This excerpt is from the Trichloroethylene Health Effects Fact Sheet (Jan. 2005) from Colorado Department of Public Health and Environment:

New Interim Policy for TCE Screening and Cleanup
Federal regulatory standards, called Maximum Contaminant Levels, have been established for TCE in water. Because there is no established national standard for TCE in air, the Colorado Department of Public Health and Environment in August 2004 established a new interim policy revising screening and clean-up levels for TCE. The state of Colorado uses a calculated risk-based level to determine when action may be taken to prevent residential exposure to TCE. The most protective end of the cancer factor range is based upon a residential exposure scenario in which a person theoretically is exposed to TCE for 24 hours-a-day, 350 days a year for 30 years (including 6 years of exposure as a child and 24 years as an adult).

The Colorado Department of Public Health and Environment’s interim policy is intended to provide guidance for risk management decisions at Colorado sites subject to the Department’s regulatory authority. Under the new interim policy, risk screening will use the most protective level of 0.016 micrograms/parts per billion per cubic meter of air and may involve indoor air testing. This screening level is based on a risk level of one additional cancer in 1,000,000 people. If TCE levels in a home range from 0.8 to 1.6 micrograms/parts per billion per cubic meter of air, the Colorado Department of Public Health and Environment intends to conduct further study to determine the source(s) of contamination and whether remediation will be required. Sources could include groundwater or emissions from household products. Due to the uncertainty associated with ongoing evaluation of TCE health risk assessment, the Colorado Department of Public Health and Environment will continue to use the standard of one additional cancer in 10,000 people as the maximum acceptable risk.

Remediation of TCE
If TCE levels meet or exceed 1.6 micrograms per cubic meter of air, and the levels are attributable to an environmental source, the party responsible for the contamination may be required to provide a ventilation system for the home. This involves the use of relatively simple fan and vent systems that draw air from beneath the building and prevent vapors from ever entering the structure. This is the same method used to effectively remove radon from buildings.

Read the fact sheet in HTML or download the PDF (53 KB)