Assessment of ecotoxicological hazard and risk of contamination of groundwater with different groups of pesticides

Assessment of ecotoxicological hazard and risk of contamination of groundwater with different groups of pesticides. Stavnichenko P.V., Novohatska L.O., Antonenko A.M., Vavrinevych O.P. The aim of our work was to determine ecotoxicological risk of herbicides, insecticides, fungicides of different chemical classes with different mechanisms of action by the method of Melnikov M.M. and leaching potential index by the method of Sergeev S.G. and co-workers. It was established that in soil and climatic conditions of Ukraine ecotoxicological hazard of studied herbicides by (1-6) orders of magnitude, fungicides – by (3-5) orders, insecticides – by (2-3) orders lower than DDT. The least ecotoxic are herbicides of the last generations, then fungicides and the most ecotoxic are insecticides and herbicides of the old first generations. It was proved the high danger of groundwater contamination with studied herbicides, insecticides and fungicides, except for mesotrione, the application of which has moderate danger in the soil and climatic conditions of Ukraine. It was shown that in soil and climatic conditions of Ukraine, ability of migration from the soil into groundwater of metribuzin, thiamethoxam, paclobutrazole is high, topramezone and mesotrione – moderate, for other substances – low; in terms of hygienic standards in the ground itallows to avoid them getting into the soil flow and minimize the danger of groundwater contamination to public health Реферат. Оцінка екотоксикологічної небезпечності та ризику забруднення підземних вод різними групами пестицидів. Ставніченко П.В., Новохацька Л.О., Антоненко А.М., Вавріневич О.П. Метою роботи була оцінка екотоксикологічної небезпечності гербіцидів, інсектицидів, фунгіцидів різних хімічних класів з різним механізмом дії за методом Мельникова М.М. та індексу вимивання в ґрунтові води за методом Сергєєва С.Г. та співавторів. Встановлено, що в ґрунтово-кліматичних умовах України екотоксикологічний ризик досліджуваних гербіцидів на (1-6) порядків, фунгіцидів – на (3-5) порядків, інсектицидів – на (2-3) порядків нижче, ніж ДДТ. Найменш екотоксичними є гербіциди останніх поколінь, за ними йдуть фунгіциди, а найбільш екотоксичні – інсектициди та гербіциди старих генерацій. Доведено високу небезпечність забруднення підземних вод у ґрунтово-кліматичних умовах України досліджуваними гербіцидами, інсектицидами та фунгіцидами, за винятком мезотріону, при застосуванні якого існує середня небезпечність. Показано, що в ґрунтово-кліматичних умовах України здатність міграції з ґрунту в підземні води метрибузину, тіаметоксаму, паклобутразолу – висока, топрамезону та мезотріону – середня, для решти речовин – низька, що за умови дотримання гігієнічного нормативу в ґрунті дозволяє уникнути їх потрапляння в ґрунтовий потік та мінімізувати небезпечність забруднення підземних вод для здоров’я населення. Introduction. Population growth, industrial development and intensification of agriculture in Ukraine led to increased pollution of the environment with ecotoxicants. Many toxic substances entering the atmosphere, soil and water sources cause a negative impact on autochthonous flora of surface water and soil, plants, animals and human [17]. Among these ecotoxic substances pesticides occupy a special place. First of all, because they are designed to killing and limitation of living organisms – weeds, pathogens of plants, insects and rodents. However, pesticides are potentially harmful both for many species of flora and fauna and for humans. ПРОФІЛАКТИЧНА МЕДИЦИНА МЕДИЧНІ ПЕРСПЕКТИВИ / MEDICNI PERSPEKTIVI 120 Therefore, assessment of environmental safety of pesticides and risk of their application is mandatory for their development and registration [10, 15]. Therefore, the aim of our study was to assess the ecotoxicological risk of herbicides, insecticides, fungicides of different chemical classes with different mechanisms of action. MATERIALS AND METHODS For the calculation of ecotoxicological risk, so-called ecotox, the method proposed by M.M. Melnikov was used for assessment of potential risk of fungicides, insecticides, herbicides application for ecosystems and biocenosis [11]. Mathematical modeling method that provides calculatied reproduction of process of pesticides destruction by actual data to predict their persistence was used for calculaion of half-life periods (DT50) of substances in the soil [13, 14]. For the prediction of groundwater pollution with studied pesticides, calculation of integrated vectors of hazard according to Sergeev S.G. et al. methodology was used [6]. The calculated indicator values expressed in points were used for calculation of integral vectors of groundwater contamination. RESULTS AND DISCUSSION As a result of field studies, we found that the concentration of the compounds in the soil and crops during the vegetation season was gradually decreasing and was not found at harvest. Based on the evidence on the dynamics of residual amounts of these substances in soil, the DT50 values were calculated. According to obtained data and to "Hygienic classification of pesticides and agrochemicals" State Standards 8.8.1.002-98 [16] herbicides isoxaflutole and mesotrione pertain to hazard class 4 (unstable); fungicides topramezone, fluxapyroxad, cyflufenamid, famoxadone, oxathiapiprolin and herbicide metribuzin – to class 3 (moderately stable); herbicide flufenacet and insecticides thiamethoxam, imidacloprid – to class 2 (stable) Other studied compounds class 1 (stable). We have calculated the ecotox values of studied substances in the agro-climatic conditions of Ukraine (table. 1). Their values range between 1,2010 and 2,7510 for herbicides; between 1,18×10 and 2,40×10 for fungicides and between 2,79×10 and 1,26×10 for insecticides. Thus, ecotoxicological hazard of studied herbicides by (1-6) orders of magnitude, fungicides – by (3-5) orders, insecticides – by (2-3) orders lower than DDT. It can also be concluded that the least ecotoxic are herbicides of the last generations, then – fungicides, and the most ecotoxic are insecticides and herbicides of the old first generations (table 1). Evaluation of hazard to the environment of test substances except for ecotoxicological hazard prediction, involves determining the potential risk of groundwater contamination in rural areas, which are widely used as a source of decentralized drinking water supply. The integrated vectors were calculated for the prediction of groundwater pollution with test groups of pesticides. Initial data and results of GUS and Z biol.ef. calculations are shown in table 2. The values of the indicators were expressed in points, and then integral vectors of hazard of groundwater contamination were calculated and evaluated according to a scale provided in [6]. The results are shown in table 3. The data in table 3 indicate a high danger of groundwater contamination in the soil and climatic conditions of Ukraine with studied herbicides, insecticides and fungicides. except for mesotrione, the application of which is of danger for secondary contamination of groundwater. There is a moderate hazard of groundwater contamination with mesotrione, which is an exception among all studied pesticides. The high danger of groundwater contamination with topramezone, isoxaflutole, famoxadone is determined mainly by their toxicity and cumulativeness in warm-blooded animals. Fluxapyroxad, oxathiapiprolin, imidacloprid, flufenacet, diquat have high hydrolytic stability, cyflufenamide, difenoconazole – have both characteristics. At the same time, all of these substances, except for metribuzin, thiamethoxam, paclobutrazole, have average or low ability to migrate from the soil into groundwater. In terms of observance of hygienic standards in the soil, this allows to avoid them from getting into the soil flow. In soil and climatic conditions of Ukraine according to GUS indeces hazard of the test substances migration from the soil into groundwater is: for metribuzin, thiamethoxam, paclobutrazole – high, topramezone and mesotrione – moderate, for the rest of substances – low. The above mentioned suggests necessity of considering migration process of metribuzin, thiamethoxam, paclobutrazole in the "soil-groundwater" system in justifying their hygiene standards in soil using calculation method.

Introduction.Population growth, industrial development and intensification of agriculture in Ukraine led to increased pollution of the environment with ecotoxicants.Many toxic substances entering the atmosphere, soil and water sources cause a negative impact on autochthonous flora of surface water and soil, plants, animals and human [17].
Among these ecotoxic substances pesticides occupy a special place.First of all, because they are designed to killing and limitation of living organisms -weeds, pathogens of plants, insects and rodents.However, pesticides are potentially harmful both for many species of flora and fauna and for humans.
Therefore, assessment of environmental safety of pesticides and risk of their application is mandatory for their development and registration [10,15].
Therefore, the aim of our study was to assess the ecotoxicological risk of herbicides, insecticides, fungicides of different chemical classes with different mechanisms of action.

MATERIALS AND METHODS
For the calculation of ecotoxicological risk, so-called ecotox, the method proposed by M.M. Melnikov was used for assessment of potential risk of fungicides, insecticides, herbicides application for ecosystems and biocenosis [11].
Mathematical modeling method that provides calculatied reproduction of process of pesticides destruction by actual data to predict their persistence was used for calculaion of half-life periods (DT 50 ) of substances in the soil [13,14].
For the prediction of groundwater pollution with studied pesticides, calculation of integrated vectors of hazard according to Sergeev S.G. et al. methodology was used [6].The calculated indicator values expressed in points were used for calculation of integral vectors of groundwater contamination.

RESULTS AND DISCUSSION
As a result of field studies, we found that the concentration of the compounds in the soil and crops during the vegetation season was gradually decreasing and was not found at harvest.Based on the evidence on the dynamics of residual amounts of these substances in soil, the DT 50 values were calculated.According to obtained data and to "Hygienic classification of pesticides and agrochemicals" State Standards 8.8.1.002-98[16] herbicides isoxaflutole and mesotrione pertain to hazard class 4 (unstable); fungicides topramezone, fluxapyroxad, cyflufenamid, famoxadone, oxathiapiprolin and herbicide metribuzin -to class 3 (moderately stable); herbicide flufenacet and insecticides thiamethoxam, imidacloprid -to class 2 (stable) Other studied compounds -class 1 (stable).
It can also be concluded that the least ecotoxic are herbicides of the last generations, then -fungicides, and the most ecotoxic are insecticides and herbicides of the old first generations (table 1).
Evaluation of hazard to the environment of test substances except for ecotoxicological hazard prediction, involves determining the potential risk of groundwater contamination in rural areas, which are widely used as a source of decentralized drinking water supply.
The integrated vectors were calculated for the prediction of groundwater pollution with test groups of pesticides.Initial data and results of GUS and Z biol.ef.calculations are shown in table 2.
The values of the indicators were expressed in points, and then integral vectors of hazard of groundwater contamination were calculated and evaluated according to a scale provided in [6].The results are shown in table 3.
The data in table 3 indicate a high danger of groundwater contamination in the soil and climatic conditions of Ukraine with studied herbicides, insecticides and fungicides.except for mesotrione, the application of which is of danger for secondary contamination of groundwater.There is a moderate hazard of groundwater contamination with mesotrione, which is an exception among all studied pesticides.
At the same time, all of these substances, except for metribuzin, thiamethoxam, paclobutrazole, have average or low ability to migrate from the soil into groundwater.In terms of observance of hygienic standards in the soil, this allows to avoid them from getting into the soil flow.
In soil and climatic conditions of Ukraine according to GUS indeces hazard of the test substances migration from the soil into groundwater is: for metribuzin, thiamethoxam, paclobutrazolehigh, topramezone and mesotrione -moderate, for the rest of substances -low.The above mentioned suggests necessity of considering migration process of metribuzin, thiamethoxam, paclobutrazole in the "soil-groundwater" system in justifying their hygiene standards in soil using calculation method.17/ Том XXІІ / 2   (1)(2)(3)(4)(5)(6) orders, fungicides -by (3-5) orders, insecticides -by (2-3) orders of magni-tude lower than DDT.The least ecotoxic are herbicides of the last generations, then -fungicides, and the most ecotoxic are insecticides and herbicides of old first generations.
2. It was proved a high danger of groundwater contamination with studied herbicides, insecticides and fungicides, except for mesotrione, the application of which has moderate danger in the soil and climatic conditions of Ukraine.
3. It was shown that in soil and climatic conditions of Ukraine ability of migration of metribuzin, thiamethoxam, paclobutrazole from the soil into groundwater is high, topramezone and mesotrionemoderate, of other substances -low, in terms of following of hygienic standards in the ground this allows to avoid them from getting into the soil and to minimize the danger to public health of groundwater contamination.

T a b l e 1
Comparative assessment of ecotoxicological hazard of different groups, classes and generations of pesticides Mode