HARRISBURG, Pa. - A court is expected to rule on whether a central Pennsylvania township has the right to prohibit the use of human sewage as fertilizer on agricultural land, a practice that some critics believe could be harmful to people.

But the Commonwealth Court decision likely will not answer questions about whether the processed sewage is safe or if it is properly screened and tested before being spread on fields where crops are grown and animals graze not far from homes.

The state Attorney General's Office challenged the East Brunswick Township ordinance after receiving a complaint from J.C. Hill Tree Farms. Enacted in December 2006, the ordinance bans corporations from spreading sludge that results after wastewater is treated by municipal systems.

Residents wanted the ordinance out of concern for their health.

In addition to East Brunswick, about 65 miles northwest of Philadelphia, towns and counties in several other states have fought to keep out the sludge, which the industry calls biosolids.

But in its Oct. 3 court filing, the Attorney General's Office said the ordinance violates state waste-management and nutrient-management laws, which do not allow municipalities to regulate sludge.

An attorney for the township, Thomas Linzey, argues that the township ordinance regulates corporations, not sludge, and cannot be preempted.

Tree-farm owner J.C. Hill said he stopped spreading biosolids on his land after East Brunswick approved the ordinance, but he maintains that years of academic study have found that it is a good source of nutrients for plants.

Opponents, however, say it's a health hazard.

Linzey said the state's requirement that the sludge, as it is called by opponents, only needs to be periodically tested leaves a wide open hole for polluted truckloads to escape notice.

"You're in a situation where this can be a very dangerous and toxic stream of sludge coming in, and the state regulations do not protect people," Linzey said.

The Commonwealth Court said Wednesday that it would issue a decision in the case.

Federal and state laws allow the use of sludge as fertilizer for farms, lawns, gardens, parks, golf courses and former industrial lands. There are standards for how the sludge must be treated, and restrictions on how it's applied.

Often, farmers get it for free since it's cheaper to truck it to them than to dump it in a landfill. The amount being used as fertilizer is climbing, although it is applied to less than 1 percent of the nation's 931 million acres of agricultural land.

Human waste is the primary organic ingredient in the biosolids.

But critics worry about the pathogens, toxic metals and thousands of industrial, household and commercial chemicals that end up in sewers - many of which are not screened out of sludge.

Charles N. Haas, a professor of environmental engineering at Drexel University, said he has seen no scientific literature to prove allegations that biosolids have caused illness or death.

However, a National Academy of Sciences panel, on which Haas served, said in 2002 that there has not been enough analysis to determine whether exposure to sludge can be harmful to humans.

Researchers are looking at how such studies should be designed, Haas said.

In addition, the inspector general of the U.S. Environmental Protection Agency and the National Academy of Sciences have faulted the adequacy of the science behind the EPA's 1993 biosolids regulations.

In Pennsylvania, about 10 pollutants are screened.

"That's a pretty short list. We know there are hundreds of types of organic chemicals, and it's probably fair to say thousands, in sludges, probably some that are toxic and some that are not," said Murray B. McBride, a soil chemist and director of the Waste Management Institute at Cornell University in Ithaca, N.Y. "But by no means has there been careful study on any significant percentage of those chemicals."