Cumulative Risk Index

The cumulative risk index (CRI), also referred to as the aggregate risk index (ARI) has been suggested by the US-EPA (Whalan and Pettigrew 1997) to combine MOEs for chemicals with different AFs. The risk index (RI) of a chemical is the MOE divided by the AF or simply the reference dose divided by exposure, and is the reciprocal of the HQ  

Expi/RfDi + Expii/RfDii + Expin/RfOm + Expiv/RfDiv 

The CRI has the same disadvantages as described for the HI and in addition, since it is derived from the MOE approach, the CRI is not as transparent and understandable as the HI. It also involves more complex calculations. 

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The approaches discussed are the hazard index (HI) (Section 10.5.1.1) and the weight-of-evidence (WOE) modification to the HI (Section 10.5.1.2), the point of departure index (PODl) (Section 10.5.1.3), toxicity equivalency factors (TEFs) (Section 10.5.1.4), the margin of exposure (MOE) procedures (Section 10.5.1.5), and the cumulative risk index (CRl) method (Section 10.5.1.6). 

CUMULATIVE CROSS INDEX TO lARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC RISKS TO HUMANS... 

A hazard index of <1.0 represents an acceptable cumulative risk for all contaminants and routes of exposure. In other words, if the hazard index is < 1.0, the receptors are exposed to concentrations that do not present a hazard because detoxification and other mechanisms forestall toxic effects that could result from exposure to the contaminant. The quantitative value obtained for the HI is not a value of risk it does not indicate the probabihty of harm as the result of exposure. 

IARC. 1996. Cumulative cross index to IARC Monograph on the evaluation of carcinogenic risks to humans. International Agency for Research on Cancer. 66 487-514. 

The cumulative risk assessment guidance document (EPA, 2002) states that the index chemical should be selected based on the availability of high-quality... 

LifeLine Group (2005) Aggregate and Cumulative Exposure and Risk Assessment Software, Version 4.3. Annandale, VA, The LifeLine Group, Inc. (http // www.thelifelinegroup.org/index.htm software accessed 5 May 2005). 

There are two risk factors a high total cumulative deferoxamine dose and a low serum ferritin concentration. In order to prevent deferoxamine ototoxicity, a therapeutic index has been proposed, defined as the daily dose of deferoxamine (in mg/kg/day) divided by the serum ferritin concentration (ng/ml) (SED-12, 552) (68). A therapeutic index of 0.027 is considered to be associated with a low risk of deterioration of hearing. Regular audiometric follow-up, with special attention to the frequencies of 3 and 6 kHz, can help to detect and prevent permanent hearing loss. 

Eisler, R. Handbook of chemical risk assessment health hazards to humans, plants, and animals, metalloids, radiation, cumulative index to chemicals and species, vol. 3, chapter 28, CRC Press, Boca Raton (FL) 2000. 

In summary, the above studies show that neurobehavioral evaluation of pesticide workers reveal increased prevalence of neurologic symptoms and changes in neurobehavioral performance indicative of mild cognitive and psychomotor dysfunction. These effects appear to be more prevalent during the period of exposure, but also persist beyond the period of exposure. Total cumulative exposure seems to be a greater risk factor for poor performance than any other covariant. Deficits in visuomotor speed as indexed by the digit symbol substimtion test and the trailmaking tests have been shown to be consistently effected as well as tests of selective attention and memory... 

EPA used the relative potency factor (RPF) method in its cumulative hazard assessment of the OPs. The RPF method is based on the assumption of dose additivity, Dose additivity is the agency s assumption when evaluating the joint risk of chemicals that are toxicologically similar and act at the. same target site (EPA, 2001c). Briefly, with the RPF approach, the toxic potency of each chemical is first determined. One chemical, called the index chemical, is then selected. The index chemical provides the basis for comparison. Relative potency is determined by converting the toxic potency of each chemical into toxic equivalents of the index chemical. 

Eisler, R. 2000. Arsenic. Pages 1501-1566 in Handbook of Chemical Risk Assessment Health Hamrds to Humans, Plants, and Animals. Volume 3. Metalloids, Radiation, Cumulative Index to Chemicals and Species. Lewis Publishers, Boca Raton, Florida. 

Capital indexation. Capital-indexed bonds have been issued in the United States, Australia, Canada, New Zealand, and the United Kingdom. Their coupon rates are specified in real terms, meaning that the coupon paid guarantees the real amount. For example, if the coupon is stated as 2 percent, what the buyer really gets is 2 percent after adjustment for inflation. Each period, this rate is applied to the inflation-adjusted principal amount to produce the coupon payment amount. At maturity, the principal repayment is the product of the bond s nominal value times the cumulative change in the index since issuance. Compared with interest-indexed bonds of similar maturity, these bonds have longer durations and lower reinvestment risk. 

Abbreviations ALAD, delta-aminolevulinic acid dehydratase CBLI, cumulative blood lead index HR, hazard ratio NHANES, National Health and Nutrition Examination Survey (II = second survey, HI = third survey) OR, odds ratio OSHA, Occupational Safety and Health Administration PLEA, petrol-lead emission area RR, relative risk SE, standard error, SIR, standardized incidence ratio SMR, standardized mortality ratio. 

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