Study: chlorination by-products, Onondaga Lake Improvement

An abstract of a paper that related to chlorination byproducts and bladder and rectal cancer was provided to the Lake Improvement Office. The paper, "Chlorination By-products Linked To Bladder, Rectal Cancers," December 1997, referenced two separate reports from the January issue of Epidemiology. Dr. Kenneth P. Cantor authored both reports.

These cancer studies focused on drinking water exposure to chlorinated surface water and ground water, and they are not unique. Many researchers are testing links between chlorination by-products found in drinking water and cancer.

Based on this research, USEPA has recognized some of these by-products as potential carcinogens. USEPA is reducing the risk from these by-products in drinking water by setting allowable maximum limits. As a frame of reference the following are maximum concentration limits for THM from different countries:

Country	Limit (µg/L)
United States	100
Canada	100
Germany	25
Switzerland	25

Exposure to these by-products from drinking water is very different than the exposure expected from a chlorinated combined sewer overflow (CSO). Ingestion rates and exposure frequencies are much lower from CSOs than from drinking water.

Whereas exposure to drinking water occurs every day (2 liters per day), exposure in the case of the proposed Midland facility's treated discharges of CSO will occur approximately ten times per year and ingested only incidentally upon swimming.

In addition, environmental dilution and by-product decay must be taken into account. When considering dilution and decay in the Onondaga Lake/Lake Ontario system, the concentration of THMs from chlorinated CSO would be negligible.

However, even without considering dilution and by-product decay, the absolute concentrations of by-products measured in chlorinated combined sewage are low compared to drinking water by-product concentrations. The table below shows total trihalomethane (THM) and haloacetic acid (HAA) concentrations measured in chlorinated combined sewage from Syracuse and New York City. The table also shows THM and HAA concentrations found in drinking water. In all cases the THM concentrations in the drinking water are higher than in the chlorinated/dechlorinated combined sewage.

Source	Total THM (µg/L)	Total HAA (µg/L)
WERF 2002 (Ref. 1)
Range	4-11	6-57
Average	7	24
NYC CS 2001 (Ref. 2)
Range	nd-58	42-80
Average	20	61
NYC DW 2002 (Ref. 3)
Range	13-75	16-64
Average	37	35
NYC DW 1998 (Ref. 4)
Range	8-80	18
Average	31	31
CND DW (96-99) (Ref. 5)
Range	1-348	Not reported
USGS DW (96-99) (Ref. 6)
Range	300-800	Not reported
See references below.

References

1. WERF 2002: "Identifying and Communicating the Benefits and Risks of Disinfecting Wet Weather Flows," Water Environment Research Foundation, Alexandria Virginia, ongoing.

2. NYC CS Yr 2001: Spring Creek AWPCP Upgrade Phase II CSO Disinfection Pilot Study, New York City Department of Environmental Protection, New York, NY, 2001.

3. NYC DW Yr 2002: New York City Annual Public Drinking Water Report, 2002, New York City Department of Environmental Protection, New York, NY, 2002.

4. NYC DW Yr 1998: New York City Annual Public Drinking Water Report, 1998, New York City Department of Environmental Protection, New York, NY, 1998.

5. CND DW (96-99): Trihalomethane Levels in Public Water Supplies of Newfoundland and Labrador. Chapter 4, "Data Analysis and Discussion," Department of Environment and Labour Newfoundland, 2001.

6. USGS DW (96-99): Potentially Deleterious Effects of Chlorinating Mississippi River Water for Drinking Purposes, U.S. Geological Survey Circular 1133, Reston, Virginia, 1995.