Tina Bahadori says a career at the U.S. Environmental Protection Agency has given her the chance to achieve something that 25 years in the private sector didn't offer: a legacy.

Bahadori's years working for consulting, advocacy and lobbying firms brought her success and money. But as national program director for the EPA's chemical safety and sustainability research, she says, she's effecting change.

"There is nothing more rewarding and legacy-building as a scientist who works in the environmental and public health arena," said Bahadori, a chemical and combustion engineer with degrees from the Massachusetts Institute of Technology and Harvard University.

The Washington woman is one of thousands of scientists and researchers hired by federal agencies in recent years under special authority to help the government compete with the private sector for high-level professionals to fill senior leadership positions.

The agencies can offer higher pay in certain specialized fields and provide recruitment and retention bonuses. But government watchdogs have warned officials to use the authority judiciously.

"It is important for agencies to have pay flexibilities and other tools and incentives available so that they are able to complete in the labor market for top-notch talent," said Robert Goldenkoff, director of strategic issues at the Government Accountability Office.

"At the same time, agencies and [the Office of Personnel Management] need to ensure the flexibilities are used only when necessary to support agency mission and program needs and that their usage is consistent with applicable laws, guidance and internal controls."

Bahadori believes her work on chemical safety, along with that of others, will touch most American households by helping families make informed decisions about which products could be harmful to them based on their particular health issues and lifestyle.

"It serves the greater good," she said.

The standard government pay scale maxes out at $130,810. Workers in expensive locations can earn more based on cost-of-living adjustments in major metropolitan areas.

Under special hiring authority known as Title 42, the EPA and the Department of Health and Human Services, the parent agency for the Bethesda-based National Institutes of Health, can pay certain employees a salary of up to $250,000 and bonuses of up to another $25,000.

HHS has used the special authority for an increasing number of workers, from 5,360 in 2006 to 6,700 in 2010. During the same period, the EPA had hired 17 under that authority. Federal officials did not respond to request for more recent data.

The GAO advised the agencies in a July 2012 report to use "robust policies and internal control mechanisms" when hiring employees under Title 42.

Bahadori, who joined the EPA in May 2012, called the Title 42 hiring authority pivotal. Researchers the agency brought in under the program were recruited for their talents and ability to influence science and policy in specific realms, she said.

"It's like a chess board," Bahadori said. The EPA uses Title 42 to "fill the pipeline from science to policy."

The extra hiring authority helps the agencies find workers in areas where they have traditionally had trouble recruiting, said Jacqueline Simon, policy director for the American Federation of Government Employees. The union represents 650,000 government workers nationwide and overseas.

The salary perks help compensate for pay gaps in the standard salary scale, Simon said. The federal government has fallen short of the requirements laid out in a 1990 law that directs officials to close a pay gap between federal workers and their counterparts who perform the same jobs in the private sector, she said.

"To say the federal pay system hasn't been working is an understatement of tremendous magnitude," Simon said. She said federal recruitment is hurt when salaries are frozen and Congress uses federal workers as "political punching bags."

Simon said federal workers serve significant national interest in areas of climate research, biomedical developments, aerospace advances and cybersecurity.

"There are public benefits for all of this," she said.