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 worker exposure hazard scores indicate how a chemical compares with others in terms of its capacity to impact the health of a factory worker. 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?
The IRCH environmental hazard scores are based on toxicity and exposure potential considerations, and therefore provide a better comparison of chemical hazards than systems such as the UTN human health effects scores, which only include toxicity measures. One important limitation of the IRCH system is that exposure potential is estimated based on the values of certain physical and chemical properties of the chemical, not on estimates of the actual dose received as in EDF's Toxic Equivalency Potentials. Another important limitation is that the IRCH health scores are designed for occupational exposures to chemicals, which are generally much higher than environmental exposures experienced by the general public.
WORKER EXPOSURE HAZARD SCORE (IRCH) FOR 3,3'-DIMETHOXYBENZIDINE DIHYDROCHLORIDE
Worker Exposure Hazard Score (IRCH) = 18
TECHNICAL DETAILS ON HOW SCORES ARE DERIVED
The IRCH system assigns worker exposure hazard scores between 0 and 50 based on the
Worker Exposure Hazard = (HVhealth x HVexposure) + (2 x HVsafety)
- HVhealth = health effects hazard score, based on chronic and acute occupational toxicity measures
- HVexposure = routes of exposure hazard value, based on chemical properties that indicate how exposure will occur (e.g. can the chemical be ingested, what is the ability of the chemical to form dusts or mists, etc.)
- HVsafety = safety hazard value which considers a chemical's flammability, reactivity, and corrosivity
The IRCH system is the only ranking methods in Scorecard that explicitly looks at occupational hazards. EDF was unable to extend the IRCH system to additional chemicals because the Scorecard lacks some of data elements that are required by
IRCH: Indiana Relative Chemical Hazard Score. Indiana Clean Manufacturing Technology and Safe Materials Institute.
Values from Indiana Relative Chemical Hazard Score - CAS Order (Updated 5/22/02)