Question

Question #1 (from Mihelcic).

Assume an adult female who weighs 50 kg drinks 2 L of water every day and the absorption factor for the chemical of concern is 75 percent. The concentration of the chemical in the drinking water is 55 ppb. Determine the dose in mg/kg-day.

Question #2 (from Mihelcic).

Determine if exposure by oral ingestion to the chemicals xylene, toluene, arsenic, and hexavalent chromium poses a noncarcinogenic health risk. The chemical-specific reference doses (mg/kg-day) obtained from IRIS are xylene (0.2), toluene (0.8), arsenic (0.0003), and hexavalent chromium (0.003). Assume a 70 kg individual consumes 2 L of water per day with these chemicals dissolved at a concentration of 1 mg/L.

Question #3 (from Mihelcic).

Is there an unsafe risk associated with eating 15 g of fish every day that contains 9.8µg/kg of Arochlor 1254. Arochlor 1254 can exhibit noncarcinogenic effects in humans. Use the IRIS database to find any other information required to solve this problem.

Answer 1

Ans.1) Concentration of the chemical of concern is 55ppb or 0.055 mg/L. So, chemical contains in 2L drinking water 0.11mg. Now, 75% of this 0.11mg is get absorbed i.e. 0.0825mg. 50 kg woman so, absorption per kg body weight is (0.0825/50)= 0.00165mg/kg-day. or this is the daily dose.

Ans. 2) All concerned chemicals are at concentration of 1mg/L. 70kg individual takes 2L water everyday. Daily total intake of each chemical is 2mg.

Now, let's calculate as per kg of body weight.

Xylene-0.02mg/kg-day

Toluene-0.02mg/kg-day

Arsenic-0.02mg/kg-day

hexavalent chromium-0.02mg/kg-day.

Now as per given reference doses arsenic and hexavalent chromium is being taken at a dose sufficient to pose noncarcinogenic health risk.

Q3) From IRIS database reference dose of Arochlor 1254 is 2×10^-5. But body weight of person who is eating not given in question, so I have assumed 70kg.

In 15 g fish chemical present 0.147ug. And for that person concentration is 2.1×10^-6, which is lesser than rfd. So, in this said condition no risk is there.