Thiophosphate Alkyl Esters Group - information sheet

Reaction products of 4-methyl-2-pentanol and diphosphorus pentasulfide, propoxylated, esterified with diphosphorous pentaoxide, and salted by amines, C12-14- tert-alkyl (TPAE-1)

CAS Registry Number 91745-46-9

Phosphorothioic acid, O,O-dibutyl ester, mixed (C8,C16,C18) alkylamine salt (TPAE-2)

Confidential Accession No. 11105-8

Overview

The Government of Canada conducted a science-based evaluation, called a screening assessment under the Canadian Environmental Protection Act, 1999 (CEPA 1999) to address the potential for harm to Canadians and to the environment from 2 substances in the Thiophosphate Alkyl Esters (TPAEs) Group.
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.
As a result of the draft screening assessment, the Government is proposing that TPAE-1 is not harmful to human health at levels of exposure considered in the assessment, but may be harmful to the environment. The Government is also proposing that TPAE-2 is not harmful to human health or to the environment, at levels of exposure considered in the assessment.
The Government published a risk management scope document for TPAE-1 to initiate discussions with stakeholders on the development of risk management options.

About these substances

The screening assessment summarized here focuses on 2 substances referred to collectively as the Thiophosphate Alkyl Esters Group under the Chemicals Management Plan (CMP).
Both substances in this group are unknown or variable composition, complex reaction products, or biological materials (UVCBs). They are composed of multiple components, primarily of alkyl dithiophosphate or thiophosphate anions and aliphatic amine counterions.
TPAE-2 was evaluated in the Final Screening Assessment for the Rapid Screening of Substances with Limited General Population Exposure. The human health exposure potential for this substance was considered to be negligible, and as a result, this substance was found to be of low concern to human health. Therefore, TPAE-2 was not further assessed for human health in this group assessment.
According to information gathered by the Government, these substances are used in Canada in industrial lubricants and lubricant additives. TPAE-1 is also used in metalworking fluids.

Human and ecological exposures

TPAEs have the potential to be released to the environment through discharges from wastewater treatment systems associated with 2 industrial uses: formulation of lubricants and use in metalworking fluids. Such releases are likely to result in exposure to aquatic organisms near points of release.
As a result of these potential industrial releases, Canadians may be exposed to TPAE-1 from drinking water.

Key health and ecological effects (hazard)

The critical effects identified for characterizing the risk to human health for TPAE-1 were effects in the adrenal glands and neurotoxic effects.
Ecotoxicity data for the whole substances and for the aliphatic amine components were used to assess potential ecological hazards. The data indicates that both the (di)thiophosphate alkyl ester and aliphatic amine components of the TPAEs have high long-term toxicity to aquatic organisms, and the aliphatic amines components have moderate to low chronic toxicity to soil organisms.

Risk assessment outcomes

On the basis of the information presented in the draft screening assessment, the risk to human health from the 2 substances in the Thiophosphate Alkyl Esters Group is low at current levels of exposure.
Considering all information presented, it was determined that there is risk of harm to the environment from TPAE-1. TPAE-2 is not expected to pose a risk to the environment at current levels of exposure.
The Government of Canada published the Draft Screening Assessment for the Thiophosphate Alkyl Esters Group on March 13, 2021. The public are invited to comment on this assessment during the 60-day public comment period ending on May 12, 2021.

Proposed screening assessment conclusions

The Government is proposing that the 2 substances in the Thiophosphate Alkyl Esters Group are not harmful to human health at levels of exposure considered in the assessment.
The Government is also proposing that TPAE-1 may be entering the environment at concentrations that are harmful to the environment and that TPAE-2 is not entering the environment at concentrations that are harmful to the environment.
Also, TPAE-1 is proposed to meet the persistence criteria but not the bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.

Preventive actions and reducing risk

The Government of Canada published the Proposed Risk Management Scope for TPAE-1 of the Thiophosphate Alkyl Ester Grouping on March 13, 2021. The public are invited to comment on this document during the 60-day public comment period ending on May 12, 2021.
If the proposed conclusion is confirmed in the final screening assessment, the Government will consider adding TPAE-1 to Schedule 1 of CEPA 1999, also called the List of Toxic Substances. Adding a substance to the list does not restrict its use, manufacture or import. Rather, it enables the Government to take risk management actions under CEPA 1999.
To address ecological concerns, the Government is considering regulatory and non-regulatory options for the metalworking sector, such as environmental release guidelines, codes of practice, pollution prevention planning notices, and regulations to prevent or minimize the release of the TPAE-1 into the aquatic and terrestrial environment.
- Metalworking fluids are oils and other liquids that are used to cool and/or lubricate metal when it is being machined, ground, milled, or manipulated. The metalworking fluid sector is composed of users of metalworking fluids, including facilities that manufacture metal products or machinery, and those that are involved in the rebuilding and/or maintenance of these products.
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 May 12, 2021.
Risk management actions may evolve, based on the conclusions of the final screening assessment, or as a result of risk management actions published for other substances. This is to ensure effective, coordinated, and consistent risk management decision-making.
Information on the risk management of substances addressed under the CMP is available.

Additional considerations

Changes in use patterns for TPAE-2, such as using it as an alternative for chemicals with similar uses or functions, could lead to a higher exposure potential. For this reason, follow-up activities to track changes in exposure or use patterns for TPAE-2 are being considered.
Stakeholders are encouraged to provide any information pertaining to TPAE-2 that may help inform the choice of follow-up activity, during the 60-day public comment period on the assessment. This could include information on new or planned import, manufacture or use of the substance

Related information

The screening assessment for the Thiophosphate Alkyl Esters Group 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 (WHMIS). For information concerning workplace health and safety, Canadians should consult their employer for information on what steps to take in the workplace and/or the Occupational Health and Safety Regulator in their jurisdiction.

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Date modified:: 2021-03-12

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