The U.S. Court of Appeals has told the Labor Department that it cannot allow 10-and 11-year-old children to work in pesticide-treated fields until the department is assured that those children will be safe from any harmful exposure to pesticides and chemicals used on crops.

In related development, the Labor Department and the Environmental Protection Agency announced last week that they have agreed to a $5 million joint protect over the next five years to determine the effects of pesticide exposure on children under 16.

The appeals court opinion, written by Senior Judge David L. Bazelon, seemed to indicate that 10- and 11-year-old children will be kept out of the fields at least until that five-year study is completed.

Both the court decision and the project center on a 1977 amendment to the Fair Labor Standards Act, which says growers can obtain permission from the Secretary of Labor to employ 10- and 11-year-olds if the growers can prove, by "objective data," that the types and levels of pesticides and chemicals used would not have an adverse affect on those children.

When Congress approved tha limited exception to the child labor laws, it intended to impose strict conditions that would ensure the safety of young children who work the fields by hand, Judge Bazelon wrote. The legislative history shows that Congress would accept nothing less from the agency than "absolute safety standards," Bazelon said.

In the court of appeals, two organizations that represent farmworker families challenged the government's first attempt to come up with protective standards for children who harvest fields sprayed with pesticides. The farmworker groups were represented by Ralph Nader's Public Citizens Litigation group.

In 1978, the Labor Department first tried to come up with a set of standards that growers could use to determine if they could assure the safety of children who work with pesticide-treated crops. The department soon learned from various sources, most signigicantly from the U.S. Environmental Protection Agency, that no one had enough knowledge of the effect of pesticides on children to support any safety standards.

As a result, the Labor Department told growers that if they wanted to get a waiver -- so they could hire 10- and 11-year-old children -- they would have to state either that they did not use pesticides at all or come up with proof that those children would not be harmed if they were exposed to the pesticides used.

The department, however, under pressure from farm groups that had gone to federal court in Washington stae, later took another look at those regulations.

A decision by that court allowed more than 3,900 under age 11 to work during the June 1979 strawberry harvest, because, the court said, the department had not acted quickly enough on the growers' request for waivers.

At that point, the Labor Department, pressed to expedite the waiver process, decided it would specify safety standards to be met by growers who wanted waivers. "If we didn't do something the courts would have allowed the children to work in the fields with no controls at all," a Labor Department official said later.

The department hired a private consultant, Clement Associates, to develop criteria, that the department could use when it considered waiver requests. The result was that more than 30 pesticides were placed on a list of approved pesticides that could be used before children came on the fields -- provided there was a required lag time between the spray and the start of the children's work.

EPA challenged the list, Bazelon wrote in his opinion. Noting that children are particularly susceptible to the toxic effects of pesticides, EPA again said it did not have sufficient information to make any recommendation on safe conditions for children in fields where pesticides had been used. Some of the pesticides included on the Labor Department's approved list were identified by EPA as "high-risk pesticides" and others were described by EPA as "highly toxic," Bazelon said.

Moreover, Bazelon said, the government's consultant admitted it had no information to assure the safety of the children.

Bazelon said the department has approved the standards for children with "no data" that would even tend to show that the children would not be adversely affected by the pesticides and chemicals that had been used on the fields. The consultant's report not only expressly disclaimed any assurances of safety, Bazelon said, it also recommended that the children exposed to the pesticides be placed under medical supervision.

Bazelon said that the government had failed to come up with the required objective data to show that the types of pesticides and chemicals used would not adversely affect the children. In addition, Bazelon said, the department failed to solicit comment from the public on the proposed regulations, particularly from the families of the children who would be working in those fields.

The appeals court had blocked use of the regulations immediately after oral argument on the case Feb. 15. Last Thursday, Bazelon, joined in his opinion by Chief Judge J. Skelly Wright and Judge Malcolm R. Wilkey, explained the court's reasons for its decision. Wilkey also reserved his right to file a separate opinion in the case at a later date.