The Prince George's County Council approved legislation yesterday requiring anyone who uses pesticides on lawns, golf courses or rights-of-way to post warning notices when the chemicals are sprayed.

The 7-to-2 vote in favor of the pesticide measure capped a five-month lobbying effort by environmental and animal rights activists and immediately followed a public hearing at which the activists told grim stories of the dire effects of chemical poisoning.

In other action, the council approved a bill that would regulate workers in day care centers and authorized the sale of bonds to permit a private developer to purchase the troubled Chillum Heights apartment complex.

Only council Chairman William B. Amonett and member Richard J. Castaldi opposed the pesticide measure, which they argued is unenforceable and runs counter to an advisory opinion on the matter issued yesterday by Maryland Attorney General Stephen H. Sachs. Sachs said that the mandatory provisons of the Prince George's measure and a similar one pending before the Montgomery County Council are preempted by federal environmental law.

More than 30 persons testified on the Prince George's bill yesterday, most of them supporting it. County health officer Helen B. McAllister said her office continues to receive calls from residents complaining of "noxious odors" caused by nearby pesticide applications.

"Many of the pesticides used on lawns today have not been fully tested," said David Reznikoff, who represented the Gray Panthers. "We are drowning in toxics and we don't even feel it."

But Mike Tidd, owner of Lawn Doctor of Northern Prince George's County, said greater unregulated health risks can be found in ordinary household products. "The perceived danger is much greater than the actual danger," he said.

Voting for the measure were council members Anthony Cicoria, Sue V. Mills, James M. Herl, Hilda Pemberton, Jo Ann T. Bell, Floyd E. Wilson and Frank Casula.

The legislation providing for licensing child care workers in the county would affect an estimated 4,000 workers and require them to undergo criminal background checks before they are allowed to hold jobs in day care centers.

The 7-to-0 vote, with Castaldi abstaining and Pemberton absent, sends the bill to County Executive Parris Glendening for his signature. The executive's liaison officer, Howard Stone, said it will be signed into law, although Glendening vetoed a similar bill last year, saying that the cost of administering such a licensing procedure would be prohibitive. The law would go into effect July 1.

Before approving the bill, the council amended it to reduce a proposed $25 licensing fee to $10, a move designed to defuse objections raised by representatives of the county's child care industry.

"We are dealing with the children of Prince George's County," said Herl, the bill's sponsor. "And it amazes me we have such a hard time passing legislation aimed at criminal background checks on people who handle children."

The council approved a resolution that authorizes the county to float up to $42 million in housing bonds for the Bethesda-based Artery Organization Inc. to purchase and renovate the Chillum Heights Apartments in the northern part of the county.

The 76-building, 952-unit complex had been under a county order to stop renting apartments since April, when officials cited more than 200 code violations.

Riddick said Artery, as part of its agreement to receive the low-interest bond financing, has agreed to provide relocation payments of $600 to $800 each for tenants who are forced to move because of the renovations. Rents, which now range from $313 to $346 a month, will jump about 12 percent, Riddick said, and tenants will begin to pay electricity costs.

Wanda Ricks, vice chairwoman of the tenant organization at Chillum Heights, said the county and the new developer have not made enough provisions for the lowest-income tenants, who cannot afford to move.

"I really think there won't be anybody left, to be frank with you," she said.