New substances: risk assessment summary, new substances notification 19597

Official title: New Substances Notification 19597: Benzenesulfonic acid, branched and linear alkyl derivatives magnesium salts, overbased (Confidential Accession No. 19275-3)

Regulatory decisions

Under the provisions for Substances and Activities New to Canada in Part 5 of the Canadian Environmental Protection Act, 1999 (CEPA), and pursuant to section 83 of the Act, the Minister of the Environment and the Minister of Health have assessed information in respect of the substance and have determined that it is not anticipated to 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, constitute or may constitute a danger to the environment on which life depends, or constitute or may constitute a danger in Canada to human life or health. 

Substance identity

The notified chemical is benzenesulfonic acid, branched and linear alkyl derivatives magnesium salts, overbased (Confidential Accession No. 19275-3), and is considered a substance of unknown or variable composition, complex reaction products or biological materials (UVCB).

Notified and potential uses

The substance is proposed to be imported into Canada in quantities greater than 10 000 kg/yr for the notified use in automotive oils. Potential uses may include use in other automotive or industrial applications.

Environmental fate and behaviour

Based on its physical and chemical properties, if the substance is released to the environment, it will tend to partition to soil and sediment. The substance is expected to be persistent in these compartments based on its very low biodegradability (≤10% over 28 days). The substance is not expected to bioaccumulate based on the low bioconcentration factor (<250 L/kg) of shorter chain length components and the low solubility of longer chain length components which limits bioavailability. 

Ecological assessment

Based on surrogate data on structurally related chemicals, the substance is expected to have low acute toxicity in fish, aquatic invertebrates and algae (median lethal loading rate and median effective loading rate >100 mg/L). The notified substance contains alkyl benzene sulfonate which have been reported to be associated with high chronic toxicity in ecological receptors (5^th percentile hazardous concentration (HC₅), concentration expected to protect 95% of species at the no-observed-effect level). Using the HC₅ for one alkyl benzene sulfonate and by applying an assessment factor of 10 to account for expected toxicity increases between varying alkyl chain lengths, the predicted no-effect concentration (PNEC) was calculated to be in the range of 10-100 µg/L, which was used to estimate the ecological risk. 

The notified and other potential activities in Canada were assessed to estimate the environmental exposure potential of the substance throughout its life cycle. Environmental exposure from the notified activities is expected to be negligible as no water is used during formulation and blending and during the methods used for cleaning of transportation vessels, and any releases from use in automotive oils would be minimal and widely dispersed. For potential activities such as use in metalworking fluids, environmental exposure is expected to be mainly by release of the substance to water resulting in a PEC in the range of 0.1-1 µg/L. For potential activities such as manufacturing, environmental exposure is expected to be negligible.

Based on the low potential for environmental exposure when used as notified, and comparing the PEC for potential activities with the PNEC resulting in a ratio less than 1, the substance is unlikely to cause ecological harm in Canada.

Human health assessment

Based on the available hazard information for the substance and surrogate data on structurally related chemicals, the substance is expected to have a low acute toxicity by the oral and dermal routes (median lethal dose >2000 mg/kg body weight) and moderate subchronic toxicity following repeated oral doses in mammalian test animals (28-day no-observed-adverse-effect level 30-300 mg/kg-bw/day). It is not expected to be a dermal sensitizer (no evidence of sensitization in human repeated insult patch test). It is not mutagenic in vitro or clastogenic in vitro or in vivo. Therefore, the substance is unlikely to cause genetic damage. 

When the notified substance is used in automotive oils industrially or commercially, direct exposure of the general population is not expected due to the industrial/commercial nature of the use. When the notified substance is used in automotive oils available to consumers, direct exposure of the general population is expected to be mainly by contact with the skin at low levels given the low concentration of the substance in end-use products (<1%), and systemic uptake will be limited by its high molecular weight and hydrophobic nature of the substance. In addition, products containing the notified substance will be used infrequently by consumers. Indirect exposure of the general population from environmental media is expected to be at low levels given the low potential for environmental release. Potential uses of the substance include use in oils for other applications, where direct and indirect exposure of the general population would be expected to be low, similar to that of the notified use.

Based on the low to moderate toxicity and low potential for exposure, the substance is not likely to pose a significant health risk to the general population, and is therefore unlikely to be harmful to human health. 

Assessment conclusion

When the substance is used as notified or for other identified potential activities, it is not expected to be harmful to human health or the environment according to the criteria under section 64 of the Act. 

A conclusion under CEPA, on this substance, is not relevant to, nor does it preclude an assessment against the hazard criteria for Workplace Hazardous Materials Information System that are specified in the Controlled Products Regulations or Hazardous Products Regulations for products intended for the workplace.