Document G6Laybp5xdLyD9XNX5rb0emqN

V$\VD-rU \No\U6A0 \ >_\ "'-T'/ ";..... (jl '(/) = Gv^. 'fj tiii'i' j fOvy ^1 GliSiM EM TEllS OSSU :(j< ) V,' 0" SPECIALTIES: Versatile polymer Upjohn Co.'s fine chemical division has introduced Photozid, a polymer combining UV-sensitive photobond ing groups and dye receptor sites. The polymer bonds to varied ma terials such as plastics, metals, ce ramics, paper, and glass. Upjohn says it should find many uses in the graphic arts, in the electronics in dustry, and as a "photo-glue" to bond difficult-to-join materials. Photozid is the reaction product of a maleic anhydride copolymer and a hydroxy-terminated arenesulfonyl azide. Typically, it is applied in a very thin (0.5 to 2.0 microns) film to a substrate, using conven tozid offers higher resolution than silver halide systems. It needs no darkroom, he adds, and it can be used in aqueous media. Potential applications in the graphic arts include decorating china, labeling glass and plastic con tainers, making transparencies, and improving the ink receptivity of low-polarity polymers. Commercial development mana ger C. W. Stewart points out that the polymer can also be used as a negative photoresist for etching cop per printing plates or electronic cir cuit boards, and to bond magnetic particles to polyester tape. At present, the cost of Photozid figures out to about 2 cents per square foot of coating; this rela tively high price will probably limit Photozid's use, initially, to those applications where it can provide some unique qualitative advantage. Mr. Stewart predicts, however, that economies of scale will eventually bring about lower prices, PUBLIC HEALTH: ^/'XXj No threat from PCb's tional coating techniques. Irradia tion for a fraction of a second with ultraviolet light decomposes thesulfonyl azide to yield, among other things, a highly reactive nitrene that not only cross-links with adjacent polymer chains but bonds with the substrate. Carboxyl groups serve as receptor sites for basic dyes. Dr. Henri Ulrich, manager of chemical research at Upjohn's Don ald S. Gilmore Laboratories (North Haven, Conn.) and one of the dis coverers of the polymer, explains that durable images are easily pro duced. A mask or negative is placed over the Photozid-coated sur face before it is exposed to UV light. After exposure, the unreacted (un exposed) polymer is washed off and a basic dye is applied to react with the remaining Photozid. Multicolor images can be made with sequen tial exposures through different masks. Dr. Ulrich boasts that Pho The Government, basing its judg ment on current knowledge, sees no imminent threat to the safety of the food supply or to the public health from polychlorinated bi phenyls (PCB). Dr. Charles C. Edwards, spokesman for FDA, be lieves that the confusion over the danger from PCB's is being com pounded by alarmists and "unbal anced reporting." According to Dr. Edwards, the Government and industry have been actively eliminating potential and actual PCB contamination of the food supply since 1966. In spite of these efforts there have been some isolated instances of food contamination. On behalf of FDA, Dr. Edwards rejects the idea that crisis head lines and demands for national health alerts are either justified or needed to meet the present situa tion. He observes that science does not support such actions and that FDA will continue to abide by the dictates of science in mak ing regulatory judgments on behalf of the consumer. In summarizing its actions on the PCB problem, FDA applauds the co operation of industry. Specifically, Monsanto, the primary domestic producer of PCB's, is now selling PCB's only for nonfood uses. Na tional Cash Register Co. has also " Wv. I U _________________ ;____________ j ACS Group Insurance Payments deferments for unemployed members of the ACS Group Life In surance Plan and an increase in bene fits are described on page 53. stopped using PCB's for its car bonless carbon paper. The paper has been withdrawn from the pro duction of recycled packaging ma terials. Except for isolated incidents in volving fish, FDA says that almost all of the high levels of PCB's found to date have been associated with accidents which FDA is working to prevent. FDA has also stepped up its surveillance of the food supply to detect PCB's and has entered into a coordinated government ef fort under the direction of the Of fice of Science and Technology and the Council on Environmental Qual ity to deal with the problem. Dr. Albert C. Kolbye, deputy di rector of FDA's Bureau of Foods, classifies PCB's as moderately toxic, and certainly much less toxic than DDT. He observes that animal and human data point to 150 to 300 micrograms per day as being in the safe range as far as temporary dietary intake is con cerned. According to Dr. Kolbye, FDA is not aware of any foods con taminated on a regular or consist ent basis. URANIUM TAILINGS: No one's responsibility In a controversy over the use of sandlike uranium mill tailings for construction purposes the Atomic Energy Commission and the state of Colorado over the past two weeks have been issuing disclaimers with ever-increasing frequency. The is sue appears to be boiling down to a classic case of no one's wanting responsibility for the wastes left after extraction of a natural resource. The buck may well be passed on to owners of homes in which the radioactive, perhaps can cer-causing, material was used, A federal-state interagency com mittee on the radiation problem as sociated with tailings recommended that all tailings be removed from within 10 feet of habitable struc tures. On the committee, the state health department and representa tives of the federal Environmental Protection Agency voted in favor of the recommendation. AEC and U.S. 12 C&EN OCT. 4, 1971 ll DSW 378644 STLCOPCB4099897