Under the Canadian Environmental Protection Act, 1999 (CEPA 1999), the risk posed by a substance is determined by considering both its hazardous properties (its potential to cause adverse human health or ecological effects) and the amount of exposure there is to people and the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending upon the level of exposure.
As a result of the draft screening assessment, the Government is proposing that 6 substances in the NSAs Group are not harmful to human health or to the environment at levels of exposure considered in the assessment.
About these substances
The screening assessment focuses on 6 of 7 substances referred to collectively as the Naphthalene Sulfonic Acids and Salts (NSAs) Group under the Chemicals Management Plan (CMP):
Naphthalenesulfonic acid, sodium salt (NaNSA)
Naphthalenesulfonic acid, dinonyl- (DNNSA)
Naphthalenesulfonic acid, dinonyl-, barium salt (BaDNNSA)
Naphthalenesulfonic acid, dinonyl-, calcium salt (CaDNNSA)
Naphthalenedisulfonic acid, dinonyl- (DNNDSA), and
Naphthalenesulfonic acid, bis(1-methylethyl)-, compd. with cyclohexanamine (1:1) (CDINSA).
The 6 substances are commercially produced and do not occur naturally in the environment.
According to information gathered by the Government, in Canada, these substances may be used in fuels, lubricants, oil and natural gas extraction, paints and coatings, rubber materials, and water treatment processes.
Human and ecological exposures
Canadians may be exposed to DNNSA, CaDNNSA and DNNDSA mainly through drinking water.
Canadians may also be exposed to CaDNNSA through the use of a lubricant product available to consumers.
Exposure of Canadians to NaNSA is not expected, and exposure to BaDNNSA and CDINSA is expected to be negligible, based on the results of the Rapid Screening of Substances with Limited General Population Exposure approach.
The ecological exposure of DNNSA, BaDNNSA, CaDNNSA, DNNDSA, and CDINSA was considered as a group, due to the potential for these substances to be used interchangeably in industrial applications.
They have the potential to be released to the aquatic environment during lubricant oil blending, use of metal working fluids, formulation and industrial use of paints and coatings, and formulation of oil and gas products.
They also have the potential to be released to the environment through the application of biosolids to land.
According to the information considered under the ERC Approach, NaNSA was identified as having low ecological exposure potential.
Key health and ecological effects (hazard)
There were limited health effects (hazard) data for DNNSA, CaDNNSA and DNNDSA; therefore, a comparative approach using similar chemicals, called read-across, was used for assessing potential health effects.
Using data available on similar substances, the critical effect for characterizing the risk to human health from exposure to these substances were considered to be effects on the kidneys and thyroid.
The health effects of NaNSA, BaDNNSA, and CDINSA, were not investigated in this screening assessment as Canadians are not expected to be exposed to NaNSA, and exposure to BaDNNSA and CDINSA are considered to be negligible.
According to information considered under the ERC Approach, NaNSA was identified as having a low ecological hazard potential.
The ecological hazard of DNNSA, BaDNNSA, CaDNNSA, DNNDSA, and CDINSA was considered as a group, due to similarities in their chemical structures and ecological effects.These substances were considered as having moderate hazard to aquatic organisms and low hazard to benthic and soil organisms.
Risk assessment outcomes
Considering all information presented, the risk to human health is considered to be low for NaNSA, BaDNNSA and CDINSA.
Based upon a comparison of levels to which Canadians may be exposed to DNNSA, CaDNNSA, and DNNDSA, and the levels associated with health effects, the risk to human health for these substances is considered to be low.
NaNSA is considered unlikely to be causing ecological harm, based upon the outcome of the ERC Approach.
Considering all information presented, it was determined that there is low risk of harm to the environment from DNNSA, BaDNNSA, CaDNNSA, DNNDSA, and CDINSA.
As a result of the draft screening assessment, the Government is proposing that NaNSA, DNNSA, BaDNNSA, CaDNNSA, DNNDSA, and CDINSAare not harmful to human health or to the environment at levels of exposure considered in the assessment.
Some of these substances 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.