Showing papers by "United States Environmental Protection Agency published in 1987"

Ecoregions of the Conterminous United States

Abstract: A map of ecoregions of the conterminous United States has been compiled to assist managers of aquatic and terrestrial resources in understanding the regional patterns of the realistically attainable quality of these resources. The ecoregions are based on perceived patterns of a combination of causal and integrative factors including land use, land surface form, potential natural vegetation, and soils. A synoptic approach similar to that used to define these ecoregions is also useful for applications of the map. Initial efforts to use the framework are at the state level of resource management; they center on aquatic ecosystems — mainly attainable ranges in chemical quality, biotic assemblages, and lake trophic state.

Lung cancer and indoor air pollution in Xuan Wei, China

Abstract: In Xuan Wei County, Yunnan Province, lung cancer mortality is among China's highest and, especially in females, is more closely associated with indoor burning of "smoky" coal, as opposed to wood or "smokeless" coal, than with tobacco smoking. Indoor air samples were collected during the burning of all three fuels. In contrast to wood and smokeless coal emissions, smoky coal emission has high concentrations of submicron particles containing mutagenic organics, especially in aromatic and polar fractions. These studies suggested an etiologic link between domestic smoky coal burning and lung cancer in Xuan Wei.

The 1986 Lake Nyos Gas Disaster in Cameroon, West Africa

Abstract: The sudden, catastrophic release of gas from Lake Nyos on 21 August 1986 caused the deaths of at least 1700 people in the northwest area of Cameroon, West Africa. Chemical, isotopic, geologic, and medical evidence support the hypotheses that (i) the bulk of gas released was carbon dioxide that had been stored in the lake's hypolimnion, (ii) the victims exposed to the gas cloud died of carbon dioxide asphyxiation, (iii) the carbon dioxide was derived from magmatic sources, and (iv) there was no significant, direct volcanic activity involved. The limnological nature of the gas release suggests that hazardous lakes may be identified and monitored and that the danger of future incidents can be reduced.

The bioavailability of sediment-sorbed organic chemicals: A review

Abstract: Xenobiotic chemicals that are present in aquatic environments are typically concentrated on suspended particles and sedimentary materials where they represent a source of chronic contamination to benthic and pelagic organisms. Laboratory and field studies of bioaccumulation, toxicity, and food-chain transfer of chemicals bound to sediment have shown the potential ecological impacts that may result from the contamination of sediments. In this review, the chemical and physical processes that determine the environmental fate of sediment-sorbed organic chemicals are outlined, and their relationship to bioavailability is discussed. Methods currently used to predict the fate of pollutants in the aquatic environment are of limited use for the assessment of sediment-sorbed chemical bioavailability because they are based on the compound's behavior in the water column. Furthermore, an organism's morphology and ecological niche can profoundly affect its ability to accumulate xenobiotic chemicals from sediments and these must be considered before the populations at greatest risk can be identified.

Efficiency of kriging estimation for square, triangular, and hexagonal grids

Abstract: Although several researchers have pointed out some advantages and disadvantages of various soil sampling designs in the presence of spatial autocorrelation, a more detailed study is presented herein which examines the geometrical relationship of three sampling designs, namely the square, the equilateral triangle, and the regular hexagon. Both advantages and disadvantages exist in the use of these designs with respect to estimation of the semivariogram and their effect on the mean square error or variance of error. This research could be used to design optimal sampling strategies; it is based on the theory of regionalized variables, in which the intrinsic hypothesis is satisfied. Among alternative designs, an equilateral triangle design gives the most reliable estimate of the semivariogram. It also gives the minimum maximum mean square error of point estimation of the concentration over the other two designs for the same number of measurements when the nugget effect is small relative to the variance. If the nugget effect is large (.90 σ 2 or more), and the linear sampling density is >0.85r where r is the range, the hexagonal design is best. This study computes and compares the maximum mean square error for each of these designs.

Exposures to Benzene and Other Volatile Compounds from Active and Passive Smoking

Abstract: Personal exposures and breath concentrations of approximately 20 volatile organics were measured for 200 smokers and 322 nonsmokers in New Jersey and California. Smokers displayed significantly elevated breath levels of benzene, styrene, ethylbenzene, m + p-xylene, o-xylene, and octane. Significant increases in breath concentration with number of cigarettes smoked were noted for the first four aromatic compounds. Based on direct measurements of benzene in mainstream cigarette smoke, it is calculated that a typical smoker inhales 2 mg benzene daily, compared to 0.2 mg/day for the nonsmoker. Thus, cigarette smoking may be the most important source of exposure to benzene for about 50 million citizens of the United States. Passive smokers exposed at work had significantly elevated levels of aromatics in their breath. Indoor air levels in homes with smokers were significantly greater than in nonsmoking homes during fall and winter but not during spring and summer. The average annual increase in homes with smokers was 3.6 microgram/m3 for benzene and 0.5 microgram/m3 for styrene--an approximate 50% relative increase in each case. Thus, exposure to benzene and styrene may be increased for the approximately 60% of children and other nonsmokers living in homes with smokers.

Blood Lead, Hearing Thresholds, and Neurobehavioral Development in Children and Youth

Abstract: NHANES II audiometry data were used to confirm a previously observed link between blood lead (PbB) level and hearing threshold. Other indicators of neurological development, such as age at which a child first sat up, walked, and spoke, and the presence of speech difficulties and hyperactivity were also examined to determine if they were significantly related to lead exposure. The probability of elevated hearing thresholds at 500, 1000, 2000 and 4000 Hz increased significantly (p < .0001) with increasing PbB for both ears. PbB levels were also significantly related to delays in the age at which children first sat up, walked, and spoke and to the probability that a child was hyperactive. Lead was not related to the probability of a child having a previously diagnosed speech impairment.

Fish acute toxicity syndromes and their use in the QSAR approach to hazard assessment.

Abstract: Implementation of the Toxic Substances Control Act of 1977 creates the need to reliably establish testing priorities because laboratory resources are limited and the number of industrial chemicals requiring evaluation is overwhelming. The use of quantitative structure activity relationship (QSAR) models as rapid and predictive screening tools to select more potentially hazardous chemicals for in-depth laboratory evaluation has been proposed. Further implementation and refinement of quantitative structure-toxicity relationships in aquatic toxicology and hazard assessment requires the development of a "mode-of-action" database. With such a database, a qualitative structure-activity relationship can be formulated to assign the proper mode of action, and respective QSAR, to a given chemical structure. In this review, the development of fish acute toxicity syndromes (FATS), which are toxic-response sets based on various behavioral and physiological-biochemical measurements, and their projected use in the mode-of-action database are outlined. Using behavioral parameters monitored in the fathead minnow during acute toxicity testing, FATS associated with acetylcholinesterase (AChE) inhibitors and narcotics could be reliably predicted. However, compounds classified as oxidative phosphorylation uncouplers or stimulants could not be resolved. Refinement of this approach by using respiratory-cardiovascular responses in the rainbow trout, enabled FATS associated with AChE inhibitors, convulsants, narcotics, respiratory blockers, respiratory membrane irritants, and uncouplers to be correctly predicted.

Lead and child development

Abstract: A group of independent epidemiological studies shows that fetal exposure to levels of lead previously considered safe is linked to impairment of infant mental development.

Studies on the potent bacterial mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone: aqueous stability, XAD recovery and analytical determination in drinking water and in chlorinated humic acid solutions.

Abstract: 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was detected by gas chromatography/mass spectrometry in drinking water samples from 3 locations in the U.S.A., and also in a chlorinated humic acid solution. MX appears to account for a significant proportion of the mutagenicity of these samples, as measured in the Ames test using strain TA100 without metabolic activation. Studies on recovery of MX from spiked water samples by XAD-2/8 resin adsorption/acetone elution indicated that sample acidification prior to resin adsorption was essential to the effective recovery of MX. The stability of MX in aqueous solution was pH and temperature dependent. At 23 degrees C the order of stability, based on persistence of mutagenic activity was found to be: pH 2 greater than pH 4 greater than pH 8 greater than pH 6. The half-life at pH 8 and 23 degrees C was 4.6 days. One of the degradation products has been tentatively identified as 2-chloro-3-(dichloromethyl)-4-oxo-2-butenoic acid, an open form of MX which appears to be in the "E" configuration. Overall, these results suggest that MX is formed during water chlorination as a result of reaction of chlorine with humic substances, and that a substantial fraction of the MX formed is likely to persist throughout the distribution system.

Kinetic studies of the reduction of aromatic AZO compounds in anaerobic sediment/water systems

Abstract: The reductive transformation of azobenzene and selected derivatives was investigated in anaerobic sediment/water systems. The azo compounds exhibited pseudo-first-order disappearance kinetics through at least three half-lives. The reduction kinetics of these compounds was studied as a function of their reduction potential and sediment/water distribution coefficient. There was no apparent correlation between the observed disappearance rate constant and reduction potential. In general, as the distribution coefficient increased, the rate of reduction decreased. Values for the pseudo-first-order rate constant for disappearance ranged from 5.11 × 10−3 min−1 for methyl red to 6.03 × 10−6 min−1 for 4,4′-dichloroazobenzene. Removal of the solid phase from the sediment/water samples gave a filtrate with little or no reactivity. Chemical sterilization of the sediment/water sample with formaldehyde and treatment with m-cresol, a dehydrogenase inhibitor, or sodium azide, a metabolic inhibitor, had little effect on the observed reduction rate constants for azobenzene, indicating an abiotic reduction process. Heat sterilization indicated that the reducing agent was heat labile. In studies with 4,4′-dimethoxyazobenzene, the observed rate constant for reduction increased with increasing sediment concentration. Based on the results of these studies, a model for the reduction process was developed that incorporates a nonreactive sorptive sink and a reactive site, both of which are associated with the sediment.

Encystation and expression of cyst antigens by Giardia lamblia in vitro

Abstract: The cyst form of Giardia lamblia is responsible for transmission of giardiasis, a common waterborne intestinal disease. In these studies, encystation of Giardia lamblia in vitro was demonstrated by morphologic, immunologic, and biochemical criteria. In the suckling mouse model, the jejunum was shown to be a major site of encystation of the parasite. Small intestinal factors were therefore tested as stimuli of encystation. An antiserum that reacted with cysts, but not with cultured trophozoites was raised in rabbits and used as a sensitive probe for differentiation in vitro. Cultured trophozoites that were exposed to bile salts showed a more than 20-fold increase in the number of oval, refractile cells that reacted strongly with anticyst antibodies, and in the expression of major cyst antigens. Exposure to primary bile salts resulted in higher levels of encystation than exposure to secondary bile salts. These studies will aid in understanding the differentiation of an important protozoan pathogen.

Structure-Toxicity Relationships for Industrial Chemicals Causing Type (II) Narcosis Syndrome

Abstract: Several structure-activity relationships have been published for estimating the lethality of nonpolar nonelectrolytes to fish. The vast majority of non-reactive industrial chemicals produce toxicity symptoms consistent with narcosis. However, we have found that many chemicals which appear to produce narcosis, are substantially more toxic than the published structure-toxicity relationship predicts. We observed that these chemicals are more polar and often have acidic hydrogen bond donor functional groups. The data are consistent with the “polar” narcotic class proposed by Ferguson five decades ago.

Mutagenic and clastogenic properties of 3-chloro-4-(dichloromethyl)-5-hydroxy-2 (5H)-furanone: a potent bacterial mutagen in drinking water.

Abstract: 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to be a direct-acting mutagen in the Ames test for strains TA1535, TA1538, TA92, TA97, TA98, TA100 and TA102. The highest mutagenic response (approximately 13,000 revertants/nmol) was seen in strain TA100. The TA100 response was six- to tenfold higher than in TA98, TA97, and TA102, and 100- to 500-fold higher than in TA1535, TA92, and TA1538. The addition of a 9,000 x g supernatant fraction (S-9) from livers of polychlorinated biphenyl-treated rats, along with cofactors for NADPH generation, resulted in a 90% reduction in the TA100 mutagenicity. MX induced chromosomal aberrations in Chinese hamster ovary cells after 6-8 hr exposure without S-9 at a dose as low as 4 micrograms/ml, and after 2 hr exposure with S-9 at a dose of 75 micrograms/ml. The oral dose of MX lethal to 50% (LD50) in Swiss-Webster mice was determined to be 128 mg/kg. MX did not induce micronuclei in mouse bone marrow when administered by oral gavage at doses up to 70% of the LD50.

Chemical carcinogens. A review and analysis of the literature of selected chemicals and the establishment of the Gene-Tox Carcinogen Data Base. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

Abstract: The literature on 506 selected chemicals has been evaluated for evidence that these chemicals induce tumors in experimental animals and this assessment comprises the Gene-Tox Carcinogen Data Base Three major sources of information were used to create this evaluated data base: all 185 chemicals determined by the International Agency for Research on Cancer to have Sufficient evidence of carcinogenic activity in experimental animals, 28 selected chemicals bioassayed for carcinogenic activity by the National Toxicology Program/National Cancer Institute and found to induce tumors in mice and rats, and 293 selected chemicals which had been evaluated in genetic toxicology and related bioassays as determined from previous Gene-Tox reports The literature data on the 239 chemicals were analyzed by the Gene-Tox Carcinogenesis Panel in an organized, rational and consistent manner Criteria were established to assess individual studies employing single chemicals and 4 categories of response were developed: Positive, Negative, Inconclusive (Equivocal) and Inconclusive After evaluating each of the individual studies on the 293 chemicals, the Panel placed each of the 506 chemicals in an overall classification category based on the strength of the evidence indicating the presence or absence of carcinogenic effects An 8-category decision scheme was established using a modified version of the International Agency for Research on Cancer approach This scheme included two categories of Positive (Sufficient and Limited), two categories of Negative (Sufficient and Limited), a category of Equivocal (the evidence of carcinogenicity from well-conducted and well-reported lifetime studies had uncertain significance and was neither clearly positive nor negative), and three categories of Inadequate (the evidence of carcinogenicity was insufficient to make a decision, however, the data suggested a positive or negative indication) Of the 506 chemicals in the Gene-Tox Carcinogen Data Base, 252 were evaluated as Sufficient Positive, 99 as Limited Positive, 40 as Sufficient Negative, 21 as Limited Negative, 1 as Equivocal, 13 as Inadequate with the data suggesting a positive indication, 32 as Inadequate with the data suggesting a negative indication, and 48 Inadequate with the data not suggesting any indication of activity This data base was analyzed and examined according to chemical class, using a 29 chemical class scheme(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation of Aquatic Microbial Communities to Hg2+ Stress

Abstract: The mechanism of adaptation to Hg2+ in four aquatic habitats was studied by correlating microbially mediated Hg2+ volatilization with the adaptive state of the exposed communities. Community diversity, heterotrophic activity, and Hg2+ resistance measurements indicated that adaptation of all four communities was stimulated by preexposure to Hg2+. In saline water communities, adaptation was associated with rapid volatilization after an initial lag period. This mechanism, however, did not promote adaptation in a freshwater sample, in which Hg2+ was volatilized slowly, regardless of the resistance level of the microbial community. Distribution of the mer operon among representative colonies of the communities was not related to adaptation to Hg2+. Thus, although volatilization enabled some microbial communities to sustain their functions in Hg2+-stressed environments, it was not mediated by the genes that serve as a model system in molecular studies of bacterial resistance to mercurials.

Human Variability in Susceptibility to Toxic Chemicals— A Preliminary Analysis of Pharmacokinetic Data from Normal Volunteers

Abstract: The tenfold “uncertainty” factor traditionally used to guard against human interindividual differences in susceptibility to toxicity is not based on human observations. To begin to build a basis for quantifying an important component of overall variability in susceptibility to toxicity, a data base has been constructed of individual measurements of key pharmacokinetic parameters for specific substances (mostly drugs) in groups of at least five healthy adults. 72 of the 101 data sets studied were positively skewed, indicating that the distributions are generally closer to expectations for log-normal distributions than for normal distributions. Measurements of interindividual variability in elimination half-lives, maximal blood concentrations, and AUC (area under the curve of blood concentration by time) have median values of log10 geometric standard deviations in the range of 0.11–0.145. For the median chemical, therefore, a tenfold difference in these pharmacokinetic parameters would correspond to 7–9 standard deviations in populations of normal healthy adults. For one relatively lipophilic chemical, however, interindividual variability in maximual blood concentration and AUC was 0.4—implying that a tenfold difference would correspond to only about 2.5 standard deviations for those parameters in the human population. The parameters studied to date are only components of overall susceptibility to toxic agents, and do not include contributions from variability in exposure- and response-determining parameters. The current study also implicitly excludes most human interindividual variability from age and illness. When these other sources of variability are included in an overall analysis of variability in susceptibility, it is likely that a tenfold difference will correspond to fewer standard deviations in the overall population, and correspondingly greater numbers of people at risk of toxicity.

Seasonal toxicity of ammonia to five fish and nine invertebrate species.

Abstract: Ammonia is a widely distributed chemical found in surface waters. Its toxicity to aquatic life is principally due to the un-ionized (NH3) form. An extensive review on ammonia toxicity to aquatic life has been recently compiled by the US EPA with most information consisting of fish test values and limited data available for aquatic plants and invertebrates. Invertebrates were found to be generally more tolerant to ammonia than were fishes. This laboratory study is part of a larger evaluation in assessing the impact of ammonia nitrogen in outdoor experimental streams at and above derived water quality criteria concentrations. Primary objective for this laboratory study was to determine the relative sensitivity of un-ionized ammonia to fish and invertebrates in river water at ambient seasonal temperatures.

Guide for the Salmonella typhimurium/mammalian microsome tests for bacterial mutagenicity.

Abstract: Since its development by Dr. Bruce Ames and his coworkers, the Salmonella typhimurium/mammalian microsome mutagenicity assay has been used widely throughout the world. Many authors have suggested various modifications and made recommendations in regards to this assay. Although the recommendations of a panel of experts was published in 1979 by de Serres and Shelby, a committee of members of the Environmental Mutagen Society (EMS) initiated this effort in response to the encouragement by the American Society of Testing and Materials (Committee E47.09.01) and because of new developments within the field of microbial mutagenesis testing. Its purpose is to provide a guide for people who perform or evaluate microbial mutagenesis tests, but it is not intended for these recommendations to replace or diminish the usefulness of presently available protocols and procedures.

Long-term biological data sets: Their role in research, monitoring, and management of estuarine and coastal marine systems

Abstract: Long-term records of biological data are extremely valuable for documenting ecosystem changes, for differentiating natural changes from those caused by humans, and for generating and analyzing testable hypotheses. Long-term sampling, however, is generally discouraged by a variety of institutional disincentives, so that today such records are uncommon. We discuss approaches for overcoming these disincentives through improved research planning and design, including clearera priori definition of management and regulatory actions and information needs, more rigorous adherence to hypothesis formulation and testing, and proper spatial and temporal scaling in sampling. We distinguish between prospective study design, in which the foregoing elements are essential for coast-effectiveness, and retrospective analysis, which relies on reconstruction of long-term records from existing data sets. We demonstrate the great value of retrospective analysis of encountered data, and argue for renewed attention to archival of data sets with documented data quality, interacalibration and documentation of methodologies, and long-term storage of samples for future analysis. Such practices are essential to ensure the quality of long-term records that are reconstructed for retrospective examination of new hypotheses in the future.

Sulfur retention at intensively studied sites in the U.S. and Canada

Abstract: We compiled and summarized current literature on S input/output budgets for intensively studied sites and soil plots in the U.S. and Canada and found S retention to be related to both soil order and extent of the last glaciation (Wisconsinan). Zero net retention is associated with Spodosols and was found only at sites north of the limit of Wisconsinan glaciation. Sites south of the limit of glaciation appear to be retaining from 20 to 90% of incoming S. These findings support the hypothesis that there exist regional variations in S retention in North America. Such variations are important in determining and predicting effects of acidic deposition on surface water chemistry.

Use of respiratory-cardiovascular responses of rainbow trout (Salmo gairdneri) in identifying acute toxicity syndromes in fish: Part 2. malathion, carbaryl, acrolein and benzaldehyde

Abstract: An in vivo fish model was used to monitor the respiratory-cardiovascular responses of individual spinally transected rainbow trout exposed to acutely toxic aqueous concentrations of two acetylcholinesterase (AChE) inhibitors, malathion and carbaryl, and two mucous membrane irritants, acrolein and benzaldehyde. The most striking changes in respiratory-cardiovascular physiology noted on malathion and carbaryl exposures were immediate decreases in oxygen utilization (U) and heart rate (HR). Ventilation volume (VG) increased to compensate for the lower U, but not enough to increase oxygen consumption (VO2). Blood responses in carbaryl-exposed trout differed from those in the malathion group; there were increased hematocrit (Hct) and hemoglobin (Hb) values along with an extensive drop in arterial pH (pHa) and total arterial carbon dioxide (TaCO2). The overall respiratory-cardiovascular responses of the rainbow trout to acrolein and benzaldehyde intoxication represent a direct effect of the chemical at the respiratory surface. A steady increase in cough rate (CR) was recorded for fish exposed to both chemicals throughout exposures. A moderate to low increase in VG and VO2 was followed at 50 to 60% survival time by sudden decreases in VG and VO2 until death. Ventilation rate (VR), U and HR showed a steady downward trend over the entire survival period. After the midpoint in survival time, total arterial oxygen (TaO2), (TaCO2) and pHa all decreased, while Hct increased steadily. Individual principal components analyses of the cardiovascular-respiratory responses of fish exposed to the four chemicals showed that the variables were highly correlated and that the first two principal components explained 55 to 70% of the variation in the 18 parameters analyzed. A two-dimensional diagram of the first two principal components illustrated this multivariate response and the increased variability in the responses of exposed fish as compared with the control fish. Sets of toxic responses were developed to describe two new fish acute toxicity syndromes (FATS), one for AChE inhibitors and one for respiratory irritants. These were combined with the FATS for respiratory uncouplers and narcotics from previous work prior to discriminant function analysis (DFA). DFA was used to predict the specific FATS for a chemical based on the cardiovascular-respiratory responses observed during intoxication. DFA on these responses resulted in a 100% correct separation of four specific FATS for all 32 trout tested. Of the 18 responses monitored and used in the DFA, CR, VO2, TaO2, pHa and U were the best discriminators in predicting the correct FATS for each fish.

Use of respiratory‐cardiovascular responses of rainbow trout (Salmo gairdneri) in identifying acute toxicity syndromes in fish: Part 1. pentachlorophenol, 2,4‐dinitrophenol, tricaine methanesulfonate and 1‐octanol

Abstract: An in vivo fish model was adapted to monitor respiratory-cardiovascular responses of spinally transected rainbow trout exposed to acutely toxic aqueous concentrations of two uncouplers of oxidative phosphorylation, pentachlorophenol (PCP) and 2,4-dinitrophenol (DNP), and two narcotics, tricaine methanesulfonate (MS-222) and 1-octanol. The most evident toxic response to the uncouplers was a rapid 150 to 200% increase in ventilation volume (VG) and oxygen consumption (VO2) over the entire survival period. This caused an initial increase in total arterial oxygen (TaO2) content of the blood, which then fell slowly as the tissues used more and more oxygen to generate ATP. Arterial blood pressure (BPa) and other blood measurements did not change appreciably in response to PCP, yet DNP caused increases in hematocrit (Hct) and hemoglobin (Hb) and slight decreases in total arterial carbon dioxide (TaCO2) and arterial pH (pHa). In contrast to the uncouplers, the response of the respiratory-cardiovascular system of trout to toxic levels of narcotics was a dramatic slowing of all respiratory-cardiovascular functions. While VG and VO2 decreased 40 to 50% from predose levels, oxygen utilization (U) increased 20 to 30%. Ventilation rate (VR) declined initially and then increased slowly until death occurred, but remained within the control range. As respiration declined TaCO2 significantly decreased, as did pHa. In response to hypoxia, Hct increased substantially, and Hb increased slightly only in the 1-octanol exposure. A rapid 40 to 50% drop in heart rate (reflex bradycardia) was also observed. The final phase of toxicity caused by both uncouplers and narcotics appeared to eventually produce acute tissue hypoxia, with a generalized loss of respiratory-cardiovascular coordination, and finally respiratory paralysis. Individual principal component analyses of the cardiovascular-respiratory responses of fish exposed to the first two principal components explained 68 to 76% of the variation in the 18 parameters analyzed. A two-dimensional diagram of the first two principal components illustrated this multivariate response and the increased variability in the responses of exposed fish as compared with control fish. The general sets of responses described for these two fish acute toxicity syndromes have provided the initial information necessary to group similar responses caused by other chemicals into a fish uncoupler syndrome, a fish narcosis syndrome or some new syndrome.