To assign a health hazard score to a product, GoodGuide counts the number of its ingredients that are categorized as low, medium or high concern. Ingredients are placed into these categories based on their number of recognized and suspected health effects, their relative toxic potency, whether they are frequently detected in humans, and whether the basic toxicity testing needed to assess chemical safety has been conducted.

Rating: 10 out of 10

Characterizing potential human health impacts requires complete information about the specific ingredients in a product. However, there is no current regulatory requirement that companies disclose full ingredients lists for household chemical products (in contrast with personal care products, where disclosure is required). To create an incentive for disclosure, GoodGuide caps a product’s score if it lacks complete ingredient data or lists generic names that do not support chemical-specific evaluations.

Rating: 10 out of 10

Human health impact scores are adjusted lower if a product includes ingredients that are considered "bad actors," such as chemicals that have been banned by regulatory agencies or targeted for phase out, or if its production process utilizes hazardous chemicals or introduces contaminants to the product.

Rating: 8.0 out of 10