New substances: risk assessment summary, new substances notification 20475
Official title: New Substances Notification 20475: Hexanedioic acid cycloalkyl alkylhexyl ester (Confidential Accession Number 19582-0)
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 hexanedioic acid cycloalkylalkylhexyl ester (Confidential Accession Number 19582-0).
Notified and potential uses
The substance is proposed to be manufactured in Canada in quantities greater than 10 000 kg/yr for the notified use as an additive in caulks, sealants and plastics. Potential uses may include uses as an additive in industrial oils, lubricants, hydraulic fluids, adhesives, and cosmetics.
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 sediments. The substance is not expected to be persistent in this compartment based on high ready biodegradability (60 to 85% over 28 days). The substance is not expected to bioaccumulate based on its low expected bioconcentration factor (< 250 L/kg).
Environmental risk assessment
Based on the available hazard information, the substance is expected to have low acute toxicity to fish (no adverse effects observed in saturated solutions), high acute toxicity to aquatic invertebrate (median effective concentration [EC50] for one analogue substance < 1mg/L), low to high chronic toxicity to aquatic invertebrate (maximum acceptable toxicant concentration [MATC] = 0.01 to 0.1 mg/L; lowest-observed-effect-loading-rate > 10 mg/L), and low chronic toxicity to algae (EC50 > 10 mg/L). Using the MATC from the most sensitive organism (aquatic invertebrates) and by applying an assessment factor of 2 to account for species sensitivity variation, the predicted no-effect concentration (PNEC) was calculated to be in the range of 0.01 to 0.1 mg/L, which was used to estimate the risk to the environment.
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 activity is expected to be mainly from manufacturing and cleaning of transportation vessels resulting in predicted environmental concentrations (PECs) in the range of 0.001 to 0.01 mg/L. For potential activities such as manufacturing in a different facility, environmental exposure is expected to be mainly from the release of the substance to water resulting in a PEC in the range of 0.01 to 0.1 mg/L, with the exact value being below the PNEC.
Comparing the PEC with the PNEC, the ratio is less than 1. This, along with other lines of evidence including environmental fate, hazard, and exposure, indicates that the substance is unlikely to cause harm to the environment in Canada.
Human health assessment
Based on the available hazard information, the substance has a low acute toxicity by the oral route (median lethal dose (LD50) > 300 to 2000 mg/kg body weight, with no toxicity observed at the highest dose). It is expected to have a low acute toxicity by the dermal route (LD50 > 2000 mg/kg body weight) and by inhalation (median lethal concentration > 5 mg/L/4hr). It is expected to have moderate subchronic toxicity following repeated oral doses in mammalian test animals (28-day no-observed-adverse-effect level (NOAEL) 30 to 300 mg/kg-bw/day). The substance is expected to have moderate developmental toxicity (NOAEL 30 to 300 mg/kg-bw/day) and low reproductive toxicity (NOAEL > 1000 mg/kg-bw/day) following repeated oral doses in mammalian test animals. It is not expected to be a dermal sensitizer (0% response in a guinea pig maximization test). It is not mutagenic in vitro and is not expected to be clastogenic in vitro or in vivo. Therefore, the substance is unlikely to cause genetic damage.
When the notified substance is used as an additive in caulk and sealants, consumers may come into contact with end-use products containing the substance. However, direct exposure is limited because the substance is expected to be tightly bound to the polymer matrix and will be unavailable for uptake. Indirect exposure of the general population from environmental media such as drinking water is conservatively estimated to be at levels in the range of 0.1 to 1 µg/kg bw/day for children and adults.
Potential uses of the substance include uses as an additive in industrial or commercial oils, lubricants, hydraulic fluids, and plastics, where significant direct exposure of the general population is not expected. Other potential uses of the substance include cosmetics, where direct exposure of the general population is expected to be mainly by contact with the skin resulting in a chronic internal dose estimated to range from 0.1 to 10 μg /kg-bw/day for adults. No cosmetics intended for use in children containing the notified substance were identified. Indirect exposure of the general population from environmental media and food is estimated to be at levels in the range of 0.2 to 200 μg/kg-bw/day and mainly by ingestion.
The target margin of exposure (MOET) was calculated to be 100 based on the available information for a similar substance. The MOET is the level of exposure at or above which there is no expected risk in the exposed population. The derived margin of exposure (MOED) is the ratio of the point of departure value to the available exposure doses and is compared to the MOET. As the MOED is higher than the MOET for all estimated human exposures, 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.
The assumptions made in the assessment are considered to be adequately protective for the general population as well as for subpopulations who may be more susceptible or highly exposed.
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 the Hazardous Products Regulations for products intended for the workplace.