Example for Benzene

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These indicators assume exposure occurs at the same level, 24 hours per day, for 70 years. This is rarely
true for any single individual, but using a standard set of assumptions allows us to provide a relative
ranking for known and suspected carcinogens across different exposure routes. We also use cancer
potency factors in the ranking, and these represent the upper bound estimate of carcinogenicity - in
other words, a worst case scenario.

When potential lifetime excess cancer risk is larger than 1 per million, additional study may be
warranted (?).

                           BENZENE                                      DATA QUALITY     DAT A & MAPS
                         (link to profile info)

                                                                        OUTDOOR AIR
                                                                                         Link to Data
                                                                                         Link to Maps
                                                                                         Link to Tables


                                                                         INDOOR AIR

                                                                                         Link to Data


                                                                        INDOOR DUST




                                                                      DRINKING WATER

                                                                                         Link to Data



                                                                          FOOD &
                                                                         BEVERAGES
                                                                                         Link to Data

            (LINKS ON EACH LEGEND ENTRY TO EXPLANATIONS)




HOW DOES BENZENE COMPARE TO OTHER SUBSTANCES?

Link to outdoor air   Link to indoor air          Link to dust    Link to drinking     Link to food
summary graph         summary graph               summary graph   water summary        summary graph
                                                                  graph
LINKS



Standard Assumptions

        Lifestage weights, intakes

        Food list, consumption rates



Cancer Potency Factors

Cancer potency factors are often based on results from laboratory studies using animals. The study
animals are divided into groups based on dose received, and the number of cancers in each group is
observed. When a linear relationship is observed (the number of cancers increase in direct proportion to
the dose), it is possible to predict the number of cancers expected for any given dose.

We do not know how well results from animal studies apply to humans, and often the doses used in
animal studies are much higher than the levels people encounter in real life. Also,

Different agencies may not interpret the animal study results in the same way, and so there can be
more than one cancer potency factor for any particular substance.
BENZENE

        Profile info with additional details on sources and additional links

Legend entries

CAOEHHA: The California Office of Environmental Health Hazard Assement develops cancer potency
    factors.....link to their pages

Health Canada: Health Canada develops cancer potency factors....

US EPA: The United States Environmental Protection Agency develops cancer potency factors.... link to
     IRIS

Data Gap: There are no publicly available databases providing actual measured concentrations, and no
      studies in peer-reviewed published studies were found.

Not Applicable: Exposure is not expected due to the physical properties of the substance, or there is no
     evidence of carcinogenicity via this exposure route.

DATA QUALITY


  OUTDOOR AIR       BENZENE IS MEASURED IN OUTDOOR AIR AT xx MONITORING
                     STATIONS USING ACCEPTED PROTOCOLS
                    BENZENE CONCENTRATIONS VARY FROM PLACE TO PLACE
                    etc



   INDOOR AIR
                    BENZENE IS NOT REGULARLY MEASURED IN INDOOR ENVIRONMENTS.
                     WE DO NOT HAVE MUCH DATA.
                    etc




  INDOOR DUST
                    BENZENE IS NOT EXPECTED TO BE PRESENT IN DUST




DRINKING WATER      BENZENE IS RARELY DETECTED IN DRINKING WATER
                    IF BENZENE WAS PRESENT AT THE MEASUREMENT DETECTION LIMIT
                     (0.05 UG/L), ESTIMATED POTENTIAL EXCESS LIFETIME RISK IS LESS
                     THAN 1 PER MILLION
                    etc


   FOOD & BEV       BENZENE IS NOT REGULARLY MEASURED IN FOODS AND BEVERAGES
                    THE POTENTIAL FOR EXCESS LIFETIME CANCER RISK IS ABOVE
                     1:MILLION DUE TO OLDER DATA SHOWING THE PRESENCE OF BENZENE
                     IN SOME SOFT DRINKS CONTAINING BENZOATE. MANY SOFT DRINKS
                     NO LONGER CONTAIN BENZOATE.
                    etc
Link to Outdoor Air Summary Graph
Link to Indoor Air Summary Graph
Link to Drinking Water Summary Graph
Food and Beverages

				
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posted:12/19/2011
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