Effects of the veterinary pharmaceutical salinomycin and its formulation on the plant Brassica rapa.

Veterinary pharmaceuticals are emerging contaminants found throughout the environment, and their presence and effects are a matter of concern. The purpose of this study was to compare the phytotoxicity of salinomycin (pure compound = 96 %) and Sacox 120 (formulated product = 120 g salinomycin/kg) to the plant species Brassica rapa as well as to investigate salinomycin persistence in soil. Calculated EC/IC(50) values for salinomycin and Sacox 120 were 1.10 and 2.88 and 2.19 and 18.03 mg/kg, respectively, based on salinomycin concentration. For exposure of B. rapa to salinomycin, significant adverse effects were observed for growth end points at the greater concentrations. For the reproduction end point (i.e., number of buds), as well as root length and wet mass, significant differences were observed at the lower concentrations (stimulating growth) and adverse effects at the greater concentrations. This study confirmed that the toxic effects of Sacox 120 are attributable to the active ingredient salinomycin. Liquid chromatography-electrospray ionization-mass spectrometry analyses confirmed that exposure concentrations of salinomycin were 90 and 83 % of the nominal concentrations, respectively, in the soils amended with either pure or formulated product. At the end of the experiment, after 14 days, salinomycin concentrations for both tests (salinomycin and Sacox 120) decreased to 6.2 and 5.8 % of the nominal exposure concentrations, respectively. Detected salinomycin concentrations in plant shoots ranged from 3.47 to 41.0 ng/g dry shoot. This study shows the importance of using plants as tools to evaluate environmental risk and as a bridge to relate environment and human health risks.

Ecotoxicity of aged uranium in soil using plant, earthworm and microarthropod toxicity tests.

Discrepancies about probable no effect concentrations (PNEC) for uranium in soils may be because toxicity tests used freshly contaminated soils. This study used 3 soils amended with a range of uranium concentrations 10 years previously. The toxicity tests with northern wheatgrass (Elymus lanceolatus); earthworm (Eisenia andrei) were not affected below ~1,000 mg U kg(-1), and the soil arthropod Folsomia candida was not affected below ~350 mg U kg(-1). Survival of Orthonychiurus folsomi was diminished 20% (EC(20)) by ~85-130 mg U kg(-1), supporting a PNEC in the range of 100-250 mg U kg(-1) as derived previously.

Chronic toxicity of a pure and technical grade pentachlorophenol to Daphnia magna.

Chronic toxicity test procedures (static, with renewal) were used to determine the chronic toxicity of sublethal concentrations of a technical formulation of pentachlorophenol (PCP) and pure pentachlorophenol to Daphnia magna. Test organisms 48 +/- 12 h old were exposed for their entire lifespan (i.e., until death) to 0.01, 0.05, 0.1 and 0.5 mg technical PCP/L and 0.01, 0.087 and 0.1 mg pure PCP/L. Criteria used to assess chronic toxicity were mean time to appearance of the primiparous instar in the brood chamber, mean number of days to release of the first brood, mean number of broods produced per female, mean brood size per female, mean number of reproductive days, mean number of young produced per reproductive day per female and survivorship. Pentachlorophenol differentially affected maturation and reproduction but not survivorship or longevity. Mean number of broods produced per daphnid, length of the reproductive period, longevity and survivorship were insensitive criteria relative to mean time to appearance of the primiparous instar, time to release of first brood, brood size, and number of young produced per daphnid per reproductive day. Generally, there was little difference in toxicity of the three concentrations of pure PCP, for they significantly reduced mean brood size and rate of reproduction of young and significantly but differentially affected maturation. Technical PCP, at the highest concentration of 0.5 mg/L, significantly reduced mean brood size and the rate of production of young, and significantly delayed both time to appearance of the primiparous instar and release of the first brood. When differences in toxicity occurred, generally, pure PCP was more toxic than comparable concentrations of technical PCP. Although enhanced maturation was observed there was no compensatory reproduction.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of acidification on the accumulation and toxicity of metals to freshwater invertebrates.

This paper reviews the literature to determine if lowered water pH (a) affects metal bioaccumulation in freshwater invertebrates, (b) enhances the toxicity of a given metal, and (c) increases waterborne metal concentrations to levels toxic to invertebrates. The elements considered are mercury, lead, cadmium and aluminum. The available evidence suggests that of these elements only mercury is biomagnified in aquatic foodchains. The bioaccumulation of all these elements is influenced by water pH, but data concerning invertebrates is meagre for mercury and lead. The effect of pH on mercury and lead toxicity to invertebrates is unclear and may be largely species specific. Cadmium toxicity is reduced by lower pH, while aluminum toxicity to invertebrates is markedly higher due to changes in aluminum speciation at low pH.

Acute toxicity of pure pentachlorophenol and a technical formulation to three species of Daphnia.

The acute toxicity of a technical formulation of pentachlorophenol (PCP) and pure pentachlorophenol to three age classes of Daphnia magna, and adult D. pulex and D. galeata mendotae was determined by static toxicity tests. The influence of a number of factors on toxicity of PCP was also examined. The 48-hr LC50 estimates for adult daphnids of the three species exposed to pure PCP were 1.78, 4.59 and 0.51 mg/L, respectively, while those for the technical formulation were 2.57, 3.66 and 0.33 mg/L, respectively. There was little difference in toxicity between the technical and pure PCP; however, toxicity of both forms of PCP was influenced by duration of exposure, age (and/or size) and species of test organism and pH of the test solution. Pentachlorophenol caused a toxic response over a very narrow range of concentrations, with the greatest response occurring immediately between 0 and 24 hr. Pure PCP was equally toxic to all age classes of D. magna but susceptibility to technical PCP decreased with maturation. D. g. mendotae was ten times more sensitive than D. pulex to PCP. Pure PCP was significantly more toxic to D. magna at pH 5.5 than 7.0 with mean 48-hr LC50 values of 0.082 and 1.78 mg PCP/L, respectively. At 12 degrees C, the toxicity of both forms of PCP to D. g. mendotae and D. pulex did not differ significantly from that at 20 degrees C; however, technical PCP was significantly more toxic to D. magna at 12 degrees C for an exposure duration of 48 hr.(ABSTRACT TRUNCATED AT 250 WORDS)