Chloroform precursors found in natural waters - C&EN Global

Eng. News , 1977, 55 (23), pp 6–7 ... Eng. News Archives ... Great Lakes basin, chemists Barry G. Oliver and John Lawrence at Canada Centre for Inla...
1 downloads 0 Views 344KB Size
The Chemical World This Week

SCIENTIFIC COOPERATION URGED AT MONTREAL What last week's 2nd Joint Confer­ ence of the Chemical Institute of Canada and the American Chemical Society held in Montreal lacked in volume of attendance (nearly 3000), it made up in good-natured "hands across the border" style. Officials of both organizations set the tone for this in the remarks opening the meeting. Dr. Anna J. Harrison, ACS presi­ dent-elect, noted that the so-called "invisible border" separating the U.S. and Canada is, in fact, very real. Conferences such as this one, she said, "help us discover and respect the in­ tegrity of that border." Still there is, at least as far as academic research is concerned, "continual free exchange of information across that border." Harrison said that she wishes there were a similarly free exchange be­ tween U.S. industry and U.S. academia. CIC president J. A. Morrison re­ marked that the world of science is universal, transcending national, ra­ cial, and cultural barriers. His words seemed to apply not only to the U.S.­ Canadian border but to the cultural barrier U.S. visitors saw signs of all over Montreal—that between En­ glish- and French-speaking Canadi­ ans. The Montreal meeting was some­ what lower keyed than ACS national meetings, not only in having fewer technical presentations and lower attendance (less than half that of the New Orleans meeting in March), but in not having a meeting of the ACS Council. The board of directors was

scheduled to meet after C&EN went to press. Among the highlights of the week's meetings was the conference banquet address by Dr. Russell W. Peterson, former head of the President's Council on Environmental Quality and now president of a newly formed public interest group called New Di­ rections. He discussed threats to world security and how they might be overcome with scientists' help. Four especially serious threats, he says, are the running out of the world's principal energy source, oil; plans to use plutonium as a power plant fuel; rapid worldwide escalation of armaments; and the growing con­ frontation between the have and have-not nations. "The public interests call for the people to develop a clear under­ standing of these threats and to de­ mand a change in the directions we have been [taking]," Peterson says. "Most of our leaders in business and government continue to make deci-

Chloroform precursors f< ind in natural waters

Concern over environmental matters has for some years provided one focus for chemical meetings, and last week's 2nd Joint Conference of the Chemical Institute of Canada and the American Chemical Society in Montreal was no exception. For example, new studies are adding to the store of information about potential "second-order" pol­ lution problems such as chlorinated hydrocarbons—particularly trihalomethane—formed during chlorination of drinking water. At the same time, attention is turning to treat­ ment strategies. Studying waters in the Great Lakes basin, chemists Barry G. Oliver and John Lawrence at Canada Centre for Inland Waters have found levels of chloroform precursors to be relatively low, and the Great Lakes water to be of "reasonably good" quality. In seeking the source of the precursors, however, they found that, in the nat­ ural waters studied, the main source is humic material. Man-made pollu­ tion apparently is not a significant source of precursors. Oliver and Lawrence also carried out lab studies on the effect of water Peterson: basic changes must be made treatment practices on trihalometh-

6

C&EN June 6, 1977

sions the same old way. Business leaders worry primarily about this year's operating statements and government leaders about the next election . . . . As a result we are being carried into the future by the mo­ mentum of the status quo—resisting change in every direction." Peterson urges scientists—and all citizens—"to try to influence the route our world travels. If we wait for someone else to do it, it is not going to happen." Obviously, Peterson says, "scien­ tists have a major role to play in shaping the world's future [but] to realize the progress we now recognize as necessary there must be some fundamental changes. An integrated, holistic, interdisciplinary approach is required that must be applied with humanistic wisdom—not with a simple application of blind technol­ ogy. To achieve this goal, basic changes must be made in our teaching of science and in our academic insti­ tutions themselves." Π

ane (mostly chloroform) levels. They find that filtration reduces less than 5% the precursors of the trihalomethanes that resulted from chlorination of their water samples. However, alum coagulation and flocculation followed by sand filtration removes about two thirds. Oliver cites published evidence that humic sub­ stances occur in aqueous solution as microcolloids. Thus, he says, alum treatment apparently removes the precursors by selective removal of humic materials. Most plants, Oliver points out, prechlorinate before alum treatment. But treating with alum first therefore could remove many of the trihalomethane precursors. Further evidence that such a treatment change might help comes from a study at the University of Louisville into water treatment pro­ cess modification. The university's Dr. John S. Zogorski notes, for ex­ ample, that changing the points of prechlorination at a Louisville treat­ ment plant has reduced chloroform concentrations 50%. Another approach to this problem is the use of ozonation as a pretreat-

ment to reduce the amount of chlo­ rine needed. Dr. Harvey H. Rosen of Union Carbide cites data from several studies by others showing that small doses of ozone are probably the most cost-effective way to reduce trihalomethane precursors. D

Levels of contaminants in water not hazardous The compounds that contaminate U.S. drinking water are not known to be health hazards at the concentra­ tions at which they are found in water, concludes an 18-month study of drinking water and health just re­ leased by the National Research Council. Nevertheless, uncertainties about the toxic and carcinogenic ef­ fects of many of these compounds dictate a cautious approach. The report, mandated by the 1974 Safe Drinking Water Act, reviews the data available on water contaminants and, where possible, proposes maxi­ mum safe levels for them. It is sup­ posed to provide a scientific basis for revising the primary drinking water regulations set up by the act. In almost every case, the report finds that information is lacking to establish a definite safe level for a contaminant. This is particularly true in the area of organic contaminants, especially those that may be carci­ nogenic. Here the report singles out 129 organic compounds, including 55 pesticides, for detailed examination. Of these, 22 are suspected carcino­ gens, either in animals or humans. The report estimates the human cancer risk based on lifetime expo­ sures for the 16 of these compounds for which data are available. Effects other than cancer also were evaluated for 45 compounds judged potentially toxic but not carcinogenic. For the latter group, where sufficient data are available, the levels found in water are substantially below the level likely to cause a hazard. Effects of other types of water contaminants also were assessed in the report. Some, such as radioactive materials, are at such low levels compared to natural background ra­ diation that their risk generally can be ignored, the report finds. Others, such as 22 inorganic materials, were found to be present at such low con­ centrations as to pose little or no threat to human health. However, the study does recommend re-evaluation of the present water standards for lead, arsenic, and selenium to increase the margin of safety now provided. Water treatment practices greatly reduce the incidence of disease caused by waterborne microorganisms, the

Organics In drinking water are below safety levels Maximum observed concentration in water, microgram/titer

Suggested no adverse effect revels iit water, microgram liter Estimate 1 * Estimate 2*

2,4-D

0,04

87.5

4.4

Alachlor

2.9

700.0

35.0

Butachtor

0.06

Paradichlorobenzene

6.0 1.0

70.0 7

3.5

Hexachforobenzene Atrazirte

5.0

150

7.5

Di-n-btityl phthalate

5.0

770

38.5

30,0

4200

Di(2-ethyl hexyl)phthalate Hexachlorophene

0.01

Methyl methacrylate

1.0

Pentachlorophenol

14

Styrene

1.0

f ί f

93.8

0.35 4.7

210

7 700

0.35 35.0

21 931

46.5

105

a Suggested levels are based on human adults weighing ?0 kg who have an average daily intake of 2 liters of water. Estimate 1 assumes 20% of total acceptable daily intake of the ohemloai in question comes from water. Estimate 2 assumes 1 % of total acceptable daily Intake comes from water.

report states. Chlorine has been the main disinfectant. Concern had been raised by other studies that chlorine, added to water to combat microor­ ganisms, might be reacting with or­ ganic contaminants to form possibly carcinogenic organochlorine com-

pounds. However, in 1975 alone, more than 10,000 cases of waterborne en­ teric disease were reported. This health hazard must be weighed against the possibility of forming carcinogens when evaluating the ap­ propriateness of chlorination. D

HEW panel recommends improvements for FDA Although the Food & Drug Adminis- I tration is neither pro- nor anti-in­ dustry, and its new drug approval system "is fundamentally sound," there is room for "substantial im­ provement," an independent review panel has concluded. Set up more than two years ago by the Depart­ ment of Health, Education & Wel­ fare, FDA's parent, the panel last week released its final report on agency "troubles" that began in the late 1960's and early 1970's. The panel and this final report are the result of allegations by FDA employees in 1974 before a Senate health subcommittee chaired by Sen. Edward M. Kennedy (D.-Mass.) that FDA was dominated by the drug in­ dustry. Chaired by lawyer Norman Dorsen of the New York University school of law, the panel singles out four areas for improvement in the way FDA functions, including: Open FDA's drug review process to public scruti­ ny; increase the agency's scientific facilities; improve standards for ap­ proval of drugs, and increase FDA's authority over drugs already mar­ keted. To this end, the report lists seven basic recommendations. Foremost is the suggestion that Congress rewrite the Food, Drug & Cosmetic Act so that scientific data submitted to FDA would be made public. To a large ex- |

tent this would end trade secrets, though the panel suggests a provision that such data may not be used by a drug sponsor's competitors to support a competing drug application. In addition, the panel recommends that FDA consider risks and benefits in passing on new drug applications. The current requirement that drugs must be shown "safe" and "effective" is "imprecise," according to the re­ port. FDA also should contract for independent spot checks of any ani­ mal testing data the agency believes to be incomplete or misleading. At the same time FDA also should take a look at the feasibility of large-scale independent clinical (human) testing of new drugs. Clinical testing now is conducted by drug firms. The internal mechanics of FDA also are addressed by the panel re­ port. For example, the panel says that the agency should develop a profes­ sional training program for its staff and relocate on a single, wellequipped campus which has adequate research and library facilities. In dealing with pharmaceutical firms, the panel believes the agency should adopt uniform rules governing communication between pharma­ ceutical firms and the FDA staff, and written correspondence should be the preferred form of contact. Reaction to the panel's conclusions is mixed. The Public Citizen Health June 6, 1977 C&EN

7