The Government of Canada conducted a science-based evaluation, called a screening assessment, to address the potential for harm to Canadians and to the environment from substances in the Ketones Group.
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 this screening assessment, the Government is proposing that MEK, MIBK, and 2,4-PD are harmful to human health, but not harmful to the environment. MPK, MIAK, DAA, diacetyl, 2,3-PD, acetoin, and MO are not proposed to be harmful to human health or the environment. Although some of these substances may be associated with health effects, the risk to human health is considered to be low at current levels of exposure.
About these substances
This screening assessment focuses on 10 substances referred to collectively as the Ketones Group, under the Chemicals Management Plan (CMP). The substances addressed are methyl ethyl ketone (MEK), methyl propyl ketone (MPK), methyl isobutyl ketone (MIBK), methyl isoamyl ketone (MIAK), diacetone alcohol (DAA), diacetyl, 2,3-pentanedione (2,3-PD), acetoin, 2,4-pentanedione (2,4-PD), and mesityl oxide (MO).
The Government gathers information on substances, including details on their commercial status in Canada, to support risk assessment and risk management of substances under the CMP.
All 10 substances in this group are commercially produced (man-made) and are also naturally present in the environment in various plants and/or foods, or by being produced by microbes and other organisms. MEK, diacetyl and acetoin are also naturally produced in humans and MEK is an approved food additive.
In general, substances in the Ketones Group are primarily used as solvents in various products, including products available to consumers such as paints, coatings, and adhesives. They may also be used as food flavouring agents, in cosmetics, and as formulants in pest control products. These substances may be used in numerous industrial applications.
Human and ecological exposures
Canadians may be exposed to MEK and MPK from air and food (primarily due to their natural occurrence), and also from products available to consumers, including cosmetics, paints and do-it-yourself (DIY) products for MEK, and paint products for MPK.
Exposure to MIBK, MIAK, and DAA may occur from the environment and food (primarily from their natural occurrence) and from the use of products available to consumers, including cosmetics, markers, paints and other DIY products.
Canadians may be exposed to diacetyl, 2,3-PD, and acetoin from food (due to their natural occurrence and use as flavouring agents), and to diacetyl and 2,3-PD, from the use of products available to consumers, including cosmetics and air fresheners, respectively.
Exposure of Canadians to 2,4-PD may occur from its natural occurrence in food and from the use of a limited number of products available to consumers, such as specialty coating products. Exposures to MO may occur from its presence in air and food.
Eight substances in this group were identified according to information considered under the Ecological Risk Classification of Organic Substances Approach as having low ecological exposure potential. MEK and DAA were identified as having high exposure potential due to high reported use quantities in combination with a long half-life (time to decrease in concentration by half) in air.
There were some limitations to the health effects data available for some substances in this group. Therefore, a comparative approach using similar chemicals, called read-across, was used for assessing potential health effects for these substances with limited data.
Important or "critical" health effects included developmental effects for MEK and decreased body weight gain for both MEK and MPK.
The International Agency for Research on Cancer (IARC) has classified MIBK as "possibly carcinogenic to humans". Effects on the liver and kidney, as well as developmental effects, were also considered to be critical effects considered in this risk assessment. These critical effects were also used to characterize risk for MIAK and DAA.
Critical effects considered in the assessment for diacetyl, 2,3-PD, and acetoin were effects on the respiratory tract.
Using available health effects information, critical effects for the assessment of each 2,4-PD and MO were general systemic effects, as well as developmental effects for 2,4-PD.
According to information considered under the Ecological Risk Classification of Organic Substances Approach, all 10 substances in this group were identified as having low ecological hazard potential.
Risk assessment outcomes
Based upon a comparison of levels to which Canadians may be exposed to MEK from some products available to consumers, namely lacquer and adhesive remover, paint products, and PVC cement/primer, and levels associated with critical health effects it was determined that this substance may pose a risk to human health.
Similar comparisons of exposure to MIBK from the use of various paint and wood lacquer products, and levels associated with critical health effects determined that this substance may pose a risk to human health.
Also, a comparison of levels to which Canadians may be exposed to 2,4-PD from the use of a coating applied to a large surface area, such as a trailer or boat, and levels associated with critical health effects, determined that this substance may pose a risk to human health.
Comparisons of exposures to MPK, MIAK, DAA, diacetyl, 2,3-PD, acetoin, and MO, and levels associated with health effects, determined that the risk to human health from each of these 7 substances is low.
The Ecological Risk Classification of Organic Substances Approach characterized the 10 substances in this group as posing a low risk of harm to the environment.
MEK and 2,4-PD are proposed to meet the persistence criteria but not the bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.
MIBK is proposed to not meet the persistence or bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.
As a result of this screening assessment, the Government is proposing that MEK, MIBK, and 2,4-PD are harmful to human health. It is also proposed that MPK, MIAK, DAA, diacetyl, 2,3-PD, acetoin, and MO are not harmful to human health at current levels of exposure.
The Government is also proposing that none of the 10 substances in the Ketones Group are entering the environment at concentrations that are harmful to the environment.
If the proposed conclusion is confirmed in the final screening assessment, the Government is considering the following actions to address the human health concerns associated with MEK, MIBK, and 2,4-PD:
Adding MEK, MIBK, and 2,4-PD to Schedule 1 of CEPA 1999, also called the List of Toxic Substances; and
Developing regulatory or non-regulatory measures to help reduce exposure to MEK, MIBK, and 2,4-PD in certain products available to consumers.
Also, the Government is seeking further information 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 March 20, 2019.
These substances may be found in products available to consumers. Canadians should follow any safety warnings and directions on product labels and dispose of products responsibly.
Visit Healthy Home for more information on chemical safety in and around the home.
Canadians who may be exposed to these substances in the workplace should consult with their employer and an occupational health and safety (OHS) representative about safe handling practices, applicable laws, and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).
