Mixtures of substances in workplaces :
a utility program for evaluating the toxic risk.

A project of the University of Montreal in collaboration with the IRSST

Université de Montréal : Adolf Vyskocil, Claude Viau, Robert Tardif, Michel Gérin, Jules Brodeur
IRSST : Daniel Drolet, François Lemay, Ginette Truchon, Marc Baril
CSST : Gilles Lapointe

Presentation

Mixed exposures to chemical substances are common in workplaces. The Québec regulation, as in the approach of the American Conference of Governmental Industrial Hygienists (ACGIH), stipulates that when two or more substances are present and have similar effects on the same organ of the human body, these effects are considered additive unless established otherwise. For 668 regulated substances in the Regulation respecting the quality of the work environment (RQWE 1994, which became the Regulation respecting occupational health and safety in 2001), we have developed an Access database that contains the health effects, target organs, action mechanisms and toxicokinetic characteristics. In total, eighty-three biological effects have been identified and grouped into 32 classes of similar effects.

This utility operating with the Internet Explorer browser (version 4 or more recent) and developed in JavaScript language allows up to 10 substances in the RQWE to be intersected. Groups of substances with similar effects can then be identified and a mixed exposure index (Rm) can be calculated.

Disclaimer

The purpose of this tool is to facilitate the decision-making of occupational health and safety professionals (physicians, hygienists, inspectors). Presented in a user-friendly format, it contains pertinent information on the potential additive effects of chemical substances found in the workplace. In no case should this tool replace enlightened professional judgement on a specific situation. We mainly want to draw the user's attention to the problem of carcinogens and sensitizers. In the first case, there is a principle called "ALARA" by which exposure to carcinogens should be maintained at the lowest value possible, even when their concentration in the air is below the permissible exposure values in the Regulation. Calculation of the Rm then enables you to identify the extent of the exposure, but even a value below unity does not exempt you from having to reduce this exposure to the lowest possible. With sensitizers, the specificity of the immune reactions is such that additivity of effects is not always observed. This utility is not a final version. We hope that by providing free access to it, users will send us their comments at the following address:
adolf.vyskocil@umontreal.ca

To consult the utility (french version only), click here.