Though Stephen Johnson (search) has been the acting administrator at the Environmental Protection Agency since Mike Leavitt became secretary of Health and Human Services, his opportunity to get the job permanently could be stopped by two Democratic senators.

Sens. Bill Nelson (search) of Florida and Barbara Boxer (search) of California expressed their "shock and disappointment" Thursday in Johnson's failure to condemn an EPA program testing the effects of pesticides on children. They said that until he agrees to cancel the program, they're placing a hold on Johnson's nomination, preventing him from getting a vote on the Senate floor.

"If EPA can get away with testing babies, infants, then they can get away with anything when it comes to human testing of toxics," said Boxer, who added that when she questioned Johnson about the program and whether he would agree to cancel it, Johnson flatly refused.

"This is sick, it's a sick, sick thing," she said.

Boxer and Nelson said the EPA's Children's Environmental Exposure Research Study (search) offers to pay parents of a baby nearly $1,000 if they agree to expose their child to household pesticides over a two-year period. The study was being done in Duval County, Fla., in the Jacksonville area, a geographic location that appealed to the EPA because of its year-round use of indoor pesticides.

"I'm going to stand up for the health and safety of the children in my state. ... We need to be protecting children, not exposing them to pesticides," Nelson said.

The senators also suggested that the study was being conducted in a low-income, minority area where people would be more willing to participate in risky activities in exchange for money.

Holding up a can of Raid bug killer during a Thursday press conference, Boxer read the label, which warns that exposure of the product to children and pets could be harmful.

"'Avoid contact. Keep out of the reach of children. Remove pets, birds, cover your aquariums when you use this household spray.' This can of Raid is more ethical than the EPA, in my opinion," she said.

According to the EPA, CHEERS, which began in summer 2004, was suspended in November so the EPA could await an external, independent review by members of the Science Advisory Board (search), the Science Advisory Panel (search) and the Children's Health Protection Advisory Committee (search). The review is expected to be completed this spring.

An outline of the study available on the EPA's Web site says participants with children under 13 months of age are not required to begin using pesticides or to change any of their regular household routines. However, it asks that researchers be permitted to visit the home every three to six months over two years, at which time they will videotape the children's activities. Parents are also supposed to keep a diary of their children's behavior, collect food and urine samples, track pesticide use in the house and put a small watch-size sensor on the child to monitor his or her activities for one week every three to six months. About 30 families were signed up for the program when it was halted.

Johnson started at the EPA in 1979 as a health scientist in the Office of Pesticides and Toxic Substances. In a statement Thursday, the agency defended its approach, stressing that the study only involves families who already use pesticides.

The study "was designed to fill critical data gaps in our understanding of how children are exposed to pesticides and chemicals that are already found in typical household environments," the statement reads.

It added that the study "sought information to improve both risk assessment and risk management practices that would ultimately enable us to be more protective of children's health."

But Boxer compared testing on human subjects to Nazi experimentation and suggested that the Bush administration, in defiance of international standards, reversed a decision by former President Clinton to ban human testing (search). She added that she believes the pesticide industry was pressuring the EPA to pursue the tests.

"This program has numerous problems. To me, the most egregious: ethics 101. Testing pesticides on small children and infants is wrong. We already know it's bad for them," she said.

Boxer said that if Johnson does cancel the program — "if it is gone, never to rear its ugly, immoral head again" — then she would lift the hold on his nomination. She said that does not mean she would support his confirmation. A vote for Johnson in the Senate Environment and Public Works Committee is scheduled for next week.