This assignment is based on the case of trichloroethylene exposure in Woburn, MA. The case is the subject of an excellent book by Jonathan Harr called A Civil Action, and a so-so movie of the same name.

Two of the wells in the town of Woburn were contaminated with trichloroethylene (TCE), an industrial solvent that I know some of you are familiar with in other contexts. Several of the children exposed to the water developed leukemia and sued the companies that operated facilities where the chemical was used. In this assignment, we will use Monte Carlo analysis to characterize the risk to the exposed children.

The three principal routes of exposure are:

Water ingestion

Inhalation of ambient air

Inhalation of TCE that evaporates from shower water

Use the data in the table below to respond to the following..

1. Calculate the average daily dose (ADD) and risk for each route of exposure based on average values.

2. Do a run with Crystal Ball (which is an free excel extension). Based on the results of the run, state the upper and lower 95% confidence limits for each of the risks. Determine the parameters that have the greatest influence on the results. Make sure you define the assumption for each uncertain parameter based on the data in the table prior to running Crystal Ball. .

3. Write a brief essay (no more than a page) explaining your results to a lay person.

Parameter	Average	Units	Distribution
TCE concentration in water	225	ug/L	Uniform 183 - 267 ug/L
Water intake	0.87	L/day	Normal Mean: 0.87 L/day 95th percentile: 2 L/day
TCE concentration in ambient air	0.86	ug/m3	Uniform 0.51 - 1.22 ug/m3
Breathing rate	13.1	m3/day	Normal Mean: 13.1 m3/day 95th percentile: 19.3 m3/day
TCE concentration in room during a shower	1033	ug/m3	Uniform 689 - 1378 ug/m3
Time per shower	10	minutes	Normal Mean: 10 minutes Std dev.: 5 minutes
Body Weight	52	kg	Normal Mean: 52 kg Std dev.: 10 kg
Exposure duration	10	years
Average lifetime	70	years
Cancer potency for inhalation	5.88E-6	kg-day/ug
Cancer potency for ingestion	4.6E-5	kg-day/ug

.Note that the EPA has withdrawn its cancer potency values from IRIS. I took the numbers in the table from other literature.