National Academies Press: OpenBook

Risk Assessment of Radon in Drinking Water (1999)

Chapter: D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)

« Previous: C Water-Mitigation Techniques
Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×

D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)

1) Ingestion of Household Water with THMs General Assumptions

Drinking-water intake: 0.6 L d-1

Body weight: 70 kg

Person drinks water at home 7 d wk-1, 52 wk y-1

Exposure duration: 70 y

Averaging time for carcinogenic effects: 70 y (25,550 d)

Unit Dose Factor for Cancer Risk (lifetime average):

2) Inhalation Intake from Household Water with THMs Assumptions

Inhalation rate of moderately active people: 0.77 m3 h-1

Duration of time in house during a day: 17 h

Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×

Exposure duration: 70 y

Averaging time for carcinogenic effects: 70 y (25,550 d)

Average transfer coefficient = 0.1 µg / m3 (air)/µg/L (water)

Unit Dose Factor for Cancer Risk (lifetime average):

3) Dermal Uptake from Bathing at Home Assumptions

Body weight: 70 kg

Area of body exposed during bathing: about 20,000 cm2 (in the range of central to upper estimate from EPA guidance)

Effective permeability of THMs through skin for a 10-min exposure: 0.05 cm h-1, based on value for chloroform estimated by McKone (1993) from EPA and other models

Bath or shower for 0.17 h (10 min) once per day, 365/day

Exposure duration: 70 y

Averaging time for carcinogenic effects: 70 y (25,550 d)

Unit Dose Factor for Cancer Risk (lifetime average) =

In the tables below, Risk = Cw x UDF x Potency.

The total risk for each chemical is the sum of the risks across the three exposure routes.

Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×

Summary Table of Risk Estimates for THMs in Surface Water

 

 

Compound

 

 

Chloroform

Bromodichloromethane

Chlorodibromomethane

Bromoform

Total Risk

Water Concentrationa µg L-1

 

90

12

5

2.1

 

 

Unit Dose Factor

Potencies by Route

 

 

 

Ingestion

0.0086

0.031

0.13

0.094

0.008

 

Inhalation

0.019

0.019

0.13

0.094

0.004

 

Dermal uptake

0.0024

0.019

0.13

0.094

0.004

 

Total risk by chemical

 

6.1 × 10-5

4.7 × 10-5

1.4 × 10-5

3.2 × 10-7

1.2 × 10-4

a Data from Brass and others (1981).

Summary Table of Risk Estimates for THMs in Ground Water

 

 

Compound

 

 

Chloroform

Bromodichloromethane

Chlorodibromomethane

Bromoform

Total Risk

Water Concentrationa µg L-1

 

8.9

5.8

6.6

11

 

 

Unit Dose Factor

Potencies by Route

 

 

 

Ingestion

0.0086

0.031

0.13

0.094

0.008

 

Inhalation

0.019

0.019

0.13

0.094

0.004

 

Dermal uptake

0.0024

0.019

0.13

0.094

0.004

 

Total risk by chemical

 

6.0 × 10-6

2.3 × 10-5

1.9 × 10-5

1.7 × 10-6

4.9 × 10-5

a Data from Brass and others (1981).

Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×
Page 254
Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×
Page 255
Suggested Citation:"D Risks Associated with Disinfection By-products Formed by Water Chlorination Related to Trihalomethanes (THMs)." National Research Council. 1999. Risk Assessment of Radon in Drinking Water. Washington, DC: The National Academies Press. doi: 10.17226/6287.
×
Page 256
Next: E Gamma Radiation Dose from Granular-Activated Carbon (GAC) Water Treatment Units »
Risk Assessment of Radon in Drinking Water Get This Book
×
Buy Hardback | $68.00 Buy Ebook | $54.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

The Safe Drinking Water Act directs the U.S. Environmental Protection Agency (EPA) to regulate the quality of drinking water, including its concentration of radon, an acknowledged carcinogen.

This book presents a valuable synthesis of information about the total inhalation and ingestion risks posed by radon in public drinking water, including comprehensive reviews of data on the transfer of radon from water to indoor air and on outdoor levels of radon in the United States. It also presents a new analysis of a biokinetic model developed to determine the risks posed by ingestion of radon and reviews inhalation risks and the carcinogenesis process. The volume includes scenarios for quantifying the reduction in health risk that might be achieved by a program to reduce public exposure to radon.

Risk Assessment of Radon in Drinking Water, reflecting research and analysis mandated by 1996 amendments to the Safe Drinking Water Act, provides comment on a variety of methods to reduce radon entry into homes and to reduce the concentrations of radon in indoor air and in water. The models, analysis, and reviews of literature contained in this book are intended to provide information that EPA will need to set a new maximum contaminant level, as it is required to do in 2000.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!