Natural Science The excess lifetime cancer risk R is a measure of the likelihood that an i...

Natural Science The excess lifetime cancer risk R is a measure of the likelihood that an individual will develop cancer from a particular pollutant. For example, if R = .01, then a person has a 1% increased chance of developing cancer during a lifetime. The value of R for formaldehyde can be calculated from the equation R = kd, where k is a constant and d is the daily dose in parts per million. The constant k for formaldehyde can be calculated from the formula , where B is the total number of cubic meters of air a person breathes in one day and W is a person’s weight in kilograms.†

(a) Find k for a person who breathes in 20 cubic meters of air per day and weighs 75 kg.

---

(b) Mobile homes in Minnesota were found to have a mean daily dose d of .42 parts per million.‡ Calculate R.

---

(c) For every 5000 people, how many cases of cancer could be expected each year from the preceding levels of formaldehyde? Assume an average life expectancy of 72 years.

†A. Hines, T. Ghosh, S. Layalka, and R. Warder, Indoor Air Quality and Control (Upper Saddle River, NJ: Prentice Hall, 1993), (TD 883.I.1476 1993).

‡I. Ritchie and R. Lehnen, “An Analysis of Formaldehyde Concentration in Mobile and Conventional Homes,” Journal of Environmental Health 47:300–305.