Today City Council is hearing arguments for a bill that would prohibit the use of artificial rubber in all city playgrounds and fields. The bill comes on the heels of the temporary shutdown of Thomas Jefferson Park, a soccer field at 113th Street and First Avenue where five times more lead than the Environmental Protection Agency allows in playground soil was discovered in December. Advocates of the bill say that dangerous amount of toxins are contained in the "tire crumbs" that make up the turf. Co-sponsor of the legislation Councilman Eric Giola said yesterday, "You wouldn't let your children play in a junkyard, but many of the same chemicals are in this material." The Parks Department says that Thomas Jefferson Park is an aberration, possibly caused by coal that was there in years past. Parks Commissioner Adrian Benepe adds that grass parks may not actually be more environmentally conscious when you factor in the pesticides, herbicides, aeration and millions of gallons of water that go into maintaining them.