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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.

TOTAL HAZARD VALUE SCORE (IRCH) FOR SODIUM HYPOCHLORITE

Total Hazard Value Score (IRCH) = 17

TECHNICAL DETAILS ON HOW SCORES ARE DERIVED
The IRCH system assigns hazard scores between 0 and 200 based on the following algorithm:

Total Hazard Value = [(1.15 x Worker Exposure Hazard Value) + (Environmental Hazard Value/3.5)]/2

The components of the total hazard value include a wide variety of measures relating to a chemical's toxicity and physical-chemical properties such as vapor pressure, tendency to bioaccumulate, corrosivity, and so on.

EDF was unable to extend the IRCH system to additional chemicals because the Scorecard lacks some of data elements that are required by this system.

REFERENCE
IRCH: Indiana Relative Chemical Hazard Score. Indiana Clean Manufacturing Technology and Safe Materials Institute.
http://www.ecn.purdue.edu/CMTI/Pollution_Prevention_Progress_Measurement_Method/
Values from Indiana Relative Chemical Hazard Score - CAS Order (Updated 5/22/02)