978-1118741498 Chapter 6 Part 3

6.27 Calculate a risk–based groundwater protection standard (in ppb) for the chemical

1,2-dichloroethane for a residential homeowner where the person’s well used for drinking

water is contaminated with 1,2-dichloroethane. Assume you are determining risk for an

average adult who weighs 70 kg. The state where you work has determined that an

acceptable risk is 1 cancer occurrence per 106 people. Use the values for route of intake,

exposure frequency, exposure duration, and averaging time provided for residential use in

Table 6.14. Assume an oral slope factor for 1,2-dichloroethane of 9.2 × 10-2 per

(mg/kg)/day.

Solution:

6.28 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 liters

of water per day with these chemicals dissolved at a concentration of 1 mg/L.

Solution:

6.29 A commercial area had its own separate groundwater supply system that provided

drinking water. Unfortunately the groundwater was contaminated with arsenic at a

concentration of 10 ppb. The property owner placed a deed restriction on accessing the

groundwater and also contacted the city to complete a hookup with the city water supply.

Determine if exposure by oral ingestion to the chemical arsenic poses a noncarcinogenic

health risk for individuals consuming drinking water after the property owner’ actions

have taken place. Assume a 70 kg individual consumes 2 liters of water per day and the

reference dose for arsenic is 0.0003 mg/kg-day.

Solution:

6.30 (a) Calculate a risk-based groundwater protection standard for the chemical

benzo(a)pyrene. Assume you are determining risk for an average adult female who

weighs 50 kg and consumes 2 L water and eats 30 g fish per day. The state has

determined that an acceptable risk is 1 cancer occurrence per 105 people. Use the values

for exposure frequency, exposure duration, and averaging time provided for residential

land use. (b) According to EPA’s Integrated Risk Information System (IRIS), what type

of carcinogen is benzo(a)pyrene, using the weight of evidence of human and animal

studies? (c) Assuming the chemical is leaching from some contaminated soil, estimate the

allowable concentration of benzo(a)pyrene in the pore water of contaminated soil.

Solution:

6.31 Is there an unsafe risk associated with a 70 kg adult eating 15 g fish every day that

contains 1 mg/kg of methylmercury? Methylmercury has been shown to cause

developmental neuropsychological impairment in human beings. The RfD for

methylmercury is 1 × 10-4 mg/kg–day.

Solution:

6.32 Is there an unsafe risk associated with a 70 kg adult eating 15 g fish every day that

contains 9.8 µg/ 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.

Solution:

6.33 Concentrations of toxaphene in fish may impair human health and fish-eating birds

(such as bald eagles) that feed on the fish. (a) If the log of the octanol–water partition

coefficient (log Kow) for toxaphene is assumed to equal 4.21, what is the expected

concentration of toxaphene in fish? (Assume that the equilibrium aqueous phase

toxaphene concentration is 100 ng/L.) (b) If it is assumed that an average person drinks 2

L untreated water daily and consumes 30 g contaminated fish, what route of exposure

(drinking water or eating fish) results in the greatest risk from toxaphene in 1 year? (c)

What route of exposure is greatest for a higher-risk group that is assumed to consume 100

g fish per day? Support all of your answers with calculations. Assume the following

correlation applies to toxaphene and our problem’s specific fish:

ow

log BCF 0.85log 0.07K= −

Solution:

6.34 Identify a brownfield in your local community, hometown, or a nearby city. What

was specifically done at the site? What are several social, economic, and environmental

issues associated with restoring the brownfield site?

Solution:

Students’ responses will vary.

6.35 The Code of Federal Regulations (CFR) is the codification of the general and

permanent rules published in the Federal Register by the executive departments and

agencies of the Federal Government. It can be accessed at http://www.gpoaccess.gov/cfr/.

What CFR number is associated with the following sections? (for example, 50 CFR for

Wildlife and Fisheries). (a) Protection of Environment; (b) Transportation, (c)

Conservation of Power and Water Resources, (d) Public Health, and (e) Highways.

Solution:

6.36 Research the safety of your personal care and household cleaning products using a

web site such as http://lesstoxicguide.ca/index.asp?fetch=personal. Develop a table that

lists 7 current personal care or household cleaning products used in your apartment,

home, or dormitory. Add a second column that lists a less hazardous alternative for each

of the 7 products.

Solution:

Students’ responses will vary but an example table is listed below.

Product

Non-hazardous alternative

1. Crest toothpaste

1. Arm and Hammer Teeth Whitening Booster

Toothpaste

2. Garnier Fructis hair conditioner

2. Dr. Bronner’s Magic Organic Citrus Hair Rinse

3. OB non-applicator tampons

3. Diva cup

4. Garnier fructis hair gel

4. Aloe vera gel

5. Oil of Olay Face Cream

5. Shea butter

6. ACT fluoride rinse

6. Tom’s of Main Natural Baking Soda

Mouthwash

7. Tom’s of Main Natural

Deodorant

7. Make your own recipe with cornstarch

6.37 Do some background research. Some good places to look for this and related

information include EXTOXNET, the National Toxicology Program (NTP), the Agency

for Toxic Substances and Disease Registry (ATSDR), and the National Library of

Medicine (choose one). (a) Is atrazine bioaccumulative and/or persistent in the

environment? Explain your answer. (b) Now consider applying atrazine to your lawn

and assume that there are children in the household and they like to eat grass, dirt, and

worms while playing on grass. Assume the atrazine is both bioaccumulative and

persistent. How does this new information about the partitioning and persistence

behavior of atrazine affect your consideration of the potential toxicity of atrazine to

humans?

Solution: