The Chemical World This Week
DATA ON OZONE, DRINKING WATER REFINED New studies are providing refinement to earlier findings in two areas of recent environmental concern: stratospheric ozone and drinking water. Results of the studies were presented last week in Mexico City at the First Chemical Congress of the North American Continent. Further studies of temperature effects on the ultraviolet light absorption cross section of chlorofluorocarbon 12 (dichlorodifluoromethane) carried out in the laboratory of chemistry professors F. Sherwood Rowland and Mario J. Molina at the University of California, Irvine, have added support to the hypothesis that stratospheric ozone is destroyed by chlorofluorocarbons. Solar photolysis of chlorofluorocarbons—used as aerosol propellants and refrigerants—is the lead reaction in a model proposed by Rowland and Molina in 1974. Chlorine atoms released by the photolysis initiate a catalytic chain reaction that destroys the ozone. Studies by others (C&EN, Sept. 1, page 15) found that because of low stratospheric temperatures, the absorption cross section of chlorofluorocarbon 12 at 2139 A is considerably lower than had been postulated on the basis of studies at room temperature. This finding has been corroborated by the work of the Irvine group, Dr. C. C. Chou of the group told the congress. However, the Irvine scientists point out
that the wave length is slightly outside the 1900- to 2100-A range important for chlorofluorocarbon 12 photolysis, and considerably larger temperature effects thus might be expected at that wave length. Indeed, the Irvine scientists find the ultimate temperature effects on the model to be much less significant. They measured the absorption cross sections for chlorofluorocarbon 12 over the entire wave length range and stratospheric temperature range and find that the weighted cross sections are only about 20% smaller than those measured at room temperature. Putting these cross sections back into their stratospheric diffusion calculations, they find that the resulting effect is to lengthen the atmospheric residence time of chlorofluorocarbon 12 about 10%. The net result, the scientists say, is that the changes determined in the new studies are not enough to make any qualitative change in the ozone depletion hypothesis. The chemists also measured the temperature effect for chlorofluorocarbon 11 (trichlorofluoromethane) with, they say, similar results. Meanwhile, data on dissolved organics in drinking water continue to build up. The significance of the findings in terms of toxicity is far from known—the compounds are present only in extremely trace amounts—but a more detailed picture of drinking water constituents is emerging. The latest findings come from a study of the drinking waters of 13 U.S. cities, carried out by the Athens, Ga., research laboratory of the Environmental Protection Agency. Following an earlier 1974 finding of 66 organic chemicals in New Orleans area drinking water supplies, EPA instituted a National Organics Reconnaissance Survey, analyzing for six halocarbons in the raw and finished waters of 84 cities. Of the 84, 10 were chosen for more comprehensive surveys, Dr. L. H. Keith of the Athens lab told the congress. These 10—Cincinnati, Miami, Ottumwa (Iowa), Philadelphia, Seattle, Grand Forks (N.D.), Lawrence (Mass.), New York City, Terrebonne Parish (Louisiana), and Tucson—were combined with the three New Orleans area supplies for thé Data on dissolved org a nics in drinking 13-city study. Working with carbon-column water continue to build up 6
C&EN Dec. 8, 1975
chloroform extracts from the 13 sites, the EPA lab has identified 109 different compounds and has partially identified eight more. In extracts from the 10 cities, 50 different compounds were identified. Concentrations of the dissolved organics in the 10-city extracts generally ranged from 0.01 to 5 ppb, although the highest single concentration was 30 ppb of di-(2-ethylhexyl) phthalate at Miami. Lowest was the less than 0.01 ppb of tetrachloroethylene found at Tucson. In its study, Keith says, the EPA lab has found another chemical that it believes is caused by drinking water chlorination: chloral, which exists in water as chloral hy-. drate (commonly known as knockout drops). Chloral was found in the water of Cincinnati, Philadelphia, Seattle, Grand Forks, New York City, and Terrebonne Parish in concentrations ranging from 0.01 ppb at Grand Forks to 5 ppb at Philadelphia. α
Borders no barrier at Mexico meeting A little pomp and ceremony, nearflawless organization, and calls for even greater international coopera tion in the chemical area marked the opening days of the First Chemical Congress of the North American Continent in Mexico City last week. The six-day gathering boasted an impressive scientific program of al most 1250 papers arranged in 12 di visions. By midweek registration was approaching 3500. More than six years in planning, the congress was sponsored by the American Chemical Society, the Chemical Institute of Canada, and the three major Mexican chemical organizations—the Mexican Chem ical Society, the Mexican Institute of Chemical Engineers, and the Pharmaceutical Association of Mexico. The congress was formally inau gurated by Mexico's secretary of in dustry and commerce José Campillo Sainz. He stood in for Mexican president Luis Echeverria Alvarez, the honorary president of the meeting, in a one-hour ceremony in Mexico City's ornate Palace of Fine Arts. The ceremony also included
presentation of a statement from Canada's prime minister Pierre Trudeau. Speaking on behalf of ACS at the ceremony, ACS president William J. Bailey expressed the hope that the meeting would lead to closer cooperation between Mexican and U.S. chemists in such areas as edu cation, publications, and techno logical exchange. He also stressed that ACS is interested in interna tional exchanges in general as chemistry itself is international in scope. He said it is in the self-inter est of ACS to see the development of a strong chemical community in Mexico. And he offered the cooper ation of ACS in such development. Elaborating on his remarks at a later conference with the Mexican press, Bailey said that the congress recognizes that chemistry in Mexi co has advanced to the point where U.S. chemists can have very mean ingful dialogue with their Mexican colleagues and learn a great deal from them. This growing strength of Mexican chemistry was well reflected in the congress program. 15% of all papers were by Mexican chemists. And in some divisions their participation was very high—for instance, 41% in the petroleum division, 35% in the industrial and engineering division, 27% in the biological, medicinal, and pharmaceutical division. α
Stauffer exec blasts EPA on pesticides The Environmental Protection Agency has mismanaged the ad ministration of the Federal Insecti cide, Fungicide, & Rodenticide Act, according to H. L. Straube, vice president and general manager of Stauffer's agricultural chemicals di vision. At a panel discussion held in Chicago, Straube, who also is chairman of the National Agricul tural Chemicals Association, charged that although FIFRA re quires EPA to consider both risks and benefits of pesticides, the agen cy has in fact adopted a "no-risk" attitude. He also took issue with an EPA Pesticide Enforcement Policy Statements (PEPS) that allows use of pesticides at lower-than-label dosages, if recommended by a rec ognized authority. "We stand be hind our labels," Straube declared. "Who is now responsible if a prod uct doesn't perform?" In addition, Straube argued that EPA's "selfgenerated" principles of carcinoge nicity "established a far-reaching principle without even asking the
Straube: we stand behind our labels
scientific community to comment or contribute." Dr. Jay Turim, an EPA pesticide programs official, defended the agency's aims and past actions. But he admitted steps were being taken "to improve decision-making," partly because of recent amend ments to FIFRA. There will be more open evaluation of risks and benefits, Turim said, and there will be more emphasis on nonadversary fact-finding hearings before moving to cancel or suspend a pesticide registration. As to carcinogenicity, the EPA-developed principles do "provide a firm basis in point of law," Turim contended. But he agreed that some of the principles are controversial and that they "leave basic questions unanswered. Even if there is a hazard, what should EPA do?" Two groups are now at work within EPA to formu late an overall cancer policy, which will include economic as well as health aspects, Turim revealed. John J. Neylan III of EPA's pes ticide enforcement division, main tained that the division will in crease the predictability of enforce ment actions. However, "they aren't fixed in granite." Neylan also answered Straube's question about deviations from labor recom mendations: "The user is responsi ble." D
PCB substitute is safe for environment Removing poly chlorinated biphenyls (PCB's) from the environment altogether may have moved a step closer last week as Dow Chemical and McGraw Edison announced development of a less environmen tally hazardous substitute for PCB's in high-voltage capacitors. The
compound will begin replacing PCB's in McGraw Edison's capaci tors in mid-1976. The new substitute material, butylated monochlorodiphenyl oxide, was developed by Dow and extensively tested by McGraw Edi son in a four-year joint program. It shows dielectric losses as low as or slightly lower than PCB mixtures while showing superior performance in corona discharge testing at most temperatures. In addition, it is ex pected to be safe from fire hazards at the normal operating tempera tures of capacitors, the company says. Environmentally, the new com pound performs substantially bet ter than PCB's, Dow says. Its major component is 45 times more biodegradable than PCB's, 30 times less bioconcentratable, and 20 times less toxic to fish in company testing. The material probably will cost 50 to 75% more than PCB mixtures, according to Dow, but since it will require less special handling and monitoring than PCB's do, the difference in cost for capacitors will be considerably less. PCB's have been used for the past 40 years in electrical equip ment because of their excellent di electric properties and low risk of explosion or fire. The evidence of their environmental hazard has led to strong opposition to their contin ued use (C&EN, Dec. 1, page 7). Since 1971 Monsanto, the only U.S. manufacturer of the compounds, has restricted their sales to closedsystem electrical applications where no acceptable substitute ma terial has been available. High-voltage capacitors of the type McGraw Edison makes proba bly are the second largest market for PCB's, after electrical trans formers. They represent about 20% of the estimated 40 million lb of these compounds consumed each year. The Dow-McGraw Edison mate rial joins several other PCB substi tutes already being tested or mar keted. Among them are Exxon Chemical's diisononylphthalate for capacitors, Dow-Corning's polymethyl siloxane fluid for transform ers, and an experimental fluid for transformers being developed by RTE Corp. Dow says it will have manufac turing capacity to produce 1 million lb per year of the new material by the first quarter of 1976. Should the fluid prove acceptable to the indus try, Dow is willing to make a com mitment to produce the fluid in multimillion lb-per-year quantities by the end of 1976. α Dec. 8, 1975 C&EN
7
