in many provinces and territories. For more information about pharmaceutical take-back programs, please speak with your local pharmacy.
  • Canadians who may be exposed to mitotane in the workplace should consult with their employer and occupational health and safety (OHS) representatives about safe handling practices, applicable laws and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).
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