Chlorinated Naphthalenes (CNs) are a group of chemical substances that may be released as by-products of industrial processes. There are 75 possible CNs which are divided into eight groups based on the number of chlorine atoms in the molecule (referred to with prefixes mono- to octa-)
How are they used?
CNs have not been in commercial use in Canada for more than two decades, but may be produced unintentionally as a by-product of various industrial processes involving chlorine.
CNs were likely never manufactured in Canada but were imported from manufacturers in the U.S. decades ago.
Why is the Government of Canada assessing them?
CNs were identified as a potential danger to the environment based on available information regarding possible persistence, accumulation in organisms and potential to cause harm to organisms.
How are they released into the environment?
Because CNs are produced unintentionally as by-products of industrial processes, they may be released to the environment from a variety of sources. They can then stay in the environment for a long time.
Industrial processes involving chlorine (especially in the presence of heat) that may produce CNs as a by-product include waste burning, cement and magnesium production, refining of metals, drinking water chlorination and pulp and paper production.
CNs can also be released to the atmosphere from domestic wood-burning, or naturally during forest fires.
CNs tend to be present in air and/or soil if released to air, and in water and sediment if released to water.
CNs may enter the environment in a sufficient quantity or under conditions that would be harmful to the environment and its biological diversity.
What is the Government of Canada doing?
The Government of Canada has conducted a science-based evaluation of CNs called a screening assessment.
The Government of Canada has determined that CNs with two to eight chlorine atoms (di- through octa-) are entering or may enter the environment in a quantity or under conditions that may constitute a danger to the environment.
What can Canadians do?
Because exposure to CNs is very low, Canadians do not need to take specific actions to reduce their exposure.
