a. (5.5 pts.) Hexavalent chromium (or chromium VI) is used in industrial compoun

Question

a. (5.5 pts.) Hexavalent chromium (or chromium VI) is used in industrial compounds found in paints, dyes, and plastics. It is known as a carcinogen through inhalation. Calculate the acceptable dose (concentration) of chromium VI through inhalation assuming a risk of 1 x 10-6 for an adult female breathing in this air her entire lifetime.

b. (1 pt.)   Currently there is no federal standard for chromium VI in drinking water, only for total chromium. How does your calculated concentration value compare to the US EPA’s enforceable drinking water standard (also known as the maximum contaminant level, MCL) for total chromium? You will need to find the MCL for hexavalent chromium, which you can identify the value through a simple internet search.

Explanation / Answer

Risk associated with carcinogenic substance:

Risk = I x SF                       ( for inhalation value of chromium value is 41mg/kg.day-1)

Inhalation value (I)

Slope Factor (SF)

I = risk/SF

1x106 /41 = 0.25 x 106 x 360day/yr x 70rs = 63 x 108

108 it exceed risk limit of 106

According to USEPA's enforceable drinking water stand also known as the maximum contaminant level, MCL for total chromium is 0.1mg/L. The world health organisation (WHO) gudline is 0.05mg/L for total chromium

total chromium present in ground water is more, where as surface water has less value.

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