Canada Releases Updated Science Approach Document (SciAD) for Substances with Low Human Health Hazard Potential
Health Canada recently revised its Science Approach Document (SciAD) for Substances with Low Human Health Hazard Potential. This represents an updating of the original approach document, released in December 2017, in response to feedback received on it.
14 Priority Substances
With the updated SciAD, the goal is to outline the low hazard approach and discuss how it applies to 14 representative priority substances. From the approximately 23,000 substances initially on the Domestic Substances List (DSL), roughly 4,300 were recognized for assessment. Under the Government of Canada's Chemicals Management Plan (CMP), 1,550 still need to be addressed. The 14 substances were selected from among this smaller subset.
| CAS Number | Domestic Substances List Name |
|---|---|
| 409-21-2 | Silicon carbide |
| 1310-58-3 | Potassium hydroxide |
| 1310-73-2 | Sodium hydroxide |
| 1312-76-1 | Silicic acid, potassium salt |
| 1314-56-3 | Phosphorus oxide |
| 1344-09-8 | Silicic acid, sodium salt |
| 7631-90-5 | Sulfurous acid, monosodium salt |
| 7647-01-0 | Hydrochloric acid |
| 7664-38-2 | Phosphoric acid |
| 7664-93-9 | Sulfuric acid |
| 7681-57-4 | Disulfurous acid, disodium salt |
| 7722-84-1 | Hydrogen peroxide |
| 7789-20-0 | Deuterium oxide |
| 12136-45-7 | Potassium oxide |
Results of the evaluation of these chemicals, under the Canadian Environmental Protection Act (CEPA), will be published at a later time.
About the Approach
The hazard-based approach presented within the updated SciAD aims to identify substances of low concern for human health. Under this approach, when toxicological data show that negative health effects are unlikely to occur up to the established 1,000 mg/kg-bw/day Limit Doses, the substances are deemed to be of low concern in terms of human health. A low human health hazard potential is also considered when health effects are limited to localized effects above 100 mg/kg-bw/day. For the purposes of this approach, negative health effects include those that may cause pathological lesions or functional impairment affecting lifespan or the ability to reproduce.
Key steps for evaluating whether a chemical substance is suitable for the low human health hazard potential approach, as noted in the revised SciAD, are shown below:
- Does the substance cause any health effect up to 1,000 mg/kg-bw/day?
- If NO, then the substance may be considered a low concern for human health.
- If YES (or if UNKNOWN), then consider the next decision point.
- Does the substance cause serious effects between 100 and 1,000 mg/kg-bw/day?
- If NO, then the substance may be considered a low concern for human health.
- If YES (or if UNKNOWN), then use of the hazard-based approach is not suitable, and an alternative may be necessary.
Accessing Additional Information
With the publication of this updated approach, it should improve the effectiveness of addressing chemical substances of lower concern. More detailed information on the approach can be found within the revised SciAD.
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