Use of the Species Sensitivity Distribution Approach to Derive Ecological Threshold of Toxicological Concern (eco-TTC) for Pesticides

The species sensitivity distribution (SSD) calculates the hazardous concentration at which 5% of species (HC5) will be potentially affected. For many compounds, HC5 values are unavailable impeding the derivation of SSD curves. Through a detailed bibliographic survey, we selected HC5 values (from acute toxicity tests) for freshwater aquatic species and 129 pesticides. The statistical distribution and variability of the HC5 values within the chemical classes were evaluated. Insecticides are the most toxic compounds in the aquatic communities (HC5 = 1.4x10−03 µmol L−1), followed by herbicides (HC5 = 3.3 x10−2 µmol L−1) and fungicides (HC5 = 7.8 µmol L−1). Subsequently, the specificity of the mode of action (MoA) of pesticides on freshwater aquatic communities was investigated by calculating the ratio between the estimated baseline toxicity for aquatic communities and the HC5 experimental values gathered from the literature. Moreover, we proposed and validated a scheme to derive the ecological thresholds of toxicological concern (eco-TTC) of pesticides for which data on their effects on aquatic communities are not available. We proposed eco-TTCs for different classes of insecticides, herbicides, and fungicides with a specific MoA, and three eco-TTCs for those chemicals with unavailable MoA. We consider the proposed approach and eco-TTC values useful for risk management purposes.

Anthelmintic effect of Portulaca oleracea Linne (Portulacacea) against gastrointestinal parasites Haemonchus contortus Rudolphi and toxicity screenings

Background: The resistance of gastrointestinal worms to synthetic anthelmintics (Levamisole) leads us to highlight the Cameroonian pharmacopoeia. The main objective of the present work is to look for an alternative treatment for haemonchosis, based on active secondary metabolites, from Portulaca oleracea, with less or no side effects and accessible to all. Methods: The Haemonchus contortus cycle test was performed at varying concentrations. Levamisole and PBS were the positive and negative controls respectively. Phytochemical screening was performed by standard staining and precipitation methods. Acute and sub-acute toxicity tests of Portulaca oleracea EA were performed according to OECD 425 and 407 respectively. Results: EM at 48 h of incubation inhibited eggs with an LC50 of 3.44. There was more larvicidal effect of ME with an LC50 value of 3.54 at 48 h incubation. At 24 h of incubation at the final concentration of 1000 µg/mL the anthelmintic effect of EA, ME and levamisole were noted with LC50 values of 0.057, 0.096, and 0.069 respectively. Phytochemical screening revealed the presence of some secondary metabolites in EA and ME of Portulaca oleracea. The result of the assays shows that ME is richer in total polyphenol (50.884 mg EAG/g DM) and flavonoids (5.688 mg RE/g DM) compared to EA which has (12.998 mg EAG/g DM) and (1.847 mg EC/g DM) respectively. However, there are more tannins in EA (5.688 mg RE/g DM) compared to ME (1.847 mg EC/g DM). The acute and subacute toxicity test showed no toxicity in mice and rats respectively. Conclusion: In view of the above, Portulaca oleracea possesses anthelmintic effects on the parasite Haemonchus contortus and is not toxic at the experimental therapeutic dose, which may open a way for the searching of a new anthelmintic drug. Keywords: Haemonchus contortus; Portulaca oleracea; Levamisole; Phytochemical screening; Toxicity.

Systematic Safety Evaluation of Cold Plasma-Activated Liquid in Rabbits

Plasma-activated liquid (PAL) can effectively and selectively kill various types of cancer cells both in superficial and deeper tumors. As a promising novel approach to oncotherapy, the safety of PAL is essential in the clinic but has not been thoroughly assessed. In myeloma and blood tumors, the pathogenesis is in the bone marrow cavity. We have therefore evaluated the safety of PAL in New Zealand rabbits by intra-bone marrow injection, and provide a basis of further clinical research and application of PALs. In this study, both a plasma jet and plasma surface were used to treat saline solution, phosphate-buffered solution, and cell culture medium, to produce PAL. Then, oscillograms and optical emission spectra were evaluated to characterize the plasma discharge. Acute toxicity tests and safety evaluation studies were conducted by intra-bone marrow injection of PAL into New Zealand rabbits, while control rabbits received saline only. Body weight, vital organ coefficient, organ appearance, organ histopathology, blood cell and hemoglobin parameters, and blood biochemical indicators were tested on the 30th day after injection. We found that there was no mortality or loss of mobility throughout the experimental period. Acute toxicity tests showed that there were no PAL-related side effects in rabbits receiving the maximum dose of 700 μL PAL. PAL treatments did not affect body weight, organ coefficient, organ appearance, organ histopathology, or blood biochemical indicators. However, the percentage of lymphocytes decreased while the percentage of neutrophil granulocytes increased compared with the control group. In summary, our results indicate that PAL can be safely injected into bone marrow of New Zealand rabbits without significant toxicity.

Anti-nociceptive, anti-inflammatory and antipyretic activities of the ethanol root bark extract of Salacia lehmbachii in rats and mice

Background: The decoction of the roots of Salacia lehmbachi is used in traditional medicine for the treatment different diseases such as malaria pains diabetes and microbial infections.Methods: Phytochemical screening and oral acute toxicity tests were carried out on the ethanol root extract of the plant. Anti-nocicetive activity using acetic acid induced writhing and tail immersion method in mice, anti-inflammatory activity using carrageenan induced paw oedema in rats and xylene induced ear oedema test in mice and antipyretic activity using Brewer’s yeast and D-amphetamine induced pyrexia in rats were determined at 50 mg/kg, 100 mg/kg and 200 mg/kg doses of the root extract.Results: The ethanol root extract contain alkaloids, saponins, tannins, flavonoids, terpenoids, steroids and cardiac glycosides. The oral acute toxicity tests was found to be greater than 5000 mg/kg. The root extract and the standard drug (Aspirin) significantly (p<0.05 and p<0.01) decreased the number of writhes caused by acetic acid. The extract and morphine significantly (p<0.05 and p<0.01) prolonged reaction time in tail immersion model. The extract produced significant (p<0.05 and p<0.01) dose dependent inhibition of oedema which was comparable to aspirin in carrageenan induced paw oedema model. The root extract also demonstrated significant (p<0.05 and p<0.01) effect in xylene induced mouse ear oedema test compared to dexamethasone. The extract significantly decreased high temperature in both Brewer’s yeast and d-amphetamine induced pyrexia.Conclusions: Findings show that S. lehmbachii may provide a good source of plant compounds with analgesic, anti-inflammatory and antipyretic activities.

The Biodegradation of Dispersed Oil Does Not Induce Toxicity

ABSTRACT The acute toxicity of dispersed oil is well understood, and oil dilutes to levels below those of acute concern within hours of dispersion whether oil is dispersed by waves or by lower energy turbulence in the presence of chemical dispersants. Once dispersed, the hydrocarbon components of the spilled oil are degraded promptly by the native microbes in seawater, typically with an apparent half-life of 7–30 days even under Arctic conditions. Nevertheless, concern has been raised that this biodegradation might increase the oil's acute toxicity by generating and releasing toxic by-products. We show here, using Americamysis bahia as the test species, that this does not occur when dispersed oil is present at environmentally-relevant concentrations (initially 3 ppm oil dispersed with Corexit 9500 at a dispersant to oil ratio of 1:20). The guidelines for this toxicity test mandate a temperature of 26 ± 1C, rather warmer than the temperature of collection of the seawater from the New Jersey shore that we used as our experimental medium, so it is not surprising that biodegradation was especially rapid with a half-life for the loss of detectable hydrocarbons of approximately 4 days. We conducted sequential 4-day acute toxicity tests for 20 days, by which time the indigenous microorganisms had removed almost 80% of the detectable hydrocarbons in the lightly weathered crude oil. We saw no mortality in any of the five sequential tests.

A Comprehensive Assessment of the Safety of Blautia producta DSM 2950

In recent years, Blautia has attracted attention for its role in ameliorating host diseases. In particular, Blautia producta DSM 2950 has been considered a potential probiotic due to its ability to mitigate inflammation in poly(I:C) induced HT-29 cells. Thus, to promote the development of indigenous intestinal microorganisms with potential probiotic function, we conducted a comprehensive experimental analysis of DSM 2950 to determine its safety. This comprised a study of its potential virulence genes, antibiotic resistance genes, genomic islands, antibiotic resistance, and hemolytic activity and a 14-day test of its acute oral toxicity in mice. The results indicated no toxin-related virulence genes in the DSM 2950 genome. Most of the genomic islands in DSM 2950 were related to metabolism, rather than virulence expression. DSM 2950 was sensitive to most of the tested antibiotics but was tolerant of treatment with kanamycin, neomycin, clindamycin, or ciprofloxacin, probably because it possessed the corresponding antibiotic resistance genes. Oral acute toxicity tests indicated that the consumption of DSM 2950 does not cause toxic side effects in mice. Overall, the safety profile of DSM 2950 confirmed that it could be a candidate probiotic for use in food and pharmaceutical preparations.

Acute toxicity tests and dyeing potentials of three azo dyes from Pyocyanin, produced by Pseudomonas aeruginosa from farmlands

The admiration for colours by man has made dyes to have very useful applications on a great variety of materials. Pyocyanin (PCN) or 5-methyl-1-hydroxyphenazine, a phenazine derivative biosynthesized by Pseudomonas aeruginosa isolated from the stressed soil of a farmland at Awka was used to prepare three azo dyes namely, pyocyanin azophenol, pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol. The PCN was treated with SOCl2 to convert it to the chloro analogue. Treatment of chloro analogue with NaCN in ethanol and subsequent acid hydrolysis gave the carboxylic acid from which the amide was obtained after treatment with (NH4)2CO3 and heat. The amide was converted to the amine by Hoffman’s amide degradation. The amine was diazotized and coupled with phenol, 1-naphthol and 2-naphthol to give the three azo dyes respectively. UV-VIS and infrared spectra of the compounds agreed with the assigned structures. Acute Toxicity (LD50) tests showed the compounds to be reasonably non-toxic. Dyeing potentials of the Pyocyanin (PCN), PCN azophenol, PCN azo-1-naphthol and PCN azo-2-naphthol by mordant dyeing on cotton, silk and nylon textile materials showed them to have blue, dark green, purplish-brown and red colours respectively. The dyes were reasonably fast to light, washing, rubbing, alkali and acid. Pyocyanin, Pyocyanin azophenol, Pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol produced from Pseudomonas aeruginosa isolated from farmland soil can be used effectively to dye cotton, silk and nylon textile materials.

The Toxic Effects of Antibiotics on Freshwater and Marine Photosynthetic Microorganisms: State of the Art

Antibiotic residues have been commonly detected worldwide in freshwater, estuarine, and marine ecosystems. The review summarizes the up-to-date information about the toxic effects of over 60 antibiotics on nontarget autotrophic microorganisms with a particular focus on marine microalgae. A comprehensive overview of the available reports led to the identification of significant knowledge gaps. The data on just one species of freshwater green algae (Raphidocelis subcapitata) constitute 60% of the total information on the toxicity of antibiotics, while data on marine species account for less than 14% of the reports. Moreover, there is a clear knowledge gap regarding the chronic effects of antibiotic exposure (only 9% of studies represent exposition time values longer than 7 days). The review summarizes the information on different physiological endpoints, including processes involved in photosynthesis, photoprotective and antioxidant mechanisms. Currently, the hazard assessment is mostly based on the results of the evaluation of individual chemicals and acute toxicity tests of freshwater organisms. Future research trends should involve chronic effect studies incorporating sensitive endpoints with the application of environmentally relevant concentrations, as well as studies on the mixture effects and combined environmental factors influencing toxicity.

Seasonal Response of Daphnia pulex to Cyanobacterial Extracts at Different Temperatures in Valle de Bravo Reservoir (Mexico)

Valle de Bravo reservoir supplies drinking water to 40% of Mexico City. Here we present data on the population growth and life-table demography of the cladoceran Daphnia pulex, cultured at temperatures of 20 °C and 25 °C and with different concentrations of the crude extracts from blooms of Microcystis aeruginosa, collected in January, and Woronichinia naegeliana, collected in September. We hypothesized that Daphnia pulex would be more sensitive at the higher temperature and to toxins from W. naegeliana as these blooms have been shown to be more toxic to rotifers. We extracted the toxins and conducted acute toxicity tests at eight concentrations of microcystins at 20 °C. The LC50 was 26.8 µg/L and 11.5 µg/L, respectively, for Microcystis and Woronichinia samples. The chronic toxicity tests included population growth and life-table demography studies at 5 and 10% of the LC50 concentration, at 20 °C and 25 °C. Four replicates for each of the three treatments, which consisted of treatments with low and high cyanotoxin levels and a control without cyanotoxins, were set up. The population growth rate ranged from 0.18 to 0.42 d−1 on the extracts from M. aeruginosa (January) and from 0.2 to 0.31 on extracts from W. naegeliana. Daphnia, being better adapted to cooler temperatures, was more adversely affected at 25 °C than 20 °C. The adverse effect of cyanobacterial extracts was greater from Microcystis than Woronichinia blooms. The tolerance of Daphnia pulex to cyanotoxins depends on the bloom-forming species and the temperature.