TRI Risk Assessment

Widows Creek multimedia health risk assessment

TVA, in cooperation with EPRI, has conducted a detailed, comprehensive, multimedia health risk assessment for its Widows Creek fossil plant in northeastern Alabama.

This particularly rigorous assessment, which considered potential exposure routes through air, water, food, milk, and skin contact, confirmed that TRI emissions from the plant do not pose a significant health risk to employees or nearby residents.

Inhalation risk assessments show health not at risk

In 2000 TVA conducted its third annual inhalation risk assessments for each TVA fossil plant. Our 2000 assessment results were similar to those of the previous two years, and to those of the U.S. Environmental Protection Agency (EPA) from 1998 and EPRI (the Electric Power Research Institute) from 1994, in concluding that TVA’s Toxics Release Inventory (TRI) air emissions pose no significant health risks to TVA employees or the public.

TVA compared maximum ground-level concentrations to:
- Acute (short-term) and chronic (long-term) occupational health guidelines developed by the American Conference of Governmental Industrial Hygienists
- Acute and chronic public noncancer health guidelines developed by the state of California.
TVA also used EPA’s cancer unit risk factors, which estimate increased lifetime cancer risk.
To ensure accuracy and credibility, TVA asked third-party specialists to review its results. These included risk assessment experts from the University of California at San Diego, EPRI, and the Harvard University Center for Risk Analysis.
TVA is confident that TRI air emissions from its plants do not constitute a significant health risk to employees or the public. These assessments will continue.
TVA’s risk assessment team determined that worst-case exposures estimated for TRI emissions from each of the plants were well below those in any of the risk assessment guidelines.

2000 inhalation risk assessment results

Occupational exposures: Maximum on-site TRI exposures were well below—often several hundred times below—all short- and long-term occupational exposure guidelines. TVA concluded that air TRI emissions do not represent an occupational health risk to TVA employees.

Public health exposures, noncancer: Maximum off-site TRI exposures were well below California acute and chronic hazard indicators.

Public health exposures, cancer: Maximum lifetime cancer probabilities for all TVA fossil plants were on the order of 3 in 1,000,000 or less. EPA’s acceptable range of excess lifetime cancer risk for the general population is 1 in 10,000 to 1 in 1,000,000. TVA concluded that air TRI emissions do not represent a cancer risk to the public.

Future study

As encouraging as the 1998, 1999, and 2000 TRI health risk assessments have been, the work to date is only a small part of TVA’s ongoing commitment to the health and safety of employees, Valley citizens, and the environment. It is important to remember that risk assessments are an ongoing process. Operating conditions often change significantly from year to year, as do the health guidelines and our understanding of the science of risk assessment.

In addition to ensuring that TVA employees and the public continue to be informed about TVA’s TRI emissions and fully in keeping with the spirit of Community Right-to-Know legislation, TVA will continue to use these risk assessment results to plan future environmental control strategies. In this way, we can benefit the greatest number of people at the lowest cost.