Sulfurized isobutylene - information sheet

1-Propene, 2-methyl-, sulfurized
CAS Registry Number 68511-50-2

Publications summarized:

Final Screening Assessment for Sulfurized Isobutylene (published on May 14, 2022). Public comments received on the draft screening assessment were considered and a summary was published.
Associated notice: Canada Gazette, Part I: Vol. 156, No. 20 – May 14, 2022

The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA 1999) 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 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 ecological hazard and exposure potentials of this substance were classified using the Ecological Risk Classification of Organic Substances (ERC) Approach.
Sulfurized isobutylene is associated with health effects; however, at levels of exposure considered in the assessment, the Government concluded that it is not harmful to human health or to the environment.

The screening assessment focused on 1-propene, 2-methyl, sulfurized, also referred to as sulfurized isobutylene. It was assessed under the under the third phase of the Chemicals Management Plan (CMP).
Sulfurized isobutylene is a substance of unknown or variable composition, complex reaction products, or biological materials (UVCBs).
Sulfurized isobutylene does not naturally occur in the environment.
According to information gathered by the Government, this substance is mainly used in automotive lubricants and greases in Canada.

Canadians may be exposed to sulfurized isobutylene from the use of products available to consumers (lubricants and greases) and from drinking water, due to industrial releases.
According to the information considered under the ERC Approach, sulfurized isobutylene was identified as having low ecological exposure potential.

To identify health effects information, international reports of data were considered. This included a review by the United States Environmental Protection Agency on alkyl sulfides.
The critical effects identified for characterizing the risk to human health in the screening assessment were decreased bodyweight and blood system effects, following dermal exposure to sulfurized isobutylene.
There were limited health effects data for this substance; therefore, a comparative approach, called read-across, using data available for similar substances was used to assess potential health effects. Developmental effects were identified as a critical effect following long-term oral exposure to sulfurized isobutylene.
According to information considered under the ERC Approach, sulfurized isobutylene was identified as having a low ecological hazard potential.

There are groups of individuals within the Canadian population who, due to greater susceptibility or greater exposure, may be more likely to experience adverse health effects from exposure to substances.
Certain subpopulations are routinely considered throughout the screening 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 health effects. These subpopulations were taken into account in the risk assessment outcomes of sulfurized isobutylene.

Using a comparison of levels at which Canadians may be exposed to sulfurized isobutylene, and levels associated with critical effects, it was determined that the risk to human health is low.
Based upon the outcome of ERC Approach, sulfurized isobutylene is considered unlikely to be causing ecological harm.

The Government concluded that sulfurized isobutylene is not harmful to human health at levels of exposure considered in the assessment, and is not entering the environment at levels that are harmful.

Sulfurized isobutylene may be found in products available to consumers. Canadians should follow any safety warnings and directions related to the product, and dispose of products responsibly.
Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.
The screening assessment for sulfurized isobutylene focused on potential risks of exposure to the general population of Canada, rather than occupational exposure. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System. For information concerning workplace health and safety and what steps to take in the workplace, Canadians should consult their employer or the Occupational Health and Safety Regulator in their jurisdiction.