Maximum Acceptable Concentration Research Articles

Short-term effects of mercury on survival, behaviour, bioaccumulation and ionic pattern in the catfish ( Clarias Lazera)

1. The fresh-water fish, Clarias lazera, was exposed to 13 lethal and sublethal concentrations of mercury. 2. The median tolerance limit (TLm) at different exposure periods, 24, 48, 72 and 96 hr, appears to be as follows: 0.96, 0.88, 0.81 and 0.72 ppm Hg 2+/l, respectively. 3. From the subacute tests, the maximum acceptable toxicant concentration (MATC) for this fish was between 0.10 and 0.22 ppm Hg 2+/l. 4. Behavioural changes, tissue Hg 2+ distribution and serum ionic patterns were recorded during both the acute and subacute exposure periods.

ESTIMATING RESPONSES OF FISH POPULATIONS TO TOXIC CONTAMINANTS

In assessments of risks of toxic contaminants to fish populations, the endpoints of ultimate interest are the persistence, abundance, and production of populations. In this article we demonstrate a method for expressing toxicity test data obtained from full-life-cycle tests in terms of the same indices used to assess effects of harvesting and power-plant cooling systems on fish populations. Our approach involves fitting the logistic concentration-response function to chronic test data and coupling the functions obtained to a fish life-cycle model. Confidence bands derived from the data quantify uncertainties inherent in predicting population-level effects from (1) full-life-cycle test data for the species of interest, (2) extrapolation of a concentration-response function from an acute LC50 for the species of interest, and (3) extrapolation from an acute LC50 for another species. Using rainbow trout and largemouth bass as representative species, we evaluate the relative importances of three sources of uncertainty contributing to prediction intervals for populationlevel effects. We also compare population-level concentration-response functions to predicted and experimentally derived maximum acceptable toxicant concentrations for five toxic chemicals.

The application of regional geochemical reconnaissance data for uranium in surface waters to identifying environmentally sensitive areas

Examination of National Geochemical Reconnaissance (NGR) maps produced by the Geological Survey of Canada showing trace-element concentrations in stream water and sediment from southern British Columbia, reveals several areas where U levels in water are significantly elevated. Some of the values reported, including those for stream waters used to supply domestic needs, approach the 20 ppb maximum acceptable concentration for drinking water. In order to evaluate the application of NGR data, collected originally for use in mineral exploration, to identifying areas of possible public health concern, a follow-up sampling program was undertaken. Both surface and, where possible, groundwater samples were obtained at 12 sites representing a range (<1–20 ppb) of expected U concentrations. Samples were collected at approximately monthly intervals over a period of from 12 to 26 months. The parameters measured included total U, conductivity and pH. Uranium concentrations were found to vary considerably, both on a seasonal and annual basis, in response to changes in stream discharge. Means calculated over the period of this study were, nevertheless, very similar to NGR values, which are based on the analysis of only individual grab samples. Because, however, most NGR sampling was carried out in June and July, when stream discharge is at an intermediate stage, NGR data sometimes seriously underestimated maximum concentrations typically associated with periods of minimum discharge in late autumn and winter. Comparison of U concentrations in tap water and those in source streams indicates that water treatment procedures in these areas normally have little effect on U levels. Thus NGR map data probably represent, more or less accurately, typical U values in drinking water obtained from streams. Although only a few groundwater samples were obtained, results suggest that NGR data can, however, considerably underestimate the U content of tap water obtained from wells. It is concluded that NGR maps for U in streams in southern British Columbia can be used to locate areas where U intake via drinking water may be excessive. In this study, follow-up sampling in anomalous areas identified several sources of domestic water wherein U concentrations periodically exceed the 20-ppb maximum acceptable level. These results suggest more generally that the NGR data base, when properly interpreted, is a valuable but still largely untapped source of information of environmental and public health concern.

Toxicity of four pesticides on the fingerlings of Indian major carps Labeo rohita, Catla catla, and Cirrhinus mrigala

Fingerlings of Labeo rohita, Catla catla, and Cirrhinus mrigala were exposed to selected doses of four commonly used pesticides carbofuran, DDT, dimethoate, and Meta-Systox for a period up to 30 days to determine relative toxicological effects, LC 50 values for 96 hr, maximum acceptable tolerant concentration, and application factor. The use of early life history tests has been emphasized for toxicological assessments.

Acute and chronic effects of water quality criteria‐based metal mixtures on three aquatic species

AbstractAcute and chronic toxicity tests were conducted with three aquatic species to determine the effects of metals combined as mixtures at proposed water quality criteria concentrations and at multiples of the LC50 and maximum acceptable toxicant concentration (MATC) obtained from tests on six metals. These studies were the first part of a larger research effort to derive water quality criteria for combined pollutants by the U.S. Environmental Protection Agency.Arsenic, cadmium, chromium, copper, mercury and lead combined at criterion maximum concentrations caused nearly 100% mortality in rainbow trout and daphnids (Ceriodaphnia dubia) during acute exposures. Fathead minnows were not adversely affected at this or two times this concentration, although a mixture of four to eight times the maximum value caused 15 to 60% mortality. Metals combined at the criterion average concentrations significantly reduced production of daphnid young and growth of fathead minnows after 7 and 32 d, respectively. Embryo hatchability and survival of rainbow trout were reduced at four times this criterion but not at the criterion average concentration.Acute tests with metals mixed at multiples of the LC50 indicated that the joint action of the metals was more than additive for fathead minnows and nearly strictly additive for daphnids, based on toxic units calculated from the individual components of the mixture. Chronic tests showed that the joint action was less than additive for fathead minnows but nearly strictly additive for daphnids, indicating that long‐term metal interactions may be different in fish than in lower invertebrates. Adverse effects were observed at mixture concentrations of one‐half to one‐third the MATC for fathead minnows and daphnids, respectively, suggesting that components of mixtures at or below no effect concentrations may contribute significantly to the toxicity of a mixture on a chronic basis. These results point out the need for additional studies to determine the type and degree of interaction of toxicants because single‐chemical water quality criteria may not sufficiently protect some species when other toxicants are also present.

Acute and chronic toxicity of ammonia to freshwater fish: A site‐specific study

The toxicity of ammonia to the juvenile stages of the bluegill (Lepomis macrochirus) and the walleye (Stizostedion vitreum), and to the embryo, larval and juvenile stages of the fathead minnow (Pimephales promelas) was determined in support of the development of a site-specific water quality standard for ammonia in the Tittabawassee River at Midland, Michigan. There was little difference among the acute toxicities of ammonia (expressed as un-ionized ammonia nitrogen NH3 -N) to the three species tested, with 96-h LC50 values of 1.04, 1.06 and 1.50 mg NH3 -N/L for the bluegill, walleye and fathead minnow, respectively. Evaluation of the chronic data showed no concentration-related effects for hatching success and growth. However, there was a significant (α = 0.05) decrease in number of normal larvae at hatch and in larval survival at 0.26 mg NH3 -N/L and higher. The maximum acceptable toxicant concentration fell between 0.17 and 0.26 mg NH3 -N/L, or 0.21 mg NH3 -N/L when expressed as the geometric mean of these values. Both the acute and chronic values derived during this study are similar to those reported in the literature, indicating that, in this case, Tittabawassee River water quality did not influence the toxicity of ammonia to the species tested.

Site‐specific acute and chronic toxicity of ammonia to Daphnia magna straus

The acute and chronic toxicity of ammonia (expressed as un-ionized ammonia nitrogen, NH3 -N) to Daphnia magna was determined in support of the development of site-specific water quality standards for ammonia in the Tittabawassee River at Midland, Michigan. The 48-h LC50 value (95% confidence interval) obtained was 2.94 (2.70 to 3.22) mg NH3 -N/L. The 21-d chronic value, presented as the maximum acceptable toxicant concentration (MATC), was between 0.42 and 0.87 mg NH3 -N/L. Expressing the chronic value as the geometric mean of 0.42 and 0.87 resulted in an MATC of 0.60 mg NH3 -N/L. The toxicity values derived during this study were similar to those reported in the literature for D. magna.

Acute and chronic toxicity of nickel to larvae of chironomus riparis (Meigen)

The acute toxicity of nickel to first and second instars of Chironomus riparis was determined using larvae from a laboratory culture. First instar larvae were found to be significantly more sensitive to nickel than second instars with 48h LC 50 values of 79·5 ± 3·7 mg litre −1 Ni and 169 ± 10 mg litre −1, respectively. Longer term chronic toxicity tests (30 days), in which larvae were allowed to develop from eggs until just prior to pupation, indicated that nickel concentrations of up to 25 mg litre −1 appeared to have little effect on the percentage hatch of C. riparis. The growth of larvae was, however, significantly reduced at the lowest nickel concentration (2·5 mg litre −1) tested compared with control larvae. A maximum acceptable toxic concentration (MATC) for the effect of nickel on growth was estimated to be 1·1 mg litre −1 Ni. This value is substantially lower than the LC 50 value calculated for first instar larvae and indicates the importance of conducting longer term toxicity tests when assessing the pollution tolerance of an organism.

Development of an instrument for the dynamic generation of test gases

A test generator for the dynamic generation of test gases was developed. This device utilizes the saturation vapour pressure principle and enables the calibration of sensitive analytical methods (e. g. gas chromatography) with substance concentrations in the range of maximum acceptable concentrations (MAK- resp. TRK-values). The test gases are producible from liquid and solid substances with finite vapour pressure. The test gas concentration can be calculated from instrumental conditions and the vapour pressure of the substance at a known temperature. Beside the possibility of the continuous and automatic calibration of the measuring monitors the test gas generator is a successful instrument to study interference and adsorption processes. The produced gas stream volumina are infinitely variable to be adjusted to the sampling volumina of different sampling systems (e.g. personal pumps for personal-air-sampling). Component concentrations are determined with a standard deviation of less than 2.3%. In recent research programs the test gas generation from benzene, toluene, xylene, methanol, methanal and phenol has been demonstrated.

Contamination of firn layers by radioactive fission products from atmospheric fallout.

Measurements of gross beta activity and 3H concentration of firn samples from different regions can be used to determine environmental contamination by radioactive fallout from nuclear weapons tests in the atmosphere since 1952. The exposure dose to the population due to radioactive fission products in the drinking water supply from glacierized areas is compared to maximum acceptable concentrations derived from ICRP annual limits of intake (ALI). It is shown that even from heavily contaminated layers the risk to the population is acceptable.

Fate and effects of 3,4‐dichloroaniline in the laboratory and in outdoor ponds: II. chronic toxicity to Daphnia SPP. and other invertebrates

AbstractThe effects of 3,4,‐dichloroaniline (DCA) on survival, growth and reproduction of the planktonic crustacean Daphnia magna were evaluated in the laboratory using a procedure based on Organization for Economic Cooperation and Development guidelines. Effects on reproduction, the most sensitive of the measured biological responses, occurred at a concentration of 20 μg/L but not at 10 μg/L or at lower concentrations. These, and similar results reported elsewhere, were used to calculate the maximum acceptable toxicant concentration (MATC) for D. magna.In acute toxicity tests with D. magna and D. longispina the 48‐h EC50 values were 290 and 440 μg/L, respectively. An estimate of the MATC for D. longispina was then obtained by multiplication of the MATC for D. magna by the ratio of the 48‐h EC50 values for the two species.A field experiment was carried out to compare the chronic toxicity of DCA in the laboratory with effects on populations of zooplankton and communities of macroinvertebrates in outdoor ponds. Three ponds were treated with DCA at a nominal concentration of 45 μg/L and three at 450 μg/L. These concentrations were maintained in the water for 28 d. Three untreated ponds were used as controls. Population densities of the dominant species of zooplankton were monitored before, during and after treatment with DCA. Samples of the macroinvertebrate communities were taken immediately after the end of treatment. Birth, death and growth rates of D. longispina populations were monitored using Perspex cylinders to confine samples of adults in situ for periods of 24 h.Population densities of D. longispina were significantly affected (p ≤ 0.05) by both treatment levels. There were no adverse effects on the population densities of two species of copepods and no changes were observed in the structure of macroinvertebrate communities. It was concluded that the Cladocera were much more susceptible to DCA than were other groups of invertebrates in the outdoor ponds.Birth and growth rates of D. longispina populations were highly sensitive to the effects of DCA. They were depressed when concentrations of DCA were maintained at a level greater than the MATC and increased rapidly when concentrations decreased below this level. Thus, the MATC, derived from the results of toxicity tests, provided an accurate estimate of threshold concentrations affecting field populations of D. longispina.

Fish subchronic toxicity prediction model for industrial organic chemicals that produce narcosis

AbstractA model based on partition coefficient was developed for predicting subchronic toxicities of selected chemicals to fish. Early life stage tests were conducted under flow‐through conditions using fathead minnows (Pimephales promelas) as test organisms. Embryos, larvae and juveniles were continuously exposed to chemicals for a total of 31 to 33 d. Test endpoints included egg hatchability, incidence of developmental abnormalities, survival and growth. The “chronic value” for each test was a point estimate of the maximum acceptable toxicant concentration (MATC), and was determined as the geometric mean of the highest test concentration producing no effect and the lowest concentration significantly (p ≤ 0.05) affecting one or more endpoints. Ten industrial organic compounds from four chemical classes (ketones, benzenes, ethers and alkyl halides) were used in model development. All chemicals were considered to induce narcosis in fish in acute toxicity tests. The relationship between estimated MATC n‐octanol/water partition coefficient (log P) was expressed by the equationlog estimated MATC (mol L−1) = ‐0.886 log P ‐ 2.18 (r2 = 0.925).This model was used to predict subchronic toxicities for eight other alkyl halides and chlorinated benzenes that had been tested with fathead minnows and reported in the literature. The mean ratio for observed chronic toxicity value to predicted chronic toxicity value was 2.00 ± 2.03. Observed values ranged from 0.29 to 6.02 times the predicted values. For the 10 chemicals used in the model, the mean acute/chronic toxicity ratio (96‐h LC50/chronic value) was 12.2 ± 8.5.

Acute and Chronic Toxicity of Atrazine to Estuarine Fauna

Acute and chronic estuarine invertebrate and fish toxicity testes were conducted to evaluate possible consequences of measured concentrations of atrazine in estuarine areas. The 96-h LC50 values ranged from 0.094 mg per 1 for copepods to >30 mg per 1 for larvae of eastern oysters. Maximum acceptable toxicant concentrations of >0.08 1.9<3.4 mg per 1 were determined for mysid shrimp and sheepshead minnows, respectively in life cycle and early life cycle testes. The approximate application factor limits in both tests were 0.1–0.2. Use of an application factor of 0.1 with the most sensitive species tested acutely provides a no effect, concentration of approximately 0.009 mg per 1 for estuarine fauna. Therefore, the maximum reported measured concentration of approximately 0.002 mg per 1 atrazine in estuarine areas would not be suspected to adversely impact estuarine fauna.

Effect of selenite and seleniferous fly-ash leachate on growth and viability of the marine amphipod Allorchestes compressa

Juveniles of the amphipod Allorchestes compressa Dana were exposed to sodium selenite and to seleniferous leachate from coal fly-ash. A maximum acceptable toxicant concentration (MATC) for selenite of >44<93 μg Se l-1 is indicated by the results for growth and viability. Leachate:sea water mixtures produced effects which were consistent with selenite toxicity but quantitatively less drastic than expected from the pure selenite work, perhaps because of sulphate antagonism. The results are compared with selenium toxicity data for other aquatic species, and high-light the difficulties of using application factors as the basis for water-quality criteria.

Methods for conducting snail (Aplexa hypnorum) embryo through adult exposures: Effects of cadmium and reduced pH levels

Two separate embryo through adult exposures were conducted with cadmium and with reduced pH levels to validate various test methodologies and to determine the feasibility of testing and ease of handling the freshwater snail (Aplexa hypnorum) in a test system designed for fish bioassays. Exposure of snails from embryos through adult reproductive maturity to cadmium chloride produced delayed hatch, reductions in percentage hatch and survival, and reduced growth when compared to a control. Based on these effects, the maximum acceptable toxicant concentration in Lake Superior water was between 4.41 and 7.63 μg cadmium/L in one test and between 2.50 and 4.79 μg cadmium/L in another test. Adult snails were exposed to determine a 96-hr LC50 of 93 μg cadmium/L. Exposure of embryonic, larval and adult snails to a pH range of 5.00–5.75 caused delayed hatching, reduced combined hatchability and survival, reduced 26-day growth, and a reduction in the number of egg masses per adult snail. No adverse effects were observed in snails exposed for 26 days to pH values ranging from 6.25 to 6.65. During a short-term static exposure, a pH of 4.3 caused a cloudy appearance in eggs within the egg mass and killed the embryos within two hr of the start of the exposure. A static pH exposure of 4.6 also turned embryos slightly cloudy, although some development did occur in these embryos by the sixth day.

Four years experience with a mercury shielded irregular field system (MSIFS).

A mercury shielded irregular field system (MSIFS) has been in use in our department since January 1979. The system is described and illustrated. Experience in treating 225 patients demonstrated that the system is accurate and reproducible. The system offers a choice of shielding efficiency in a transmission range from 100 to 3.5% for 18 MV photons. Routine measurements of mercury vapor concentration in the treatment room showed values below 0.02 mg Hg/m3 air. (The maximum acceptable concentration in The Netherlands is 0.05 mg Hg/m3 air.) It is concluded that the system is cost-effective, easy to use, and flexible and safe.

The influence of speciation on the toxicity of silver to fathead minnow (Pimephales promelas)

AbstractSilver sulfide, silver thiosulfate complex and silver chloride complexes were tested and compared with free silver ion for their toxic effects in 96 h flow through acute toxicity tests using fathead minnows (Pimephales promelas). Thirty day fathead minnow embryo larval tests were conducted with silver sulfide and silver thiosulfate complex. Extensive chemical analyses were performed to quantify actual exposures. Compared with free silver ion, silver chloride complexes were about 300 times less toxic acutely silver sulfide was at least 15,000 times less toxic acutely and silver thiosulfate complex was more than 17,500 times less toxic acutely. The estimated maximum acceptable toxicant concentrations (MATCs) determined from the embryo larval tests with silver sulfide and silver thiosulfate complex were greater than 11 mg/L (as total silver) and greater than 16 but less than 35 mg/L (as total silver), respectively. The MATC previously reported for free silver ion from tests with rainbow trout (Salmo gairdneri) was greater than 0 00009 but less than 0 00017 mg/L. These differences in acute toxicities and the differences of five orders of magnitude in the MATC values are attributed to the influence of chemical speciation on the effects of silver in the aquatic environment. Thus, the speciation of silver is an essential factor in its potential to affect fish and, presumably, other aquatic life, and therefore should be considered in environmental risk assessment.

Evaluation of a static renewal chronic toxicity test method for Daphnia magna straus using boric acid

AbstractA procedure for conducting chronic daphnid static renewal tests has been developed and evaluated, using boric acid as the test material. This procedure is an improvement over other proposed procedures for the following reasons: (a) the test methodology and equipment simplify the operations required to perform the test, (b) data on all endpoints for a particular concentration are obtained from the same group of test organisms and (c) the experimental design permits statistical interpretation of the critical endpoints. The acute and chronic effects of boric acid on Daphnia magna were similar to those reported in the literature. The 48‐h static acute LC50 value (and 95% confidence intervals) for boric acid were 133 (115–153) mg/L as boron. The chronic toxicity of boric acid estimated by derivation of the maximum acceptable toxicant concentration was between 6.4 and 13.6 mg/L as boron.

Toxicity of selected priority pollutants to various aquatic organisms

Toxicity tests were conducted with selected compounds listed by the United States Environmental Protection Agency (EPA) as priority pollutants. Acute toxicity information was determined for acenaphthene, arsenic trioxide, cadmium chloride, mercury(II) chloride, silver nitrate, chlordane, endosulfan, and heptachlor. Acute tests were conducted using one or more of the following species: fathead minnows ( Pimephales promelas), channel catfish ( Ictalurus punctatus), rainbow trout ( Salmo gairdneri), brown trout ( Salmo trutta), brook trout ( Salvelinus fontinalis), bluegills ( Lepomis macrochirus), snails ( Aplexa hypnorum), or chironomids ( Tanytarsus dissimilis). Acute values from these tests ranged from a silver nitrate 96-hr LC 50 of 6.7 μg/liter for fathead minnows to an arsenic trioxide 48-hr LC 50 of 97,000 μg/liter for chironomids. In addition to acute tests, a fathead minnow embryo-larval exposure was conducted with silver nitrate to estimate chronic toxicity. The estimated maximum acceptable toxicant concentration for silver nitrate, based on fathead minnow survival, lies between 0.37 and 0.65 μg/liter.

Lake Water Acidity and the Quality of Pumped Cottage Water in Selected Areas of Northern Ontario

Abstract Studies of the effects of standing time on the leaching of metals from the plumbing systems of cottages on three acid-rain sensitive lakes (Dickie Lake, Lake of Bays and Heeney Lake) have been carried out from August to September 1981. Passage of the lake waters through the plumbing system results in increases in pH, alkalinity and the concentrations of the metals measured: Cd, Cu, Pb and Zn. The maximum rate of leaching of metals occurred in the first 2 hours of contact time, although levels continue to rise up to 10 days. The range of leaching rates observed in (μg/l/hour) was (35–840), (14–21) and (7–254) for Cu, Pb and Zn respectively. The concentrations of Pb and Cu were closely related to the contact time and rose to or exceeded the maximum acceptable concentration “as recommended in the 1978 Canadian Drinking Water Guidelines” in the first liter of water drawn from the tap after 2 to 12 hours contact time. The maximum levels were observed in 10 day static samples where levels of 4,560 μg/l...