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Exercise 5

Exercise 5. Rem-610 March 3, 2010. Question 1. Use the IRIS Data base of the US‐EPA (http://www.epa.gov/iris) to find the Oral Reference Dose for cadmium consumed in food. Briefly, explain how the oral reference dose was developed. Oral RFD = 1E-3 mg/kg/day (EPA IRIS) or 1 ug /kg/day

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Exercise 5

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  1. Exercise 5 Rem-610 March 3, 2010

  2. Question 1 • Use the IRIS Data base of the US‐EPA (http://www.epa.gov/iris) to find the Oral Reference Dose for cadmium consumed in food. Briefly, explain how the oral reference dose was developed. • Oral RFD = 1E-3 mg/kg/day (EPA IRIS) or 1 ug/kg/day • NOAEL = 1E-2 mg/kg/dayfrom “human studies involving chronic exposures” (US EPA 1984) • / 10x Uncertainty Factor

  3. Question 2 • Calculate the Hazard Index hazard associated with the consumption of 2 oysters per day by an adult of 70 kg. The average wet weight of an oyster is 45 g. Formulate a brief statement about the significance of your finding to an individual with this consumption behaviour. • 3-4 ug/g wet weight Cd in oysters (CFIA) • Average w.w. per oyster = 45 g • Consumption of 2 oysters/day = 270-360 ug/day • For 70kg individual, (270 to 360)/70 = 3.85 to 5.14 ug/kg/day • HI = exposure/RfD = 3.85/1 to 5.14/1

  4. Question 3a • Explore the relationship between the Hazard Index and the rate of oyster consumption per day.

  5. Question 3b • Recommend a human health advisory for the consumption of oysters for oyster consumers. • RfD = 1 ug/kg/day • For 70kg individual, 70 ug/day • 1x45 g oyster ~ 180 ug/day (assuming 4 ug/g ww) • (70 ug/day) / (180 ug/day/oyster) ≤ .399 oysters/day • =< 2.72 oysters/week

  6. Question 4 • Considering that the mean lifetime exposure to Cadmium in Canada from all foods (excluding shellfish) is 13.8 ug/person/day (Dabeka et al. 1987), would your answer to question 3 change? What would be your human health advisory for the consumption of oysters considering the background exposure of the Canadian population to cadmium. • (70 ug/day)/(180+13.8 ug/day) ≤ .36 oysters/day • ≤ 2.53 oysters/week

  7. Question 5 • Recommend a maximum acceptable limit for Cadmium concentrations in oysters aimed for the Canadian market. What are some of the difficulties associated with this approach. • (? ug/g-ww) * (2 oysters/day) * (45 g-ww/oyster) ≤ 70 ug/day – 13.8 ug/day (background) • (? ug/g-ww) ≤ .62 ug/g-ww

  8. Question 6 • Are oyster containing cadmium concentrations less than the limit you arrived at in question 5 safe to eat? Explain why?

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