The senators - four Democrats, one independent and one Republican - are concerned about the EPA´s plan to change the frequency of TRI reporting by businesses to once every two years from the current once per year.

"We are concerned that alternate-year reporting would deny citizens up-to-date information about local toxic releases, reduce incentives to minimize waste generation, withhold important information from public health agencies, and undermine the ability of states and EPA to guide their compliance assistance and enforcement priorities," the senators wrote to agency Administrator Stephen Johnson.

The EPA unveiled plans two months ago to adopt the change, saying alternate-year reporting would reduce burdens on businesses and the agency. The federal government would save money by cutting the number of annual TRI reports filed with the agency, and the taxpayer dollars could be redirected to improve the quality and accessibility of TRI information, according to the agency.

In their letter to Johnson dated Nov. 10, the six senators questioned the benefits of the change, saying widely available software makes the reporting tasks easier and less expensive.

Facilities that manufacture, process or otherwise use hazardous chemicals in quantities exceeding established thresholds must file TRI reports with the agency disclosing the amount and types of chemicals on their premises and the amounts released into the environment.

The senators also expressed concern about a proposal to allow thousands of facilities to withhold details about pollution volumes, and waste management and treatment if they release less than 5,000 pounds of toxic chemicals.

The letter to Johnson was signed by Sens. Barbara Boxer, D-Calif.; Hillary Clinton, D-N.Y.; Barack Obama, D-Ill.; Ron Wyden, D-Ore.; Jim Jeffords, I-Vt.; and John McCain, R-Ariz.