Abstract
Abstract Clinical events at the Quebec Poison Control Center (QPCC) were reviewed to test the hypothesis that acidity and alkalinity form a legitimate basis for classifying household chemical products. To that end, the effects of cutaneous and oral exposure to 23 cleaning agents were first correlated with product categories based on intended usage, then with pH and titratable acid/alkaline reserve (TAR). Five categories of alkaline products were identified, ranging from non-irritant to irritant to corrosive. In contrast, only one category of acidic products was identified; they were classifed as corrosive. Both cutaneous and oral exposure data support a classification based essentially on alkaline cleaning products. In view of an average skin pH of 4.5-6.0 and the more easily managed acid irritations, to classify all acidic products as mirror images of their basic counterparts, centered around neutral pH, would be conservative but requires further elucidation. Primary irritation of the skin and mucosal lining increased with alkalinity but resulted in caustic injury at the extreme ends of the pH scale or with products containing a defined titratable alkaline reserve (TAR) given a minimum pH of 11.0. This TAR threshold was found to be 10 for solids and 5 for liquids. In addition to consideration of the role of irritation inhibitors, our analysis of the QPCC data led to the following definitions: 1) an alkaline cleaning product is corrosive if its pH is 13.0 or greater, or if 10.5 ≤ pH < 13.0 and the alkali reserve is 10 or greater for solids or 5 or greater for liquids; 2) an alkaline product is an irritant if 12.0 ≤ pH < 13.0 and the alkali reserve is less than 10 for solids or less than 5 for liquids, or if 10.5 ≤ pH < 12.0 and 5 ≤ TAR < 10 for solids or 3 ≤ TAR < 5 for liquids. A recommendation is offered towards possible inclusion of those corrosivity and irritancy criteria in a hazard-based scheme for classifying and labelling household cleaning products.