CHEMICAL PROFILES|Total Hazard Value Scores (IRCH)

The Indiana Clean Manufacturing Technology and Safe Materials Institute (CMTI) at Purdue University has developed a hazard evaluation system for chemicals that produces separate rankings for ecological effects and occupational health effects, as well as a total hazard score that integrates both types of hazards. This system, the Indiana Relative Chemical Hazard Ranking System (formerly known as 3P2M), combines information about a chemical's toxicity to humans and ecosystems with information about chemical characteristics that influence the likelihood of exposure to a substance.

WHAT DO THE SCORES MEAN?
IRCH environmental hazard value scores indicate how a chemical compares with others in terms of its capacity to impact human health, ecosystems, or environmental health generally. The graphic shows where a compound's hazard score falls relative to all chemicals that have been ranked using this system, indicating whether it is more or less hazardous than most chemicals. Chemicals that score at the far right end of the scale are significantly more hazardous (in the worst 10% of all chemicals according to this scoring system).

All chemicals scored by a system have been placed in "bins" defined by percentiles (e.g., a chemical's score is in the least toxic 25% of chemicals scored by a system). The graphic illustrates which bin a chemical falls in according to each scoring system in Scorecard. Looking across these different systems, it is possible to identify chemicals that consistently score as high or low hazards, as well as chemicals that score high on some measures (such as human health hazards) but low on others (such as ecological hazards).

STRENGTHS AND WEAKNESSES OF THIS TYPE OF SCORING SYSTEM?
IRCH total hazard value scores are based on toxicity and exposure considerations. Moreover, IRCH total scores are the only scores that integrate concerns about ecological and (occupational) human health impacts into a combined score. This ensures that chemicals that pose low human health hazards, for example, remain priorities if they pose high ecological hazards.