Toxic substance list: tributyltins (TBTs)
Tributyltins (TBTs) are part of a group of substances called organotins, which are mainly used in the processing of PVC (a type of plastic) and as pesticides. TBTs for non-pesticidal uses are no longer manufactured or used in Canada as a primary material, but may be present in other organotin products (mono- and dibutyltins containing less than 1% of TBTs and tetrabutyltin containing up to 30% of TBTs).
The Follow-up to the 1993 Ecological Risk Assessment of Organotin Substances on Canada’s Domestic Substances List was published by Environment Canada in the Canada Gazette, Part I on August 8, 2009, under section 68 of the Canadian Environmental Protection Act, 1999 (CEPA). This assessment report concluded that non-pesticidal TBTs are entering, or may enter, the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity, as defined in paragraph 64(a) of CEPA.
Based on the conclusions of the assessment, it was therefore recommended that non-pesticidal TBTs be added to Schedule 1 of CEPA. Additionally, tributyltins meet the criteria for persistence and bioaccumulation potential as set out in the Persistence and Bioaccumulation Regulations.
In addition, Health Canada conducted in 2003 an assessment of the human health effects of non-pesticidal organotins and concluded that non-pesticidal organotins, including tributyltins, do not meet the criteria set out under paragraph 64(c) of CEPA.
TBTs were added to the Prohibition of Certain Toxic Substances Regulations, 2012. Furthermore the following initiatives are in place or are being developed to manage any potential release of substances where TBTs may be present:
- An Environmental Performance Agreement Respecting the Use of Tin Stabilizers in the Vinyl Industry has been in place since March 10, 2008, to manage the release of tin stabilizers (mono- and dibutyltins) into the environment, including any TBTs that may be present in the stabilizers.
- A Code of Practice is currently being developed under section 54 of CEPA to manage releases of tetrabutyltin to the aquatic environment, including any potential release of TBTs that may be present in tetrabutyltin. This would apply to all facilities involved with tetrabutyltin in Canada.
- With respect to pesticidal uses of TBTs, the use of TBTs in anti-fouling paints (which are used to coat the bottoms of ships to prevent sea life from attaching themselves to the hull) on ship hulls has been prohibited in Canada since 2002, following the special review by Health Canada's Pest Management Regulatory Agency. In addition, a proposed re-evaluation decision for tetrabutyltin compounds was published on July 15, 2010, which proposed a phase-out of the remaining pesticidal uses of TBT compounds as a material preservative, under the Pest Control Products Act. A final regulatory decision is pending consideration of comments received during the consultation process.
For more information on organotin substances, please visit the Chemical Substances Website.
- CEPA Schedule 1 - List of Toxic Substances – This substance has been added to the List of Toxic Substances (item 113). It is entering or may enter the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity.
- Final Order Adding TBTs to Schedule 1 to the Canadian Environmental Protection Act, 1999 (June 2011)
- Follow-up to the 1993 Ecological Risk Assessment of Organotin Substances on Canada's Domestic Substances List (August 2009)
- Follow-up Report on Non-Pesticidal Organotin Compounds for Which Data Were Insufficient to Conclude Whether the Substance Was “Toxic” to Human Health (May 2003)
Risk Management Strategy
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Risk Management Tools
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