Panel Discussion: Analytical Chemistry-Toxicity Testing Interface

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 10, 2018 | https://pubs.acs.org Publication Date: December 15, 1986 | doi: 10.1021/ba-1987-0214.ch037

Panel Discussion: Analytical Chemistry-Toxicity Testing Interface Edited By I. H. (Mel) Suffet (Chairman) and the Panelists S U F F E T : We have the itinerant experts on this podium who have brought to us the problem that the analytical chemists are going to face: What are the best schemes to adapt for concentration of trace contaminants i n water and waste water systems? Is it a broad spectrum approach to determine everything that is present, based upon many different isolation methods? Is it an approach to determine everything in a sample as the Master Analytical Scheme proposes? Is it an approach to select specific chemicals for quantitative analysis as priority pollutants? C a n it be that some combination of these is the best? The basic question is, what is the best use of analytical chemistry i n making judgments about the safety and the quality goals for drinking water? Phase transfer processes describe the different methodologies that we have available for isolating samples for each of these methods. W h i c h methods are best? A focus of attention is the priority pollutant concept that the U S E P A [U.S. Environmental Protection Agency] uses. Does the European community agree with the priority pollutant approach? I have selected a c o m p o u n d , X , to consider. This compound is present i n water and it is not a priority pollutant. This is my favorite compound because it is the compound that is in the water, but we do not k n o w anything about its toxicology yet. If we are going to consider broad spectrum analysis for the general isolation-concentration method, how do we handle it? N o w that the background for the discussion has been developed, I w o u l d like to begin b y asking the panel, do we analyze only for specific compounds or d o w e develop a multiple compound protocol? This could be addressed from the analytical and toxicological viewpoints. G U R K A : W e l l , the specific compound approach obviously wastes most of the information available in the extract. I mean it is b a d enough now that the U S E P A only considers about 126 priority pollutant com0065-2393/87/0214/0763$06.00/0 © 1987 American Chemical Society

Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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pounds of the G C [gas chromatographic] volatile fraction, and yet the G C volatile fraction is only 5% or 10% of the total solvent extractables. That leaves open the question of h o w we do it, but most of the information about the extract is being wasted. That's perfectly obvious. P I E T : T o approach this, we probably have to do it in both ways: First, set out the specific compounds that are of great consequence to the environment in its entirety including air, water, and sediment. These might be called real priority pollutants that endanger not only humans but also the environment and the ecosystem itself. So let's find these specific compounds. We have often seen that specific effects are caused b y some specific compounds. S U F F E T : Y o u are referring to things such as v i n y l chloride, a k n o w n carcinogen to humans? P I E T : Yes. S U F F E T : The dioxin isomers, for example? P I E T : Yes, dioxins are compounds that we have not yet identified to cause a specific p r o b l e m , but w e are quite sure that we w i l l find them responsible for problems. O n the other hand, there is the broad spectrum component approach. The component approach is best used to compare environmental systems with each other and to see the extent of pollution or h o w it may be decreased. W i t h the broad spectrum approach, we want to interface the presence of effect-causing compounds, which might not be a substantial part of the extract, with the presence of other industrial compounds in the extract. B U L L : W e l l , it seems silly to me to consider neglecting what you can easily analyze chemically. Y o u easily analyze for certain chemicals, and these tend to be the volatile and relatively nonpolar chemicals for which there is a lot of available toxicological information. This does not mean that because you are worried about the whole mixture, you discard what you k n o w about the individual compounds. S U F F E T : But those individual compounds, like the volatiles, which are not very difficult to isolate and collect, do you put them back into a reverse-osmosis extract of a broad spectrum of compounds before you give them to the animals? B U L L : N o , I w o u l d not. I definitely w o u l d not. I w o u l d test those separately, because there is no point in cluttering up an experiment that is already cluttered. What I w o u l d really like to see as a bottom line is to deal with those volatile compounds that are usually poorly concentrated b y most concentration methods on the basis of what you k n o w about them. That's where the bulk of the toxicological information is available already. Y o u can do a combined experiment using those, if you like, if you can't deal with them on the basis of what you k n o w about them



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individually. However, compounds such as trichloroethylene, tetrachloroethylene, chlorinated benzene, etc. have received a lot of study individually. What really is the issue, I think, is the material that has yet to be dealt with analytically. I tend to think these are the polar materials. It doesn't make sense, for example, to run an Ames test on benzene. You already know benzene is a carcinogen. You do not need to run an Ames test on benzene to deal with benzene in drinking water. The information that you don't have, which bioassays of the concentrate will partially give you, is the information on that fraction of the material that is in the water that you can't deal with analytically by more traditional means. S U F F E T : Well, something like electrophilic materials, the ones I think of are the epoxides: How would you concentrate them? They are not very stable in the laboratory by known concentration methods. Do we know if they're destroyed during sampling? Has anybody tested this? Has anybody taken a series of or should we take a series of these very difficult to analyze electrophiles and put them through the broad spectrum isolation procedures for testing? TABOR: At the USEPA Workshop at Palo Alto, California, in July 1984 [see chapter 2 of this book], it was suggested that every one of the six isolation protocols recommended would be tested with surrogate compounds to validate the procedures, and Dave Brusick of Litton Bionetics and some of the other biologists in the group were talking about lists of compounds on the priority pollutant list and others to reflect compounds with and without known mutagenic activity. B U L L : You're really referring to direct-acting carcinogenic compounds for the most part, the unstable or reactive electrophilic compounds. S U F F E T : I think this audience would appreciate it if you explain the difference between the two types of compounds that are carcinogenic. B U L L : Okay, certain compounds require metabolic activation to electrophilic intermediates, and the others are electrophiles themselves. Both types of compounds can be carcinogenic. Presumably, the latter group [electrophiles] would be the ones that would be destroyed by the concentrating methods. The worry would be that nucleophilic material in the concentrate could react with the electrophiles and destroy them as you concentrate the samples. This would be proportional to the amount of compounds present and the degree and method of concentration. Ultimately, you can expect them to disappear. Most of our evidence comes from model studies on chlorination byproducts. This is the major source of electrophilic chemicals in most drinking waters. The situation, however, may be different in industrial



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or other types of waters. Those compounds seem to survive the concentration procedure, at least to the extent that we have been able to deal with that. I think Jack Loper s data on the mutagenic activity of extracts collected b y reverse osmosis at the cities in the five-city study support the idea that at least those compounds that you recover are fairly stable yet pretty active mutagenic compounds. A U D I E N C E : What do y o u do about compounds that are not direct-acting mutagens? I a m talking about compounds that are probably in drinking water and that might be tumor promoters yet w o u l d not be active in the Ames test. B U L L : This is one of the reasons I was presenting the argument that you have to do whole animal studies not only to judge the degree of hazard but to deal with the many factors that can m o d i f y the impact of a mutagenic chemical in the whole animal. Those toxicologists who tend to be generalists are reluctant to use the Ames tests and the shorter term tests for carcinogenesis because there are many toxicological hazards that they are not capable of dealing with at all. I d i d not get a chance to develop that argument as w e l l as I w o u l d have liked. I see the short-term carcinogenic test as not particularly useful in judging hazards associated with a particular water. I see it very useful in telling me something about the variability of that water. I think at this stage of the game I do not see any other alternative but to go to real animal studies to try to judge the relative risk of this source of water versus a source of water that is already deemed to be acceptable. N o t only do y o u have to worry about the tumor promoters, as y o u pointed out, but you also have to worry about renal effects, hepatotoxic effects, etc. These kinds of effects have been associated with those chemicals that have been identified in water just as much or even more so perhaps than carcinogenesis. L O P E R : I have a question for Cotruvo. I think that one thing strictly f r o m the bioassay point of v i e w (and that comes d o w n to being 9tZ Ames test data) is that there is a logical approach f r o m the practical point of view of using Ames test data. I agree, as Bull iust said, the assay does not see a lot of toxicological end points, but for better or for worse, I think w e cannot ignore the fact that w e are still on the dilemma of the relative importance of threshold versus nonthreshold effects; we are living with the recognized concern about compounds that might have a 5-30-year time in terms of latency for cancer. So you are dealing with a toxicology problem for compounds that have genotoxic effects with long-term gestation periods versus compounds that we approach classically as short-term toxicants, where we can define the functional nonthreshold effect. We are not going to solve this problem today, but I do not think w e can get away from the issue b y wishing it away. The Ames test



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remains highly predictive for a large percentage of compounds that are k n o w n to be carcinogenic, and the reality is that the data w i l l be there and y o u w i l l have to find a w a y to deal with it. When w e started our work, the state-of-the-art collection method of reverse osmosis was used to screen a number of toxicological parameters; it is the nature of the biology we deal with that the Ames test was found to develop reproducible data at a l o w cost and in a time frame that was less than most of the other toxicological tests. So, if w e set up a comparison of short-term screening-test studies, it w i l l generate the same k i n d of hard numbers for mutagens that somehow you w i l l have to deal with. I agree with what Bull said with respect to his first two major points; namely, if y o u focus on water reuse as in the Denver program, you want to consider the source of the water and then, secondly, the actual levels of the k n o w n toxicants. If N e a l were here I think he w o u l d say, "Let's study those compounds that are at high level—identify them and see if they're toxicants in any of the likely biological end points, and set your standards that w a y . " Finally, when looking at water of different types, we have a problem of deciding, what is the appropriate sample? I think one can divide water into four areas f r o m the mutagenicity data. One is the water source that is clearly industrially contaminated with compounds that we should find out more about. Second, there is an area that involves surface water where waters can be affected b y industrial problems of specific chemicals, which we should k n o w more about, but we do not really k n o w which sample to take and h o w often the compounds might be there because of variability of discharge. Then, there is a third category, which is water that is not frequently affected b y chemical toxicants, but it has a high T O C [total organic carbon] level and T H M F P [trihalomethane formation potential]. This type of water introduces all of the problems that we have been dealing with under the T H M regulations. The Ames test w o u l d assist in determining w h i c h disinfection process to use. What do w e do about the water that shows mutagenic activity as a result of chlorination? I think that the presentation of Baird [see chapter 31 of this book] speaks about what those compounds might be, not b y name, but b y property. Finally, m y p r o b l e m , Cotruvo, is I think really w e are going to f i n d that w e are going to be looking more and more at ground water, partly because of social reasons and partly because of questions that we do not have answers for. I think ground water is going to be such a heterogeneous, locally determined problem that I do not k n o w what your ideal sample is. I think w e w i l l have to focus on a priority procedure that goes through the major chemicals. F r o m the biological side, of less priority are the TA100 mutagens that are not active in the presence of S9 or the



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compounds that turn over TA100 in the absence of S9 and are decreased in the presence of S9. O f more concern are the S9-dependent compounds active for either 98 or 100. Those are implied to be industrial chemicals. I think those w o u l d be the logical mutagens to pursue on a nameby-name basis. T h e n go to Ames testing for toxicological assessment, setting limits, whether they are industrial outfalls or whatever; then, having removed them f r o m the problem, you can look at the other category that I described, for example, the question of chlorination byproducts in the absence of those industrial compounds. But, to pick a representative sample and then try to deal with ground water contaminants of different types across different parts of the country, I think that is a question we have not addressed. That is an area where a lot of the analytical chemistry w i l l have to go on for, unfortunately, much too long. S U F F E T : A l l right. Thank you, Loper. I appreciate you taking over because you summarized this problem very nicely. C O T R U V O : I think you d i d summarize the problems very well, L o p e r , and I think I agree with all of the points y o u raised. I guess the point I was making in m y paper was that we have a small number of choices available to us in terms of what to do in the event that an unacceptable contamination is found. We have a small number of engineering and economic choices. So it really then becomes a question of what are the circumstances that lead you to make the choice of O p t i o n A , Option B, or Option C in terms of your public water supply. I think the precise definition of those circumstances is never going to be achievable, but we perhaps could arrive at some set of qualitative principles that w o u l d be used to allow one to make a choice in a given case, for example, this water, because of its source and its history, needs a certain k i n d of treatment applied to it so that there w i l l be the m i n i m u m possibility of undesirable chemicals being present in the finished water. N o w , we w o u l d not k n o w exactly what each one of those chemicals might be, but our bottom line conclusion would be less is better, and the object is to perhaps take the Sontheimerian approach. His point is very simple: to treat the water to try to approach the quality. S U F F E T : O f ground water. C O T R U V O : O f what you w o u l d acknowledge to be good quality ground water. S U F F E T : Right. C O T R U V O : The ground water is set as being ideal, one that is uncontaminated b y industrial activities. So, in the case of ground water, as an example, I w o u l d answer your last question b y picking out a representative contaminated ground water. I would try to pick a representative clean ground water as the primary standard. Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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Then I w o u l d deal with it on a chemical-by-chemical basis because really it is a much simpler problem. I mean, traditionally, when one finds a contaminated ground water, one finds 1 or 2 or 5 or 12 or maybe 50, but not 500 or 700 or 900 chemicals. So really that ground water has already undergone some level of treatment b y the fact that it is ground water. It has undergone certain biological and chemical processes. Therefore, one can deal with a smaller problem. One can try to pick those substances that are most likely to be the toxic ones and establish limits for those, just as we do n o w b y proposing M C L s [maximum contaminant levels]. But, I guess m y bottom line is there is a great amount of methodology that has been developed both for concentration and for assessments of hazard. A l l of those methods of in vitro and in vivo assessment procedures are available. There should be some way of establishing a multiple-tier testing system that w o u l d allow one to go through those procedures to apply to these concentrates, ultimately arriving at the whole animal bioassay. By these means and b y using representative sampling of water types around the country, one could then arrive at the matrix that would lead one to relate source type to quality goal and appropriate treatment in between to achieve the quality goal. Then one can apply that matrix in the other cases that have not been tested b y the complete testing routine using the rapid techniques for analyzing what one w o u l d anticipate in the nonsophisticated test procedure that was discussed. There has been a lot of development work done on all of these techniques, both in concentration techniques and the toxicological methodology. A lot of it has been done b y you and b y our people in the water laboratories and in the toxicology laboratories in Cincinnati. So the proposal is, let's put this all together. Let's start applying it. Let's make some decisions while we are doing more detailed mechanism work. I think we are ready to start putting it together and making some decisions to i m prove water quality where it is obviously needed. S U F F E T : I w o u l d like, while we are on this line of thought, to say there is an alternate proposal which is related to reuse of water. I and some people in the audience such as Kopfler and Bull of U S E P A are associated with the Denver Water Department reuse work. Denver is going to treat its waste water for drinking water reuse, and 10% of the water supply is intended to be reused waste water. They have come up with an idea or a protocol for a decision on the basic question: Is this reuse water safe to drink? A n d their idea is very simple. O n the one hand, Denver has its normal drinking water; they w i l l subject it to all the testing possible. O n the other hand, Denver has its reuse water; if they subject it to the same tests, and the reuse water is no worse than the drinking water that the people normally get, they w i l l consider it to be acceptable for drinking. What is the comment from the audience or the panel about that type of proposal? Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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C O T R U V O : W e l l , there is one basic premise, and that is that your normal water is a good quality water. I mean y o u are obviously not trying to compare the water unfairly. S U F F E T : That is their premise. A U D I E N C E : It is true some years ago w e had recycled water in Dallas, and it was of highest quality or higher quality than the drinking water for the city of Dallas. However, the discussion was related to the propriety of tests to be run on the reuse water. T h e design and type of test used for drinking water are different than tests that have yet to be developed for recycled water. A n d the area that w e directed our attention to at the time was the area of biology. W e detected several viruses in the recycled water that were not detected in the drinking water. S U F F E T : So, on the basis of comparative chemical tests, the reused water was judged to be of higher quality. But, this was not the case for viruses. A U D I E N C E : Chemically yes, because the argument was that the tests used to evaluate the quality of water f r o m a chemical point of v i e w are the same, but not f r o m a bacteriological point of view. S U F F E T : In the Denver project, they are also looking at the bacteriology and virology f r o m this same viewpoint. In virology, you do not k n o w all the organisms, and y o u have not identified them. We had the unfortunate situation in Philadelphia many years ago with the Legionnaires* disease where we d i d not k n o w about the organism Legionella. There are a lot of organisms that are present that we do not k n o w about, and in this respect there is a definite similarity between virology and the trace chemicals that w e do not k n o w about. P I E T : There is some information f r o m Europe, for instance, on the Rhine River in Germany. I k n o w that there are many b i g cities in Germany and also in our country where water is purified b y bank infiltration f o l l o w e d b y some ozone treatment; that is a good system and leads to an excellent quality in terms of bacteriology. What w e always try to avoid is chemical treatment of water. In fact, w e use chlorination only as a safety measure to have some hygienic control in the distribution system. Yet, when the organic content of the water is even as l o w as possible, preferably 1 m g of total organic carbon per liter (not more), and you use chlorination, y o u increase the mutagenicity. That is well-known. Y o u also increase the adsorbable organic chlorine (AOC1), which is difficult to remove, even b y ozone and b y bank filtration. Thus, quite a bit of unidentified polar compounds is introduced into drinking water, which you can measure with A O C 1 and which could have some health effect, and that is the reason w h y we avoid chlorination even before bank filtration.



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According to the theory of Zoeteman, the taste perception of water is a very good method of local control. W e had taste tests carried out in Rotterdam, the Hague, and other b i g cities b y the so-called consumer panels—not trained people, just consumers—and we let them rate the taste of the water. W e l l , w e w o r k e d it out statistically and showed that the method was excellent. N o w w e polish the water treatment methods on the basis of taste perception. It is not expensive. It works quite well. S U F F E T : Y o u are bringing up two interesting points: one that Loper referred to, that is, using treatment techniques as a method to control the contaminants and then testing before and after each treatment to see differences. M a y b e the best application of Ames testing and other toxicity testing w o u l d be on a difference basis, before and after a process. Is there a difference? Is it less? Is that an approach that can be used, especially in treatment situations, where industrial wastes are potentially present in drinking water? W o u l d anybody on the panel like to make a comment about that? B U L L : I w o u l d subscribe to that to some extent, but you are not going to be able to conduct a 2-year bioassay at each plant and each and every treatment process at every water treatment location in the country. So I think that this is where the problem arises, and you require a reasonable time resolution in your analysis. T o deal with a day-to-day problem, the short-term tests are appropriate. As the state of the art in toxicology exists today, I think the only practical application of the long-term or lifetime studies for cancer as w e l l as other end points is a comparison with an acceptable source of drinking water as Cotruvo suggested, or as is being proposed for the Denver project. The most you can hope for is a demonstration that that water is as safe or safer than an acceptable source. S U F F E T : Considered acceptable, but with no toxicological data to say it is acceptable. B U L L : That is what I am saying. That is where y o u confine your long-term testing. Y o u cannot do long-term testing on every water sample y o u might like to collect. However, at present and for the foreseeable future, these studies are the only thing that is going to allow y o u to deal with relative risk. Y o u can use the shorter term test to do the k i n d of thing y o u are referring to because they have the time resolution, but you need to deal with them at that level and recognize their limitations. C O T R U V O : That is the control. J U N K : I am a chemist. I am not a toxicologist. I am going to discuss something out of m y field and with complete ignorance. I want to draw an analogy. Thinking in terms of the tremendous difficulties associated with the identification of pathogenic organisms, what d i d people in the drinking water supply industry do several years ago? They finally came u p — a n d I think maybe I am agreeing with C o t r u v o and maybe I a m



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not—with a simple test of the number of the fecal coliform, and they are still using it today. We do not test for Legionnaires' disease, and every so often something unfortunate comes up like that. But b y and large, the fecal coliform test protects us f r o m pathogenic diseases. The question is, is there something like a mutagenicity test, direct acting or indirect acting, whereby w e can test and determine the risk and set an acceptable level for our drinking water supply? I w o u l d consider an acceptable level toward humans and an acceptable ecological level. M a y b e there is a single test or maybe a battery of simple tests. I think C o t r u v o was saying, let's put all of our knowledge together now and see if w e can't come up with those simple tests for a number of different water supplies where w e can decide whether we have an acceptable risk level without trying to decide whether this water is better than that water, because as soon as y o u try to decide that, what are your criteria? N o w , at the same time, I think w e should not ignore the fact that we need whole animal tests and w e need tests of specific chemicals. In the same sense, and I w i l l draw the analogy to the bacteriologists. They don't ignore everything else and just say fecal coliform is it. W e still need to continue to determine the risk associated with specific chemicals and then the whole combination of those specific chemicals. Finally, synergism is not always positive. Sometimes it is negative, and w e are never drinking pure water. W e are always drinking, even out of the ground, a mixture of chemicals. Sometimes that mixture of chemicals is good for us, and sometimes that mixture of chemicals is b a d for us. B U L L : I only have one problem with what you said, Junk, and that was when y o u attempt to judge the level of risk using the Ames test results. Y o u cannot compare this water with that water. I do not think there is any w a y that we are going to deal with risk with the Ames test or use it in any k i n d of absolute terms n o w or in the future. I think the only thing you are going to be able to do is use it in a relative sense to judge the effectiveness of a treatment process within a plant. It w i l l not serve as a standard that can be applied nationally in any meaningful way. S U F F E T : A l l right. A relative sense. J U N K : Agreed, agreed. S U F F E T : I want to get this clarified. Y o u are saying that the Ames test can be used to measure differences before and after a process in a relative sense, and you are saying that you cannot judge risk b y the Ames test? B U L L : That is right. I do not think you can. S U F F E T : But, by the fecal coliform method, can you judge risk? B U L L : N o . T o quibble a little bit with the fecal coliform situation, you have, I think, a different situation. Y o u have a fecal coliform test, Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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which is really telling you h o w effective your treatment has been in terms of killing bacteria and inactivating viruses. You k n o w that if the treatment has been effective, there should be no fecal coliform. It is a fairly universal thing. N o single chemical w i l l represent the ability of a treatment process to deal with all chemicals. Therefore, the Ames test does not even have the simple utility of the fecal coliform test. However, very few people w o u l d argue that drinking water should contain as few mutagens as possible. In addition, I do not think you have the luxury that chemical problems are necessarily going to be dealt with effectively b y only a single type of treatment process that is analogous to disinfection with fecal coliforms. The other problem is that probably the major source of mutagens in most drinking water comes from one of the treatment processes. J U N K : But, was that not Cotruvo's point, whether w e should treat the water further to make it acceptable or not? The comments I made were within the realm of deciding whether you should treat the water to get it d o w n to an acceptable level or not. In the same sense, with fecal coliform, they finally decided on chlorination. Yet, there w o u l d be the European community, in particular, that w o u l d say chlorination really is not the w a y to go; ozone is. Those arguments w i l l still be there. S U F F E T : The European community uses ozone as an alternative to chlorine, and I personally have a problem with the thought process that ozone does not produce other chemicals that might be as toxic or carcinogenic as those produced b y chlorination. A t present, w e do not have good analytical methodologies to identify those ozonation products. So that is m y basic difference with the European thesis in terms of using ozone and not too much chlorine. I want to make one other appropriate comment, and that is the Ames test could be considered as a nonspecific analytical methodology. Really, that is what w e are talking about. N o w , Piet mentioned something like organic chlorine as a nonspecific chemical parameter. So the question is, should w e go after something like organic chlorine, oxygenated compounds, total epoxides, total something or other, to try to get some correlations here with the specific compounds and develop this correlation? You also mentioned taste and odor, a subject near and dear to m y heart because I have been working in that field. I think the human species is very intriguing in that we do not drink water that does not taste good. There is some background to the history of h o w humans developed as a race and h o w they were able to protect themselves b y using their noses. M a y b e that w o u l d be some type of correlation that could be developed. But this is something that has to be looked at. What about the use of these nonspecific parameters? I k n o w Cotruvo and I have had some go-arounds on organic chlorine as a methodology in the past. What does the panel think about that? Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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P I E T : T h e nonspecific parameters are used in local and regional control applications. They are probably not general control parameters but more associated w i t h local and regional problems. I think w e definitely can use these parameters, and they are very fast. Another thing is what y o u just mentioned, that many contaminants are not analyzed according to standardized analytical procedures. That is one of the biggest problems, of course. F o r water treatment methods, w e do not prefer the chemical treatment methods but the physical treatment methods. Thus, w e are trying to remove things and not to introduce things. This is important. That is our philosophy. There is another approach that is quite opposite to this one. Water has to be, according to the W H O [World Health Organization] recommendation, wholesome and agreeable. W e are always dealing with b a d things, but w e do not k n o w so much about good things. W h y does water taste poorly, w h y is it agreeable? When w e make water with only minerals, it is not real tasty water; it is not agreeable. There are some agreeable organic compounds present in ground water. W e have tried to analyze the compounds with a nice flavor. Water treatment plants, however, do not apply flavoring to the water. S U F F E T : Y o u can also a d d vitamin C , I have heard. P I E T : W e l l , adding things is a matter of controversy in our society. When good things, however, are not in a system, then there might be something w r o n g in that system. When good things disappear f r o m a system—that is also true with the ecosystem—there is something out of balance in the system. A n d that is also in water. W h e n the tasty compounds disappear f r o m water, there is something out of balance. A n d that is the same, for instance, in the soil and its ecosystem. When soil is polluted, y o u see some changes in the ecosystem. Y o u can try to measure this, for instance, b y determining h o w microorganisms are affected. I think that is a nice approach; see w h i c h good things are in systems, and in the case that these good things disappear, find out w h y they disappear. S U F F E T : Cotruvo, d o y o u have any comment about the nonspecific idea? C O T R U V O : W e l l , I think their primary application is probably in the area of process control. About taste and odor, I do not k n o w what one can d o on the positive side, but obviously there is concern on the negative side. If one develops adverse tastes, they should be removed. But for things such as T O X [total organic halogen] or other group, a parameter w o u l d be useful in evaluating the process that is being used to improve the quality of water and to demonstrate that, in fact, components are being removed d o w n to some desirable level. There may not be any direct correlation between toxicology and that level, but that level may be chosen strictly on the basis of engineering principles and common sense, and that is a positive step. Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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S U F F E T : C o m m o n sense is the most positive thing, if it is used. C O T R U V O : Occasionally, it is. B U L L : Cotruvo made m y comment for me to a large extent, but one of the things I w o u l d like to challenge this group of chemists with is the fact that many of the compounds we are dealing with in the mutagenicity area are electrophiles. Electrophilic compounds seem to be what w e are measuring after disinfection, that is, the production of direct-acting mutagens. A very useful parameter that w o u l d tend to take the results a little out of the emotional realm w o u l d be a measure for electrophilic compounds, that is, total electrophilic compounds. That should be easy enough to do with these presumably direct-acting materials. There could be a standard method using nucleophilic trapping agents. S U F F E T : The problem is the concentration of the materials and the test at that l o w concentration. That is the major problem. B U L L : That is the major problem, but f r o m an analytical standpoint, I do not think that is an impossible problem. S U F F E T : W e l l , the analytical chemists w i l l tell you nothing is i m possible. The water treatment people say we can treat anything. So I think it is a challenge for the analytical chemists to come up with a test like that. Albert C h e h came up with some methods to look at change in color using the epoxide as an idea, but it has never been followed through and it has never been done in contaminated systems. B U L L : The other thing I w o u l d like to do is reinforce what Cotruvo said about the use of surrogate methods in process control. I think they are probably very useful in a situation where you know what is going on. But when you are trying to take a T O X measurement, w h i c h might include anything f r o m dioxin in one sample to trichloroethylene in another, the meaning of that T O X result is entirely different in the two circumstances. S U F F E T : This enthusiasm is great! I w o u l d like to thank the panelists. I think they d i d a very nice job in presenting different viewpoints about the subject, and I thank the panelists and the audience for putting the presentations into a framework. R E C E I V E D February 3,1986.


Panel Discussion: Analytical Chemistry-Toxicity Testing Interface

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