News of the Week
Herbicide 2,4,5-T could escape ban There is a flush of optimism these days among makers and users of the herbicide 2,4,5-T after more than a year of hearings in which the Environmental Protection Agency has sought to ban use of the compound and after two years of emergency suspension of many of its uses (C&EN, March 17, 1980, page 24). The most concrete evidence of a change in mood is a report last week from the American Council on Science & Health, which found the available scientific evidence insufficient to support a ban on the use of the herbicide. But there also are indications that EPA is backing off from its fight for complete suspension of the herbicide and is now willing to negotiate a settlement with manufacturers of the compound. 2,4,5-T, short for 2,4,5-trichlorophenoxyacetic acid, has been implicated in cancer, birth defects, miscarriages, and other serious illnesses. The most likely culprit for these effects is 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD), an extremely toxic trace contaminant that is formed unavoidably during production of 2,4,5-T. On March 24, lawyers for both Dow Chemical, the chief producer of 2,4,5-T in the U.S., and EPA asked for a recess in suspension hearings on the herbicide so that they could try to reach an out-of-court settlement of the issue. The recess has now been extended until May 12, with a progress report to be submitted on May 8. Neither EPA nor Dow will comment on the progress of these negotiations, but newspaper reports claim that talks so far have been concerned with the wording of more restrictive labeling that EPA wants to see on 2,4,5-T containers in exchange for allowing its continued use. Meanwhile, the American Council on Science & Health's report, based on a literature review, comes down almost entirely on the side of the producers and users of 2,4,5-T. "No scientific reports presented to date have shown any convincing relationship between the traditional use of 2,4,5-T and adverse health effects in humans," the council finds. "However, laboratory data strongly suggest that 2,4,5-T... should continue to be regulated." Every effort should be made to keep TCDD contamination of 2,4,5-T to a minimum, it says, and applications of 2,4,5-T, especially
from the air, should be monitored closely to keep unneccessary human and environmental exposure low. The council, a nonprofit consumer education association, is composed of scientists in health-related fields, primarily at academic institutions. Its past reports generally have found less cause for alarm than those of other consumer advocate groups from whom it sometimes draws criticism as being too "pro-industry." D
Technical job demand has rebounded sharply Although the U.S. general economy seems to have settled into the doldrums after an initial recovery in the second half of 1980, current job demand for technical professionals, including chemists and chemical engineers, is stronger than expected. And new technical graduates are still very much in demand with solid increases in salary offers. Contrary to fears last summer of an extended dip in job demand for technical professionals, the latest figures show a sharp rebound since last November, according to Deutsch, Shea & Evans in its monthly tallies for the winter. The New York City consulting firm says its high technology recruitment index hints at a rise to 140 (1961 = 100) in February by initial estimates after confirmed levels of 138 in January and 135 in December. The November low point was 128. These figures are threemonth running averages. DS&E won't say yet that the job market has definitely turned around. Statistically, that will take at least two more months of data. However, results from another group's survey on starting salary offers for new graduates also show a continued bright picture, especially for engineers. The College Placement Council, Bethlehem, Pa., finds salary levels well up from last July for nearly all the 24 curricula it surveys. Chemical engineers are doing particularly well. They have the second highest increase in starting salary offers for bachelor-degree graduates, 12.3% to $24,276. CPC does not disclose specific data for chemists but says starting salaries for B.S. graduates in the physical and earth sciences (excluding computer science) jumped 18% to $21,912. At the master's degree level, offers increased the most for chemical engineers—12.7% to $26,340. CPC does not disclose other data for M.S. or Ph.D. graduates. D
Bacteria may be used to degrade pollutants Upgraded microorganisms someday may help to degrade persistent pollutants, including residues of herbicides such as 2,4,5-T. Ananda M. Chakrabarty, a microbiologist at the University of Illinois Medical Center in Chicago, described progress toward developing such a bacterium during the Genetic Engineering 1981 International Conference held recently in Reston, Va., and sponsored by Battelle Memorial Institute. Chakrabarty's approach to developing suitable microorganisms hovers midway between a very traditional strategy for finding natural candidates and the more modern genetic engineering techniques. Thus, he and his colleagues don't do gene splicing in vitro; instead, they encourage microorganisms to do such tasks for themselves while growing in chemically controlled environments. For instance, microorganisms obtained from chemical waste dump sites are one source of candidates. They are grown in fermentors along with other microorganisms that were chosen because they carry plasmids (small molecules of DNA carrying only a few genes) enabling them to resist certain chlorine-containing antibiotics. The underlying strategy is to "supply pressure to the bacteria," Chakrabarty explains. "Instead of waiting for nature to do this, we must give a hand to the microorganisms . . . so they will evolve new ways to degrade pollutants." The bacteria are grown over long periods, and their source of nutrient carbon molecules is shifted gradually from an antibiotic, which some of the bacteria can degrade readily, to 2,4,5-T, off which no known bacteria can live. "We now can see degradation of more than 70% of the 2,4,5-T in a week," Chakrabarty says. This capability still is confined to laboratory strains of bacteria that probably are not hardy enough and certainly are not characterized enough yet to be thrown into the great outdoors to degrade herbicide residues. But Chakrabarty says he is heartened by these early successes and already is trying a similar strategy on other pollutant molecules. "The chemical industry should really be very agreeable to do research of this sort," he says. "Even if some don't care about societal obligations, there's money to be made. You can sell not only chemicals, but the antidotes to toxic chemicals." D
