A battery of in silico models application for pesticides exerting reproductive health effects: Assessment of performance and prioritization of mechanistic studies

Given the high attention to endocrine disrupting chemicals (EDC), there is an urgent need for the development of rapid and reliable approaches for the screening of large numbers of chemicals with respect to their endocrine disruption potential. This study aimed at the assessment of the correlation between the predicted results of a battery of in silico tools and the reported observed adverse effects from in vivo reproductive toxicity studies. We used VirtualToxLab (VTL) software and the EndocrineDisruptome (ED) online tool to evaluate the binding affinities to nuclear receptors of 17 pesticides, 7 of which were classified as reprotoxic substances under Regulation (EC) No 1272/2008 on the classification, labelling and packaging of substances and mixtures (CLP). Then, we aligned the results of the in silico modelling with data from ToxCast assays and in vivo reproductive toxicity studies. We combined results from different in silico tools in two different ways to improve the characteristics of their predictive performance. Reproductive toxicity can be caused by various mechanisms; however, in this study, we demonstrated that the use of a battery of in silico tools for assessing the binding to nuclear receptors can be useful for identifying hazardous compounds and for prioritizing further studies.

Acute inhalation toxicity of aerosolized electrochemically generated solution of sodium hypochlorite

OBJECTIVE

The objective was to determine the inhalation toxicity of the electrochemically generated sodium hypochlorite solution after its single administration to laboratory animals in the form of a highly dispersed aerosol.

MATERIALS AND METHODS

The study has been conducted according to the OECD Test Guideline №403 'Acute Inhalation Toxicity.' Laboratory animals were exposed to inhalation of an aerosol containing 1.7 ± 0.13 mg/m³ of active chlorine. The hematological and biochemical parameters of the blood of experimental animals have been determined, as well as specific parameters: the activity of cathepsins B and L, catalase, and α1-antitrypsin. Histological study of the lungs of animals has been carried out.

RESULTS

During inhalation and 14 days after it, no death of the animals was observed; the behavior, appearance, and weight gain did not differ from the control group. There were no significant deviations in hematological parameters, except the decrease in the level of platelets. The biochemical study showed slight changes in the activity of alkaline phosphatase and aspartate aminotransferase on the 1st day after inhalation; these parameters returned to normal within 14 days of observation. Specific biochemical parameters did not show the development of oxidative stress. No specific histological pathologies of lung tissue have been found.

CONCLUSIONS

Thus, the studied electrochemically generated sodium hypochlorite solution under single inhalation exposure in aerosol form practically does not cause a toxic effect. The data obtained allow classifying such solution to the 4th (or even 5th - after additional studies) class of toxicity in accordance with Globally Harmonized System of Classification and Labeling of Chemicals.

EFFECT OF 2,6-DIMETHYLPYRIDINE-N-OXIDE ON THE SEVERITY OF CYTOGENETIC EFFECTS INDUCED BY DIOXIDINE IN BONE MARROW CELLS OF MICE

Objective - to study the ability of 2,6-dimethylpyridine-N-oxide to modify the cytogenetic effects in mouse bone marrow cells caused by the pro-oxidant mutagen Dioxidine. The cytogenetic activity and mutagen-modifying effect of the plant growth regulator 2,6-dimethylpyridine-N-oxide (Ivin) were studied by the method of accounting for chromosomal aberrations in the bone marrow cells of CD-1 mice (males) with a single joint exposure with Dioxidine. Ivin was administered single orally in the form of an aqueous solution at doses of 710, 71, and 0.7 mg/kg bw, which corresponds to 1/2, 1/20, 1/2000 of LD50 after intraperitoneally administered of Dioxidine at a dose 100 mg/kg. The animals of the positive control group were treated Dioxidine intraperitoneally at a dose of 100 mg/kg bw. Intact animals (negative control group) were orally administered purified, UV-sterilized, deionized water. It was shown that when combined with Dioxidine, Ivin at doses of 710, 71, and 0,7 mg/kg bw significally reduced the frequency of metaphases chromosome aberrations, relative to positive control by 55,56%, 66,70%, and 74,08% respectively. No multi-aberrant and polyploid cells were observed. In all variants of the experiment, only chromatid-type chromosome aberrations with single fragments were detected in the spectrum of chromosome aberrations. The severity of this effect had an inverse dose dependence: with a decrease in the dose of Ivin, the cytogenetic effects of Dioxidine decreased to a greater extent than with high doses of Ivin. The high antimutagenic effect of Ivin was confirmed, which is expressed to a greater extent when it is combined with Dioxidine than with Cyclophosphamide. These findings may be associated with the genoprotective effect of Ivin, due to the stabilization of membranes and its antioxidant effect.

[; INFLUENCE OF N-OXIDE-2,6-DIMETHYLPYRIDINE ON THE EXPRESSION OF CYTOGENETIC EFFECTS INDUCED BY CYCLOPHOSPHAMIDE IN MOUSE BONE MARROW CELL]

Objective - to study the ability of N-oxide-2,6-dimethylpyridine to modify the cytogenetic effects in mouse bone marrow cells caused by an alkylating antitumor cytostatic cyclophosphamide.; The cytogenetic activity and mutagen-modifying effect of the plant growth regulator N-oxide-2,6-dimethylpyridine (Ivin) were studied by the method of accounting for chromosomal aberrations in the bone marrow cells of CD-1 mice (males) with a single joint exposure to cyclophosphamide. In the first variant of the research, Ivin was administered single orally in the form of an aqueous solution at doses of 710, 71, 7.1, 0.7, and 0.07 mg/kg bw, which corresponds to 1/2, 1/20, 1/200, 1/2000 and 1/20000 from LD50. In the second variant - Ivin was administered together with Cyclophosphamide (Ivin - in the same way as in the first research variant, cyclophosphamide was administered intraperitoneally at a dose of 40 mg/kg bw the same as the positive control group). Intact animals (negative control group) were orally administered purified, UV-sterilized, deionized water.; It was shown that with isolated administration of Ivin in the studied doses did not show mutagenic activity. When combined with Cyclophosphamide, Ivin at a dose of 710 mg/kg bw did not induce the frequency of metaphases with chromosome aberrations and at a dose of 71 mg/kg bw reduced the frequency of metaphases with chromosome aberrations by 1.8 times in comparison with the positive control. In both of these dose groups, Ivin reduced the number of chromatid-type aberrations and polyploid cells but increased the number of multi-aberrant cells. This is probably due to the additional chemical load and physicochemical state of the Ivin molecule. When combined with Cyclophosphamide, Ivin at low dose levels (7.1, 0.7 and 0.07 mg/kg bw) significantly reduced the frequency of metaphases with chromosome aberrations (by 55.7%, 62.9% и 72.9%, respectively), the amount of chromatid-type aberrations, polyploid, and multi-aberrant cells. This may be due to the gene protective effect of Ivin, because of the stabilization of membranes and its antioxidant effect.

Differences in classification for skin corrosion/irritation in EU and Ukraine: Case study of alternative (in vitro and in silico) methods application for classification of pesticide active ingredient imazamox

In Ukraine Globally Harmonized System of classification of chemicals has not been implemented yet. In this article we analyze differences between GHS/CLP classification systems and Hygienic Classification of Pesticides by the Degree of Hazard currently in force in Ukraine in respect of approach and criteria for classification of effects on skin. As a case study, we conducted in silico modelling of herbicide imazamox using skin irritation/corrosion modules of ToxTree. The prediction of ToxTree was "Not Corrosive to skin". Then skin irritation and skin corrosion in vitro tests (OECD TGs 439, 431) were conducted. Classification of this substance based on in vitro and in vivo results according to GHS/CLP was the same, while it was not possible based on in vitro results to assign certain hazard class of Ukrainian classification due to difference in its and GHS/CLP criteria. However, ongoing process of harmonization of Ukrainian legislation with EU will give opportunity not only use alternative methods, but also adopt most recent advances and incorporate data from non-animal methods directly into classification criteria.

[EFFECT OF MANGANESE AND NICKEL ON PROLACTIN LEVELS IN WOMEN WITH POLYCYSTIC OVARY SYNDROME]

To study the relationship between the level of exposure to manganese and nickel and prolactin levels in the serum in women with рolycystic ovary syndrome (PCOS). 35 women with PCOS and 38 healthy women of reproductive age were examined. All women lived in Kiev. Manganese and nickel indices were determined in serum by the method of an іnductively coupled plasma mass spectrometry. The study of the ecological situation was carried out by analyzing open sources of information. Our study has shown that women with PCOS show an increase in manganese and nickel serum levels. Also significantly higher levels of prolactin was found. In the group of women with PCOS, elevated serum manganese concentrations correlated with an increase in prolactin levels (P=0.0134). There was no correlation between the levels of prolactin and the concentration of nickel in the serum of patients with PCOS. In healthy women, no correlation of prolactin and manganese or nickel levels was found. These results confirm the existing view that exposure to manganese may be the cause of increased levels of prolactin. Nickel exposure does not affect prolactin levels. Women with PCOS show an increase in prolactin levels, that depends on the level of exposure to manganese. This data suggest that an increased level of exposure with manganese can be attributed to factors or co-factors for the occurrence of PCOS. Nickel exposure does not affect prolactin levels.