Acute toxicity test with Daphnia magna: an alternative to mammals in the prescreening of chemical toxicity?

In this study, the association between the acute toxicity of 15 compounds to Daphnia magna, expressed as 24- and 48-h LC(50) values, and the corresponding oral LD(50) values for the rat was tested. Since there was evidence of a strong relationship between the two species, the sample was extended to 54 cases by including the values for acute toxicity to D. magna and rat of more chemicals published by other authors. Thus, a total of 54 data points were further used to ascertain the relationship between the acute toxicity of chemical compounds to D. magna and that to the rat. To summarize its validity, the D. magna test is more specific than sensitive as an indicator of toxicity to the rat. When it is used with a chemical that has a high probability of being very toxic to D. magna (LC(50)< 0.22 mg/L), the test provides considerable information if it is positive, virtually giving evidence of toxicity to the rat (with a probability of 0.83). On the other hand, a negative test (D. magna LC(50)>0.22 mg/L) has a probability of correctly assigning nontoxicity to the rat equal to 0.74. This study and results published by other authors provide good evidence of the applicability of using invertebrate tests as prescreening methods, thus considerably reducing the number of mammals required in toxicity testing.     

High tolerance of lampreys to Kepone® toxicity

Larval sea lampreys (Petromyzon marinus) were exposed to the organochlorine insecticide Kepone^® in freshwater solution in a continuous flow diluter system at 12 and 20°C. At 12°, the 36-hr LC50, 96-hr LC50, and incipient lethal concentrations were 1,100, 444 and 145 g Kepone/ L, respectively, while at 20°, the 96-hr LC50 was 414 g/L. These are the highest LC50 values for Kepone ever reported for a fish species. Rates at which larval lampreys accumulate and clear Kepone were measured at 12°C. The depuration rate constant (K_d: 0.13–0.46 per day) was the highest ever reported in a fish species, so rapid elimination may contribute to the exceptional ability of lampreys to survive acute Kepone poisoning. The uptake rate constant (K_u) was 450–650 per day, and the bioconcentration factor averaged about 1900. The most likely source of high tolerance of lampreys to Kepone is an ability to withstand high tissue levels: Lampreys survived body burdens of 500–600 g Kepone/g, exceeding all other known vertebrates. Technical difficulties associated with the use of Kepone solutions are discussed, such as precipitation and loss from solution through apparent volatilization.     

Comparative toxicity of two glyphosate formulations (original formulation of Roundup® and Roundup WeatherMAX®) to six North American larval anurans

The toxicity of two glyphosate formulations (the original formulation of Roundup? and Roundup WeatherMAX?) to six species of North American larval anurans was evaluated by using 96-h static, nonrenewal aqueous exposures. The 96-h median lethal concentration values (LC50) ranged from 1.80 to 4.22 mg acid equivalent (ae)/L and 1.96 to 3.26 mg ae/L for the original formulation of Roundup and Roundup WeatherMAX, respectively. Judged by LC50 values, four species were more sensitive to Roundup WeatherMAX exposures, and two species were more sensitive to the original formulation. Two of six species, Bufo fowleri (p < 0.05, F = 14.89, degrees of freedom [df] = 1) and Rana clamitans (p < 0.05, F = 18.46, df = 1), had significantly different responses to the two formulations tested. Increased sensitivity to Roundup WeatherMAX likely was due to differences in the surfactants or relative amounts of the surfactants in the two formulations. Potency slopes for exposures of the original formulation ranged from 24.3 to 92.5% mortality/mg ae/L. Thresholds ranged from 1.31 to 3.68 mg ae/L, showing an approximately three times difference in the initiation of response among species tested. For exposures of Roundup WeatherMAX, slopes ranged from 49.3 to 84.2% mortality/mg ae/L. Thresholds ranged from 0.83 to 2.68 mg ae/L. Margins of safety derived from a simulated direct overspray were above 1, except for one species in exposures of Roundup WeatherMAX. Laboratory data based on aqueous exposures are conservative because of the lack of environmental ligands; however, these tests provide information regarding the relative toxicity between these two Roundup formulations.     

Does sulfide or water hardness protect against chronic silver toxicity in Daphnia magna? A critical assessment of the acute-to-chronic toxicity ratio for silver

The protective effects of sulfide and water hardness against acute and chronic silver toxicity in Daphnia magna were assessed in the presence of food. Results showed that both sulfide and water hardness protected against lethal acute and chronic silver toxicity in terms of mortality. However, only sulfide showed a protective effect against the sub-lethal chronic silver effects on growth and reproduction. These findings suggest that both reactive sulfide and water hardness must be taken into account in the development of a chronic version of the Biotic Ligand Model (BLM) for waterborne silver. Furthermore, acute-to-chronic ratio values for silver toxicity showed that only small increases in toxicity are seen over the chronic exposure relative to the acute toxicity. Mortality is the most sensitive endpoint in moderately hard water and in the presence of sulfide. Reproduction, measured as the number of neonates produced per adult per reproduction day, is the most sensitive one in hard water in the absence of sulfide.     

Chronic toxicity and bioaccumulation of 2,5,2′,5′- and 3,4,3′,4′-tetrachlorobiphenyl and Aroclor® 1242 in the amphipodHyalella azteca

The addition of 100 (g/L of Aroclor^® 1242 (A1242) or 2,5,2,5-tetrachlorobiphenyl (TeCB) during 10 week chronic toxicity tests withHyalella azteca resulted in complete mortality. There were no effects on survival, growth, or reproduction after addition of 30 g/L. Toxic effects were observed at tissue levels of between 30 and 180 g/g on a wet weight basis, and tissue levels appear to be a better indicator of toxicity than levels in water. No toxic effects were observed after additions of up to 2,700 g/L of the coplanar congener 3,4,3,4-TeCB.H. azteca has the ability to avoid accumulating in excess of 140 g/g 3,4,3,4-TeCB. The amount taken up was proportional to the amount added in water up to 100 g/L, but was constant at higher additions, possibly accounting for its relatively low toxicity. The low toxicity of the coplanar congener, as compared to the non-coplanar 2,5,2,5-TeCB, is in direct contrast to the high toxicity of coplanar PCB congeners to mammals and may be associated with slower rates of aromatic hydrocarbon metabolism in amphipods. Polychlorinated biphenyl levels measured in amphipods from Lake Ontario are approximately 100-fold below levels associated with toxicity inH. azteca, but are above levels which, through biomagnification up the food chain, lead to salmonid residues in excess of 2 g/g, a tolerance limit for human consumption.     

Acute toxicity and hazard assessment of Rodeo®, X-77 Spreader®, and Chem-Trol® to aquatic invertebrates

The herbicide Rodeo^® provides waterfowl managers with an effective chemical tool for creating open water habitats in wetlands if its use does not adversely affect native invertebrate communities. The survival of caged Chironomus spp. (midge), Hyalella azteca (amphipod), Stagnicola elodes (pond snail), and Nephelopsis obscura (leech) was assessed in prairie pothole wetlands treated by air with a tank mixture of Rodeo^®, the surfactant X-77 Spreader^®, and the drift retardant Chem-Trol^® at a rate recommended for controlling cattails. Laboratory studies were then conducted to determine the acute toxicities of Rodeo^®, X-77 Spreader^®, and Chem-Trol^®, individually and in simulated tank mixtures, to the same invertebrates and to Daphnia magna in reconstituted water representative of these wetlands. There was no difference in the survival of caged invertebrates between treated and reference wetlands after 21 days. Based on nominal concentrations of the formulations, X-77 Spreader^® (LC50s=2.0–14.1 mg/L) was about 83–136 times more toxic than Rodeo^® (LC50s=218–1216 mg/L) to aquatic invertebrates. Chem-Trol^® killed 10% of the animals at 10,000 mg/L and 50% of the animals at 28,000 mg/L. Daphnia magna were more sensitive than the other species to X-77 Spreader^®, Rodeo^®, and the simulated Rodeo^® tank mixture (RTM). The joint toxic action of the RTM was additive for amphipods and midges, greater than additive for leeches, and was less than additive for daphnids. X-77 Spreader^® was the major toxic component in the RTM. Binary mixtures of X-77 Spreader^®, Rodeo^®, and Chem-Trol^® at tank mixture and equitoxic ratios also showed additive toxicity to amphipods. The use of Rodeo^® (applied as a tank mixture with X-77 Spreader^® and Chem-Trol^®) as a management tool in wetlands does not pose an acute hazard to native aquatic invertebrates because the concentrations of Rodeo^®, X-77 Spreader^®, and Chem-Trol^® found to be acutely toxic to these invertebrates were much higher than their expected or measured concentrations in water from wetlands treated with the RTM.     

Chronic toxicity studies of crude organic chemical pollutants,illustrated by studies with Aroclor® 1254

A stepwise regression statistical analysis was used to interpret results from chronic toxicity experiments. Advantage was taken of the independent buildup and decline of the constituents of the PCB mixture being tested (Aroclor^® 1254) to associate the concentrations with the induction of two microsomal oxidase systems, aniline hydroxylase and P-450. The concentration of 2,4,5,2′,4′,5′-hexachlorobiphenyl in the liver was shown to be associated with the latter.     

Field and laboratory studies to assess the effects of Vertimec(®) 18EC on Daphnia similis

The present study aimed to evaluate the interactions of the pesticide Vertimec(?) 18EC in aquatic ecosystems. In this respect, soil plots were contaminated with Vertimec(?) 18EC at the concentration indicated for strawberry crops (0.125L of solution m(-2)). After the contamination, torrential rainfall was simulated and the surface runoff was collected and transferred to mesocosm tanks in five treatments, run in triplicate: (1) control-C; (2) runoff from an uncontaminated plot-UR; (3) runoff from the plot contaminated with Vertimec(?) 18EC-CR; (4) direct application of Vertimec(?) 18EC in the water-V and (5) water samples gathered randomly to verify whether there was contamination between the mesocosms-RS. Water samples from these tanks were also submitted to ecotoxicological tests with Daphnia similis and analyses to evaluate the limnological characteristics, in five collection periods over 10 days (240h). Physical and chemical differences were observed in the water samples, mainly related to increased turbidity, suspended solids and nutrients (nitrogen and phosphate forms). Acute toxicity was observed for the direct application treatment for the entire experimental period, and in some periods for the CR treatment (from 48h to 168h). The results obtained suggest that the pesticide did not fully degrade during the study period (10 days) in the direct application treatment, demonstrating that the presence of other substances in the commercial formulation contribute to the maintenance of toxicity. This represents a potential risk for aquatic ecosystems in areas adjacent to where the chemical is applied.     

Toxicity of Guthion® and Guthion® 2S to Xenopus laevis embryos

The development of Xenopus laevis (African clawed frog) embryos exposed to the pesticide Guthion^® (technical grade) and Guthion^® 2S (commercial formulation) was evaluated in modified Frog Embryo Teratogenesis Assay—Xenopus (FETAX) tests. The embryos were exposed to five or six increasing concentrations of pesticide in 10- and 100-ml exposure volumes of test solution for 96 h. Embryos exposed in 10-ml volumes of Guthion exhibited increased mortality, increased deformation, and decreased size as compared to those exposed in 100-ml volumes. LC50s for embryos exposed in the 10-ml Guthion tests ranged from 6.1 to 6.3 mg/L as compared to 10.6 to 11.9 mg/L for those in the 100-ml tests. The percentage of deformities at 3 mg/L Guthion in test survivors in 10-ml tests ranged from 73 to 89%, while in the 100-ml tests less than 2% were deformed at the same concentration. Mean control embryo lengths at test completion were 8.2 and 10.6 mm, respectively, for 10- and 100-ml tests. The LC50 for embryos in 100 ml Guthion 2S was 1.6 mg/L active ingredient, indicating a much greater toxicity of the commercial formulation. NOAEL (No Observed Adverse Effect Level) values for Guthion and Guthion 2S ranged from 0.48 to 7.96 mg/L, depending upon basis (length, deformity, mortality) and pesticide formulation, and were many times greater than the existing water quality criterion of 0.01 g/L.     

Effects of Kepone® on the sheepshead minnow in an entire life-cycle toxicity test

A life-cycle toxicity test with the estuarine sheepshead minnow (Cyprinodon variegatus) and the insecticide Kepone^® (chlordecone) in seawater showed that the maximum acceptable toxicant concentration (MATC) lies between 0.074 and 0.12 g Kepone/L, based on reduced standard length of progeny at 0.12g/L and higher concentrations. The application factor range (MATC/96-hr LC50) for sheepshead minnows exposed continuously to Kepone is from 0.001 to 0.002. Other adverse effects of Kepone exposure were: External signs of poisoning in fish exposed to concentrations 0.074g/L, fatty degeneration of the liver and histological evidence of vertebral damage in some fish exposed to 0.78g/L, reduced growth of parental fish at 0.39 and 0.78g/L, reduced fecundity and fertility of eggs at 0.78g/L, and reduced survival of embryos produced by fish exposed to 0.78g/L. Average bioconcentration factors (concentration in tissue ÷ average measured concentration in water) ranged from 2,600 for 21-day-old juveniles to 7,600 for adult males. ^®Registered trademark, Allied Chemical Corp., 40 Rector St., New York, NY 10006. Mention of trade names or commercial products does not constitute endorsement by the Environmental Protection AgencyGulf Breeze Contribution No. 425     

Development and Sensitivity of a 12-h Laboratory Test with Daphnia magna Straus Based on Avoidance of Pulp Mill Effluents

Studies on avoidance of contaminants by aquatic organisms verified that such behavior may have crucial ecological implications. Yet, avoidance tests have not been considered in ecological risk assessments. This study aimed at developing a short-term test with Daphnia magna Straus based on avoidance of pulp mill effluents and at comparing its sensitivity to the standard 21 d D. magna reproduction test. The avoidance effective dilution values (12 h EDil20 and EDil50) were as sensitive as the 21 d EDil20 and EDil50 values for reproduction. Therefore, this easily standardizable short-term test can be recommended as a valuable complementary tool in ecological risk assessments.     

In vitro development of parthenogenetic eggs: a fast ecotoxicity test with Daphnia magna?

In the present study, the authors investigated and defined development stages of Daphnia magna eggs that could be potential endpoints for sublethal toxicity tests with in vitro parthenogenetic egg cultures. Such an "egg test" could be a cost-effective alternative to the classic 21-day test with D. magna. Three main stages of embryonic development were considered: release of the egg external membrane, release of the internal membrane, and separation of the caudal spine. The first embryonic stage was attained approximately 30 h after transfer of eggs from ovaries to the brood chamber (considered as time zero), the second stage at 48 h, and the third stage at 68 h. Embryonic development was considered completed with the caudal spine separation. Thereafter, juveniles were able to swim in the water column. Egg mortality, duration of each egg stage, egg diameter, and egg abnormalities were investigated as potential endpoints. In vitro tests were carried out with several toxicants (DBS, 3,4-DCA, cadmium, and copper) and with acid mine drainage, sensitivity generally being higher than with the accepted chronic 21-day test with D. magna.     

Rotarix® and RotaTeq® administration to preterm infants in the neonatal intensive care unit: Review of available evidence

Rotavirus (RV) is the leading cause of severe acute gastroenteritis (GE) in infants worldwide. Several vaccines against RV were developed to reduce disease burden, hospitalization rates and health utilization costs. RV GE is a serious disease in preterm (PT) infants, and the administration of RV vaccine to these at-risk subjects at the proper time could have great clinical relevance. However, most data on the efficacy and safety of RV vaccinations were collected in healthy full-term infants, and few studies investigated PT infants. The lack of studies in PT infants may explain why neonatologists in several neonatal intensive care units (NICUs) do not follow the official recommendations, which indicate that RV vaccine may be administered in hospitals. Increasing neonatologists’ knowledge on the efficacy and safety of RV vaccines and defining PT candidates for vaccination and the necessary precautions are extremely important to avoid potential vaccine virus transmission and improve RV vaccination coverage in PT infants. Further studies should analyse the impact of vaccination of PT infants of different gestational ages and various clinical histories in stable conditions in the NICU with a careful monitoring of adverse events to the vaccine and RV GE occurrence. Only data that confirm the efficacy and safety of RV vaccines in large numbers of PT infants with different characteristics will convince neonatologists to use RV vaccines in PT infants hospitalized in NICUs.     

Improvement in the GC–MS method for determining urinary toluene-diamine and its application to the biological monitoring of workers exposed to toluene-diisocyanate

Objectives: To develop a simple and sensitive GC–MS method for determining toluene-diamine (TDA) in urine and to apply the method for biological monitoring of workers exposed to toluene-diisocyanate (TDI). Methods: After acid hydrolysis of 0.1 ml of urine, diluted tenfold with water, for 1.5 h, the free TDA formed was extracted with dichloromethane, and the heptafluorobutyric anhydride derivative was determined by GC–MS. We applied the method to the biological monitoring of 18 workers who were using an 80:20 mixture of 2,4-TDI and 2,6-TDI. Results: 2,6-TDA and 2,4-TDA were simply determined in 7 min by GC–MS. TDA levels in post-shift urine were well correlated with personal exposure levels of TDI. The correlation was improved by correction with creatinine or specific gravity in the 2,6-isomer, but not in the 2,4-isomer because of low exposure levels. From the correlation equation, the 2,6-TDA level (corrected with creatinine), corresponding to the TDI level of 5 ppb, was calculated to be 31.6 g/g Cre. TDAs in pre-shift urine also correlated significantly with the personal exposure levels of TDIs, although the slope of the correlations for pre-shift samples was 60%–70% of those for post-shift samples. The correlation between 2,4-TDA and 2,6-TDA levels was significant, although the levels of the 2,4-isomer were less than one-tenth of the 2,6-isomers in both air (personal exposure) and urine. Conclusion: The present method is simple and practicable and can be useful for biological monitoring of TDI workers.     

Qualitative Research to Explore the Patient Experience of X-Linked Hypophosphatemia and Evaluate the Suitability of the BPI-SF and WOMAC® as Clinical Trial End Points

Background

X-linked hypophosphatemia (XLH) is a rare genetic disorder characterized by renal phosphate wasting and defective bone mineralization. Symptoms include bone pain, joint pain, stiffness, and fatigue. Published evidence regarding the patient experience of XLH is sparse and no XLH-specific outcome measures have been validated.