School District of Lancaster, Manheim Twp. Sch. Dist.,lampeter-strasburg Sch. Dist., Northeastern Sch. Dist. v. Lake Asbestos of Quebec, Ltd., Celotex Corp., Raymark Ind.,inc., Union Carbide Corp., Asbestospray Corp., Sprayo-flakeco., Nat. Gypsum Co., Sprayed Insulation, Inc., Asbestosfibres Inc., Dana Corp., U.S. Gypsum, U.S. Mineral Prod.co., Sprayon Insulation & Acoustics, Inc., Sprayon Reasearchcorp., Keene Corp., Worben Co., Inc., Wilkin Insulation Co., W.r, 950 F.2d 723 (3d Cir. 1991)