Phenol, methylstyrenated - information sheet

Methylstyrenated Phenol (MSP)
CAS Registry Number68512-30-1

Publications summarized

• Draft Assessment for Phenol, Methylstyrenated (published on January 17, 2026). Public comments received on the previous draft assessment and risk management scope (published November 3, 2021) were considered and a summary of the comments with Government responses was published.
• Revised Risk Management Scope for Phenol, Methylstyrenated (published on January 17, 2026 for a 60-day public comment period ending on March 18, 2026).
• Associated notice: Canada Gazette, Part I: Vol. 160, No. 3 – January 17, 2026.

On this page

• Overview
• About this substance
• Human and ecological exposures
• Key health and ecological effects (hazard)
• Consideration of subpopulations who may have greater susceptibility or greater exposure
• Risk assessment outcomes
  • Proposed assessment conclusions
• Preventive actions and risk reduction
  • Where to find updates on risk management actions
• Related resources

Overview

• The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA) to determine whether they present or may present a risk to human health or to the environment.
  • The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent to which people or the environment are exposed.
  • When needed, the Government implements risk management measures under CEPA and other federal acts to help prevent or reduce potential harm.
• The Government is proposing to conclude that MSP may be harmful to the environment due to potential effects on aquatic organisms at very low levels of exposure.
  • Monomethylstyrenated phenol is expected to persist in the environment, but is unlikely to bioaccumulate in organisms.
  • The other two major parts of MSP (dimethylstyrenated phenol and dimers of C9 monomer) are expected to persist and to significantly bioaccumulate in organisms.
• The Government is proposing 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.

About this substance

• The assessment focused on phenol, methylstyrenated, also referred to as MSP under the Chemicals Management Plan (CMP).
• MSP is an UVCB substance, meaning that it is of Unknown or Variable composition, Complex reaction products and Biological materials. The major parts 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 people in Canada 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 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 since 2015, indicating that new uses were being proposed. Therefore, the Government decided to reassess MSP, taking these new uses into account.
• According to information gathered by the Government, this substance is mainly used in Canada in paints and coatings for ships and large industrial equipment.

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.
• People in Canada 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 assessment included decreases in body weight and food consumption.
• Parts of MSP have been shown to cause effects in aquatic organisms at very low levels, and are associated with endocrine effects. Parts of MSP are also expected to persist in the environment and have high bioaccumulation potential in aquatic organisms.

Consideration of subpopulations who may have greater susceptibility or greater exposure

• There are groups of individuals within the Canadian population who, due to greater susceptibility or greater exposure, may be more vulnerable to experiencing adverse health effects from exposure to substances.
• Certain subpopulations are routinely considered throughout the assessment process, such as infants, children, and people of reproductive age. For instance, age-specific exposure estimates are routinely derived and developmental and reproductive toxicity studies are evaluated for potential adverse health effects
• In addition, people living near industrial releases were considered in the assessment of MSP.

Risk assessment outcomes

• Assessments focus on information critical to determining whether substances are harmful to human health or the environment under CEPA. This is done by considering scientific information, including information, if available, on subpopulations who may have greater susceptibility or greater exposure, vulnerable environments and cumulative effects and by incorporating a weight of evidence approach and precaution.
• A comparison of levels to which people in Canada 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 a risk of harm to aquatic organisms from MSP.

Proposed assessment conclusions

• The Government is proposing to conclude that MSP is not harmful to human health at levels of exposure considered in the assessment; however, the Government is also proposing to conclude that MSP is entering or may enter the environment at concentrations that may be harmful to the environment.
• The Government determined that MSP meets the persistence and bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA.

Preventive actions and risk reduction

• The Government will consider proposing to add MSP to Part 1 of Schedule 1 to CEPA. Adding a substance to Schedule 1 does not, in itself, restrict its use, manufacture or import. Rather, it enables the Government to take enforceable risk management actions under CEPA.
  • Toxic substances that pose the highest risk (that is, meet certain criteria) are added to Part 1 of Schedule 1. These are prioritized for total, partial or conditional prohibition.
  • Other toxic substances are added to Part 2 of Schedule 1 and are prioritized for pollution prevention actions, which may include prohibition.
• Publication of the revised risk management scope aims to inform interested parties of proposed risk management actions and initiate discussions about their development. The revised risk management scope indicated that the Government is considering the following actions to address ecological concerns:
  • Amending the Prohibition of Certain Toxic Substances Regulations, 2025, to prohibit the manufacture, use, sale, offer for sale, and import of MSP and the products that contain the substance
  • Upon prohibition of MSP, such as through its addition to the Prohibition of Certain Toxic Substances Regulations, 2025, the Government of Canada would also add MSP to Part 3 of the Export Control List in Schedule 3 to CEPA to subject its export to the Export of Substances on the Export Control List Regulations.
• Additional 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 March 18, 2026.
• Risk management actions may evolve through consideration of assessments and risk management actions published for other substances. This is to ensure effective, coordinated, and consistent risk management decision-making.

Where to find updates on risk management actions

• The timeline on the MSP web page is updated to reflect new or changed activities.
• Up-to-date information on Regulations Amending the Prohibition of Certain Toxic Substances Regulations, 2025 and the risk management of substances addressed under the CMP is available.
• Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.

Related resources

• Assessments conducted under CEPA focus on risks of exposure of the general population, including populations who may be disproportionately impacted. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). The Government of Canada recognizes that it is the responsibility of the federal, provincial and territorial occupational health and safety organizations to coordinate legislation for the safe use of chemicals in the workplace. We are working to support this role by integrating the information, tools, and/or technical expertise of the CMP and Health Canada's Workplace Hazardous Products Program.