The Canadian government has confirmed its conclusion that four thiols, three of which are used as food flavouring agents, are not harmful.
The conclusion of the final screening assessment, dated 20 October, makes further regulatory action against the substances under the country's Chemicals Management Plan (CMP) extremely unlikely.
The four substances are:
- dimethyl sulfide;
- benzyl disulfide;
- tert-dodecyl mercaptan; and
- grapefruit mercaptan.
Dimethyl sulfide, benzyl disulfide and grapefruit mercaptan are used as food flavouring agents. Dimethyl sulfide is also used as an odourant in natural gas.
The other substance, tert-dodecyl mercaptan, is used in the manufacture of food packaging materials. It may also be present as an impurity in a range of products available to consumers, including: paints and coatings; vinyl floor coverings; paper products; and various materials made of plastic, rubber or metal.
The assessment of the environmental hazard potential of the substances varied from low for dimethyl sulfide to high for grapefruit mercaptan, via moderate for the other two substances.
With the exception of dimethyl sulfide, all the substances had the potential to cause adverse effects in the aquatic environment and bioaccumulate.
However, the assessment found that the exposure for all four substances was low, resulting in low risk to the environment.
The risk to human health was also low. Thus, the assessment concludes that the substances meet none of the criteria in section 64 of the Canadian Environmental Protection Act (Cepa).