Artificial Turf

The study, was undertaken more than two years ago amid increasing concerns that the fields - made of old tires ground into small pellets and plastic blades that mimic real grass - could pose a public health risk. Critics were worried that the fields harbor dangerous bacteria that would lead to more skin infections and could release toxic chemicals into the air, particularly when temperatures rise.

The state's study concluded that there are actually fewer bacteria on artificial turf fields compared with natural grass.

State researchers did find some "volatile organic compounds" - such as lead and other heavy metals - in the air near the fields, but the presence of these toxins was so low that no public health concern was identified. And, because there was no relation between the surface temperature and the concentrations of those chemicals, the study's author said there is no reason to recommend that field usage be limited when it's hot.

The study - conducted by state environmental officials for the California Department of Resources Recycling and Recovery- did find, however, that college soccer players suffer far more skin abrasions when they play on artificial turf than with natural grass. It recommends working to prevent those abrasions, in part through protective clothing and equipment.

Scientists "measured the chemicals and particulates in the air, the bacteria in the turf and looked at skin abrasions caused by contact with the surface," said Sam Delson, a spokesman for the state Office of Environmental Health Hazard Assessment. "Essentially we didn't identify any health concerns, other than that there is a higher rate of skin abrasions."

Critics remain, however. Steve Ambrose, one of the Potrero Hill residents who helped beat back plans to install synthetic turf at a local park in that neighborhood several years ago, noted the higher rate of skin abrasions cited in the study.

"The rate is two- to three-fold higher (than on natural grass) - that's an enormous difference," he said. "Do you want your kid playing on a surface that triples the rate of injuries?"