The risks posed by a substance are determined both by its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent of exposure to people and the environment.
When needed, the Government implements risk management measures under CEPA 1999 and other federal acts to help prevent or reduce potential harm.
The Government is proposing that MSP may be harmful to the environment due to potential effects on aquatic organisms at very low levels of MSP exposure.
Monomethylstyrenated phenol is expected to persist in the environment but is unlikely to bioaccumulate in organisms.
The other two major components of MSP (dimethylstyrenated phenol and dimers of C9 monomer) are expected to persist and to significantly bioaccumulate in organisms.
The Government is proposing regulatory and non-regulatory actions to address the ecological concerns.
MSP is associated with health effects; however, at levels of exposure considered in the assessment, the Government is proposing to conclude that this substance is not harmful to human health.
MSP is an UVCB substance, meaning that it is of Unknown or Variable composition, Complex reaction products and Biological materials. The major components of the substance are monomethylstyrenated phenol, dimethylstyrenated phenol, and dimers of 2-phenylpropene (C9) monomer.
MSP was previously assessed in 2008 as part of the Final Screening Assessment for Potentially Toxic Substances [145 Persistent Bioaccumulative and inherently Toxic (PBiT) substances] under the CMP. As no exposure to Canadians or the environment was identified at that time, the Government concluded that MSP was not harmful to human health or to the environment. Due to environmental concerns over its hazardous properties, the Significant New Activity (SNAc) provisions of CEPA 1999 were applied to MSP in April 2008. This requires that the Government be notified of certain proposed new activities related to MSP and that these be assessed for potential risks to human health and/or the environment before being undertaken.
Multiple Significant New Activity Notifications (SNANs) were received between 2015 and 2018, indicating that new uses were being proposed.
According to information gathered by the Government, this substance is mainly used in Canada in paints and coatings for ships and large industrial equipment.
This substance is not expected to occur naturally in the environment.
Human and ecological exposures
MSP may be released to surface water from industrial uses of coatings for ships and large industrial equipment. Presence of MSP in sediment and soil is also possible.
Canadians may be exposed to MSP from environmental sources, such as drinking water.
Key health and ecological effects (hazard)
The critical effects identified for characterizing the risk to human health in the screening assessment included decreases in body weight and food consumption.
Components of MSP have been shown to cause effects in aquatic organisms at very low levels, and are associated with endocrine effects. Components of MSP are also expected to persist in the environment and have high bioaccumulation potential in aquatic organisms.
Risk assessment outcomes
A comparison of levels to which Canadians may be exposed to MSP, and levels associated with health effects indicated that the risk to human health for this substance is considered to be low.
Considering all information presented, it was determined that there is risk of harm to aquatic organisms from MSP.
Proposed screening assessment conclusions
The Government is proposing that MSP is not harmful to human health at levels of exposure considered in the assessment; however, the Government is also proposing that MSP is entering or may enter the environment at concentrations that may be harmful to the environment.
If the proposed conclusion is confirmed in the final screening assessment, the Government will consider adding MSP to Schedule 1 of CEPA 1999, also called the List of Toxic Substances. Adding a substance to the list does not restrict its use, manufacture or import. Rather, it enables the Government to take risk management actions under CEPA 1999.
The Government will consider the following actions to address ecological concerns:
Regulations to prohibit the manufacture, use, sale, offer for sale, and import of MSP and products containing the substance;
Regulatory and non-regulatory initiatives to prevent or limit releases of MSP from notified activities during an interim phase-out period, if warranted;
Information is being sought by the Government to inform risk management decision-making. Details can be found in the risk management scope, including where to send information during the public comment period, ending January 5, 2022.
Risk management options may evolve through consideration of assessments and risk management options or actions published for other substances. This is to ensure effective, coordinated, and consistent risk management decision-making.