Lead,cadmium, and aluminum accumulation in the red swamp crayfishProcambarus clarkii G. collected from roadside drainage ditches in louisiana

The concentration of Pb, Cd, and Al in tissues of crayfishProcambarus clarkii were evaluated from several wetland sites located adjacent to roadways and were compared to crayfish harvested from a commercial site free from roadside influences. Abdominal muscle, hepatopancreas, alimentary tract, exoskeleton and blood were analyzed for metal content. Results indicated that levels of contamination obtained in almost all tissues of crayfish from roadside ditches contained significantly higher amounts of metals than those of the commercially harvested control crayfish (p = .05–.001). Detection limits of Pb, Cd, and Al ranged from 0.04 g Pb/g to 16.15 g Pb/g.001 g Cd/g to .13 g Cd/g, and 1.22 g Al/g to 981 g Al/g, respectively. Concentrations of Pb, Cd, and Al were highest in the hepatopancreas and alimentary tract. High levels of these elements were also detected in the exoskeleton. In contrast, muscle tissue was the least affected tissue. Several significant correlations among concentrations of metals were found when comparing a variety of tissues inProcambarus clarkii.     

Sublethal Effects of Trace Metals (Cd,Cr, Cu,Hg) on Embryogenesis and Larval Settlement of the Ascidian <Emphasis Type="Italic">Ciona intestinalis</Emphasis>

Toxicity of Cadmium (Cd), Chromium (Cr), Copper (Cu), and Mercury (Hg) on the early developmental stages of Ciona intestinalis was investigated. Developmental defects of larvae after exposure of gametes throughout their development to the larval stage were assessed. Gamete exposure to increasing metal concentrations resulted in a significant decrease of the percentage of normally hatched larvae, showing median effective concentrations (EC₅₀) of 721 g/L (6.42 M) for Cd, 12772 g/L (226 M) for Cr, 36.6 g/L (0.576 M) for Cu, and 44.7 g/L (0.223 M) for Hg. Larval attachment was significantly affected when gametes were exposed to the metals throughout development. The EC₅₀ reducing larval attachment by 50% were 752 g/L (6.7 M) for Cd, 15026 g/L (289 M) for Cr, 67.8 g/L (1.607 M) for Cu, and 78.1 g/L (0.389 M) for Hg. Therefore, on a molar basis Hg is three times more toxic than Cu, 20–30 times more than Cd, and 700–1000 times more toxic than Cr, for both responses.     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination on mink. II: Reproduction and kit development

Adult ranch-bred mink (Mustela vison) were fed diets containing either 0, 1.0 g/g polychlorinated biphenyls (PCB) (Aroclor^® 1254), 1.0 g/g methylmercury (MeHg), a combination of 1.0 g/g PCB plus 1.0 g/g MeHg, or 0.5 g/g PCB plus 0.5 g/g MeHg. Fertility of adult male mink, percentage of females whelped or number of kits born per female were not affected by the treatments. However, growth rate of kits nursed by mothers exposed to 1.0 g/g PCB was significantly reduced. There was a synergistic effect of PCB and MeHg which reduced kit survival in groups receiving both chemicals simultaneously. Kit survival to weaning in the control, 0.5 g/g PCB/MeHg, and 1.0 g/g PCB/MeHg groups was 72.0%, 62.7% and 35.8%, respectively. The results suggest that growth and survival of mink kits are adversely affected at dietary levels of PCB and MeHg currently present in some environments.     

Toxicity of mercury,copper, nickel,lead, and cobalt to embryos and larvae of zebrafish,Brachydanio rerio

The toxicity of mercury (HgCl₂), copper (CuCl₂: 5 H₂O), nickel (NiSO₄: 6 H₂O), lead (Pb(CH₃COO)₂: 3 H₂O) and cobalt (CoCl₂: 6 H₂O) was studied under standardized conditions in embryos and larvae of the zebrafish,Brachydanio rerio. Exposures were started at the blastula stage (2–4 h after spawning) and the effects on hatching and survival were monitored daily for 16 days. Copper and nickel were more specific inhibitors of hatching than cobalt, lead, and mercury. Nominal no effect concentrations determined from the dose-response relationships (ZEPs, Zero Equivalent Points) for effect on hatching time were 0.05 g Cu/L, 10 g Hg/L, 20 g Pb/L, 40 g Ni/L and 3,840 g Co/L, and those for effect on survival time were 0.25 g Cu/L, 1.2 g Hg/L, 30 g Pb/L, 80 g Ni/L, and 60 g Co/L. The no effect concentrations for Ni, Hg and Pb are consistent with previously reported MATC values for sensitive species of fish. The no effect concentrations for copper are 1–2 orders of magnitude lower than previously reported values. The major reason for the latter discrepancy was considered to be the absence of organics that can complex copper ions in the reconstituted water that we used, which had a hardness of 100 mg/L (as CaCO₃) and a pH of 7.5–7.7. Unexposed controls were started with embryos from different parental zebrafishes and the parental-caused variability in early embryo mortality, median hatching time and median survival time were estimated.     

Effects of different dietary levels of cadmium,lead, copper,and zinc on the vitality of the forest pest insect Lymantria dispar L. (Lymantriidae,Lepid)

Lymantria dispar (gypsy moth) larvae were reared on both a natural diet of oak leaves and an artificial medium contaminated independently with four different metal nitrates. Larvae were contaminated up to pupation either from 1st or 4th instars at four concentrations differing by a factor of 5. The lowest concentration levels were 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn based on nutrient medium dry weight. Developmental rate, growth, mortality and reproductive success were determined. No-Observed-Effect-Concentrations (NOECs) calculated were dependent on the metal, the parameter investigated and the stage at which exposure commenced. In general, larvae exposed from the 4th instar were less susceptible to metal toxification than those exposed from hatching. Considering all parameters investigated, dietary NOECs were determined to be 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn.     

Chronic toxicity of the bromoxynil formulation Buctril® to Daphnia magna exposed continuously and intermittently

Two chronic toxicity tests were conducted in which Daphnia magna were either continuously or intermittently exposed to bromoxynil octanoate (BO; as Buctril^®) for 28 d. In the intermittent exposure test, daphnids were exposed to daily pulses of BO with 24-h mean concentrations equal to those in the continuous exposure test, and the peak concentrations were three times the 24-h mean values. After 28 d of continuous exposure to BO, survival of daphnids was reduced at 80 g/L, whereas mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults were all reduced at 40 g/L. Intermittent exposures to daily pulses of BO for 28 d caused reduced survival of daphnids at 24-h mean concentrations 40 g/L and reduced mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults at 24-h mean concentrations 20 g/L. The estimated geometric mean-maximum acceptable toxicant concentrations of BO based on 24-h mean nominal values were 28 g/L for continuous exposures and 14 g/L for intermittent exposures. These results demonstrated that continuous-exposure studies may not be adequate in assessing herbicide toxicity to aquatic biota when concentrations fluctuate temporally.     

Influence of cadmium pre-exposure on the preference-avoidance responses of lake whitefish (Coregonus clupeaformis) to cadmium

The preference-avoidance responses of lake whitefish (Coregonus clupeaformis) to Cd were measured following 3 weeks exposure to water containing 0, 0.2, 1, or 5 g Cd/L. Fish movements were tracked in a countercurrent-type trough with clean water on one side, and water containing sequentially increasing Cd concentrations (0–25 g/L) on the other. While fish not previously exposed to Cd showed a weak attraction to the highest test concentration only, those pre-exposed to 5 and 1 g/L Cd were subsequently attracted to water containing Cd at the same concentration to which they had been previously exposed. This response was most pronounced among fish pre-exposed to 5 g/L, which displayed a relatively strong attraction to water containing 5 g/L when compared to responses to other test concentrations. This suggests that Cd imparts an odor or flavor which previously exposed whitefish will seek out. The possible implications of such attraction responses in field situations are discussed.     

The influence of contaminant and water quality conditions on larval striped bass in the Potomac River and upper Chesapeake Bay in 1990: Anin situ study

In situ contaminant and water quality studies were conducted with striped bass prolarvae,Morone saxatilis, in two major spawning areas of the Chesapeake Bay in 1990 to explore the possible effects of water quality and contaminants conditions on survival. Three 96-hin situ survival studies with striped bass prolarvae were conducted at three stations in the Potomac River and three stations in the upper Chesapeake Bay during a major portion of the spawning season (13–20°C). Water quality parameters, inorganic contaminants and organic contaminants were monitored in the water column at these three stations during the experiments. Concentrations of 10 metals associated with precipitation events occurring at field sites on the Potomac River and upper Chesapeake Bay were also determined.Survival of prolarvae ranged from 2 to 17.5% in all three 96-h tests conducted in the Potomac River. Control survival was greater than 79%. Survival of prolarvae during experiment 3 (all stations combined for each experiment) was significantly lower than survival of prolarvae during experiment 1. The low survival of prolarvae during experiment 3 occurred concurrently with a reported fish kill on the Potomac River. Chromium (14 g/L) and zinc (119 g/L) concentrations exceeding U.S. EPA water quality criteria were reported from a 48-h composite sample taken during experiment 3. Lower than normal pH conditions (6.8 and 6.9) were also documented during this experiment. Arsenic, chromium, and zinc may have been stressful.Survival of prolarvae at the three stations during upper Chesapeake Bay tests ranged from 36 to 52.5% for 96-h exposures but was slightly lower (23–34.5%) during a 120-h exposure. Control survival was >81% in all experiments. Survival of prolarvae during all experiments in the upper Bay was similar to natural survival that occurs with this life stage. Adverse water quality and contaminant conditions were not reported in the upper Chesapeake Bay striped bass spawning area.Detectable concentrations of cadmium (0.80 and 0.89 g/L), aluminum (5.4 g/L), chromium (1.1 g/L), and zinc (2.5 g/L) were reported in acidic precipitation samples (pH 3.4) collected from the Potomac River site. Surface water concentrations of these metals did not increase in the Potomac River study area after the precipitation events. The following metals were detected in acidic precipitation (pH 4.06–5.12) in the upper Chesapeake Bay: 22.1 g/L Al; 1.1, 1.8, 2.3 g/L Cd; 1.2 g/L Cu; 2.7 and 3.1 g/L Pb and 4.6 g/L Zn. Concentrations of Al (22.1 g/L) and Pb (3.1 g/L) in precipitation corresponded with increased concentrations in the surface waters at a nearby station in the upper Chesapeake Bay study area.     

Aquatic hazard assessment of the organophosphate insecticide fonofos

This study determined the acute and chronic toxicity of the organophosphate insecticide fonofos to standard freshwater aquatic organisms under laboratory conditions. Fonofos was acutely toxic to bluegill (Lepomis macrochirus), Daphnia (D. magna), and midge (Chironomous riparius) at 5.3, 2.7, and 39 g/L, respectively. Three fonofos formulations (technical, 94.8% A.I.; 20G, field granular 20% A.I.; and 4E, field liquid 4#/gal A.I.) exhibited similar acute toxicities to bluegill. Exposure to fonofos delayed reproduction and decreased the intrinsic rate of increase of Daphnia during 21-d chronic exposure at the lowest tested concentration (0.08 g/L). The no observable effect concentration (NOEC) for Daphnia survival was 0.42 g/L; 0% survival occurred at the lowest observable effect concentration (LOEC) of 1.45 g/L. The NOEC for midge emergence was 3.42 g/L; only 34% emergence occurred at the LOEC of 8.24 g/L. Chronic 30-d exposure of juvenile bluegills decreased growth and survival at 5.65 g/L (LOEC), but no effects occurred at 2.33 g/L (NOEC). The relative hazard of fonofos to aquatic life is similar to other carbamate and organophosphate corn insecticides.     

The disposition of cadmium and zinc inPandalus montagui

Cadmium uptake rates in various tissues ofPandalus montagui exposed to sea water containing 37 gCd/L for 14 days ranged from 0.002–0.06 g/g dry tissue/hr. During depuration for 57 days, the levels in most tissues decreased slightly, but continued to rise in the hepatopancreas indicating Cd redistribution. Exposure to 65 g Zn/L produced no substantial change in Zn content of the tissues. An increase occurred in eggs and hepatopancreas during the first six days of depuration. During exposure to Cd and Zn combined (40 g Cd/L + 70 g Zn/L), tissue Zn levels responded as with Zn alone. In the presence of Zn, Cd concentration was doubled in the hepatopancreas, depressed by one-third in the carcass, and did not change in the other tissues. Increased amounts of Zn (up to 410 g Zn/L) had no effect on the Cd levels of the tissues except that the Cd level in the hepatopancreas was depressed, although the level was still greater than in the case of exposure to Cd alone. The possible role of metallothionein is discussed.     

Comparative toxicity of selenite and selenate to the amphipodHyalella azteca

Selenium contamination of aquatic ecosystems is rapidly becoming a concern throughout the United States, leading to a lowering of the freshwater selenium criteria by the U.S. Environmental Protection Agency from 35 g/L to 5 g/L measured as total selenium. However, considerable information indicates important differences in bioaccumulation and toxicity between the various selenium forms. We conducted a series of experiments to determine the comparative toxicity of selenite and selenate to the amphipodHyallela azteca. In 48 h, 96 h, and 240 h (10 d) LC50 tests, selenite was 2 to 4 times more toxic than selenate, the difference decreasing as exposure time increased. This difference in toxicity was even more pronounced in the 24 d reproductive bioassay, where selenite caused a significant decrease in number of young per female at 200 g/L while selenate had no effect up through 700 g/L (the highest concentration tested).     

Cytogenetic studies of herbicide interactions in vitro and in vivo using atrazine and linuron

The herbicides atrazine and linuron, found in Wisconsin's groundwater, were tested alone and in combination, both in vivo and in vitro, to determine their individual and combined genotoxic effects. Human lymphocytes exposed in vitro to either 1 g/ml linuron or 0.001 g/ml atrazine showed little chromosome damage, whereas significant chromosome damage was observed in lymphocytes simultaneously exposed to 0.5 g/ml linuron and 0.0005 g/ml atrazine, suggesting at least an additive model. In another experiment, mice were fed 20 g/ml atrazine, 10 g/ml linuron, or a combination of 10 g/ml atrazine and 5 g/ml linuron in their drinking water for 90 days, after which bone marrow cells and cultured splenocytes were examined for chromosomal damage. None of the treatment groups showed chromosome damage in bone marrow, whereas the cultured splenocytes demonstrated damage in all treatment groups. These experiments suggest that, prior to assessing the risk of a herbicide, it may be necessary to test it in combinations which mimic the mixtures which would occur under field conditions, such as in contaminated groundwater.     

Effects of cadmium on growth and bioaccumulation in the northwestern salamander Ambystoma gracile

Tests were conducted to determine the effects of cadmium (Cd) on survival, growth, and bioaccumulation in larvae and metamorphosed juveniles of the Northwestern salamander, Ambystoma gracile. A 96-h LC50 value of 468.4 g/L Cd was determined for 3-mo old larvae. Significant adverse effects of Cd (in water) on larval growth were observed at 227.3 g/L in a 10-day exposure and at 193.1 g/L Cd (LOAEL) in a 24-day exposure; no significant adverse effects were seen at 106.3 g/L Cd in the 10-day test and 48.9 g/L Cd (NOAEL) in the 24-day test. In the juvenile feeding tests, regurgitation of Cd-spiked food occurred at 5,701 and 2,458 g/g Cd, but not at 982 g/g. Cadmium tissue bioconcentration values up to 63 times the water concentration were seen in the water/larval tests. No bioaccumulation occurred in the larval and juvenile feeding tests, although similar tissue Cd levels were produced by both water and feeding exposures.The information in this document has been funded by the U.S. Environmental Protection Agency. It has been subjected to the Agency's peer and administrative review, and it has been approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Measurement of manganese amelioration of cadmium toxicity inChlorella pyrenoidosa using turbidostat culture

Cadmium (Cd) toxicity and amelioration of Cd toxicity by Mn were measured inChlorella pyrenoidosa, using turbidostat culture. The responses were measured in terms of the maximum specific growth rate, _max, of the populations. In turbidostat culture _max is a dependent variable that can be measured continuously. Cd (as CdCl₂· 2.5 H₂O) was added to control populations at a concentration of 1.8 M Cd. Toxicity was expressed after a 5 generation lag and resulted in a _max steady state 62% lower than the initial control after 2 generations. With continued Cd exposure, Mn (as MnCl₂ · 6H₂O) was then added stepwise to a concentration of 10.4 M Mn which caused a rapid, immediate increase in _max followed by linear increase until a steady-state plateau was reached at a _max 90% of control. The ameliorative response spanned 20 culture generations. After addition of Mn (10.4 M), cellular Cd concentration did not change and cellular Mn concentration increased. Increase in mean cell size accompanied Cd exposure and was significantly decreased when supplemented with 10.4 M Mn. Possible mechanisms of the amelioration are discussed.     

Blood toluene as a biological index of environmental toluene exposure in the “normal” population and in occupationally exposed workers immediately after exposure and 16 hours later

Blood toluene was measured in a group of 100 workers occupationally exposed to a mean 8-h environmental toluene concentration of 128 g/l (34 ppm), and in a group of 269 normal subjects without occupational exposure to toluene. The mean blood toluene of the workers at the end of the shift and the following morning, after 16 h, was 457 and 38 g/l, respectively. The normal subjects had a blood toluene level of 1.1 g/l. On the basis of the highly significant correlation between blood toluene and occupational exposure, it can be calculated that environmental toluene exposure of 188 and 377 g/l (50 and 100 ppm) gives end-of-shift blood toluene levels of 690 and 1390 g/l, respectively. The corresponding blood toluene levels on the following morning are 50 and 100 /l, respectively.     

Toxicity of aldicarb and fonofos to the early-life-stage of the fathead minnow

Flow-through early-life-stage (ELS) toxicity tests were conducted with the pesticides aldicarb (Temik^®) and fonofos (Dyfonate^®) to determine their effect on the survival and growth of fathead minnows. Concentrations of 78g/L of aldicarb and 16g/L of fonofos did not affect survival and growth. However, 156g/L of aldicarb and 33g/L of fonofos were lethal to larval-juvenile exposed for 30 days post-hatch. The maximum acceptable toxicant concentration (MATC) of aldicarb and fonofos for the fathead minnow is estimated to be between 78–156g/L and 16–33g/L, respectively. The corresponding chronic values (geometric mean of MATC values) would be 110g/L and 23g/L. Acute toxicity tests gave 96-hr LC50 values of 1370g aldicarb/L and 1090g fonofos/L. The acute-chronic ratio (96-hr LC50/chronic value) is 12 for aldicarb and 47 for fonofos.     

DDT Residues in samples of human milk,and in mothers' and cord blood serum,in a continental town in Croatia (Yugoslavia)*

Summary Concentrations of p,p'-DDE, p,p-DDD, and p,p-DDT were determined in 34 samples of human milk obtained 3–5 days after delivery and in 37 samples obtained at later times of lactation (up to 55 weeks). All samples contained p,p-DDE, but only several contained p,p-DDD and p,p-DDT. The concentrations of p,p-DDE were 31 g/l in the beginning of lactation and 53 g/l at later time intervals. The concentration ranges in both groups overlap almost completely and the difference in the mean values is not significant.Serum samples from 35 mothers and cord blood were also analyzed. All samples contained p,p-DDE, the concentrations being 18 g/l and 6.8 g/l in the mothers' and cord blood serum, respectively. Serum samples of 24 nonpregnant women contained the same amount of p,p-DDE (20 pg/1) as mothers' sera.All samples were collected in a continental town of Croatia (Yugoslavia) between 1977 and 1979. The concentrations of DDT residues were determined by gas chromatography, and two methods for extraction from milk were used and compared.This work was supported in part by the Environmental Protection Agency (USA) and the World Health Organization (Geneva)     

Belgian collaborative study of the in-vitro susceptibility of the Bacteroides fragilis group

The antimicrobial susceptibility of clinical isolates of the Bacteroides fragilis group obtained from nine large Belgian university and community hospitals was studied. Of the -lactam antibiotics tested, none were active against 100% of the isolates. Piperacillin was active against 93% of the strains at a breakpoint of 64 lag/ml. The percentage of isolates inhibited at 16 g/ml (and 32 g/ml) for the 7-alpha-methoxy antibiotics was: cefoxitin 84 [94]; latamoxef 87 [93]; and cefotetan 64 [79]. B. fragilis tended to be more susceptible to all -lactams than the other members of the group.Among the non -lactam antibiotics, the resistance rate for minocycline, doxycycline, clindamycin and erythromycin (at a breakpoint of 4 g/ml) were l%, 4%, 14% and 34%, respectively. Like the -lactams, clindamycin was less active against non B. fragilis species of the group.Chloramphenicol, metronidazole and tinidazole were still active against 100% of the isolates at their breakpoint values (8 lag/ml).     

Behavioral effects of waterborne carbofuran in goldfish

The effects of concentration (1, 10, 100 g/L) and duration (4, 8, 12 h) of exposure to carbofuran were assessed on the swimming activity, social interactions, and behavioral responses of goldfish to a flow (0.1 L/min) of water, with or without chironomids. Observations were also made on the behavioral responses of unexposed goldfish to a flow (0.1 L/min) of carbofuran-contaminated water. A 4-h exposure of goldfish 1 g/L carbofuran produced a significant increase in sheltering, burst swimming, and nipping. Responses were enhanced at 100 g/L. After a 12-h exposure, the behavioral effects of 1 g/L carbofuran were less apparent. However, burst swimming at 10 g/L, and sheltering, nipping and burst swimming at 100 g/L, were still significantly increased after a 12-h exposure to carbofuran. Grouping was not consistently affected by exposure conditions. Chemical attraction to a filtrate of chironomids was significantly reduced after the 4-h exposure to 1 g/L carbofuran. Decreased attraction to the food extract was less apparent after the 12-h exposure, except at 100 g/L carbofuran. A significant decrease in attraction to a flow of uncontaminated water was also observed after a 4-h exposure to 10 and 100 g/L carbofuran. Unexposed goldfish did not show avoidance reaction to a flow of carbofuran-contaminated water, even at a concentration (10 mg/L) exceeding the mean 96-h LC-50 in cyprinids (0.5–1 mg/L). However, at all concentrations tested (0.1, 1, 10 mg/L), goldfish quickly reacted to the introduction of the solution of carbofuran by increased burst swimming and nipping. These results are discussed in the light of the data concerning behavioral and neurotoxic effects of carbamate and organophosphorous insecticides in fish.     

Susceptibility of clinical isolates of campylobacter pylori to 24 antimicrobial and anti-ulcer agents

Forty-nine isolates of Campylobacter pylori were tested for their susceptibility to twenty antibiotics and four anti-ulcer agents by an agar dilution technique. Penicillin and amoxycillin were the most active drugs (MIC₉₀, 0.06 /ml); erythromycin, cefazolin, minocycline, ciprofloxacin, ofloxacin and gentamicin were sligthtly less active (MIC₉₀, 1 g/ml). Moderate activity was found for doxycyclin, rifampin, nitrofurantoin, norfloxacin, pefloxacin, enoxacin, paromomycin, metronidazole and tinidazole. All strains were resistant to trimethoprim (MIC > 512 g/ml). Nalidixic acid (MIC₉₀, > 256 g/ml) and colistin (MIC₉₀, > 64 gg/m1) had little to no activity. Of four anti-ulcer drugs, only bismuth subcitrate showed activity (MIC₉₀, 64 g./ml).Strains resistant to all 4-quinolones were found in patients who had previously received ofloxacin as part of a clinical trial aimed at eradication of C. pylori. These isolates remained susceptible to amoxycillin, tetracyclines and to other classes of antibiotics.Corresponding author.