O. Kravchuk, O. Bahatska, V. Medvediev, A. Hrynko, L. Ivanova, O. Kuznietsova, V. Lyshavskyi, S. Yushchuk, H. Petrashenko
State Enterprise “L. I. Medved’s Research Center of Preventive Toxicology, Food and Chemical Safety”, Ministry of Health of Ukraine, Kyiv
ABSTRACT. Objectives. THygienic evaluation of residual spirodiclofen and regulation of the use of spirodiclofen-based product Envidor SC 240 for fruit and vegetable crops in the agro-industrial sector and private households of Ukraine.
Methods. Study of changes in residual spirodiclofen in apples, pears, grapes, cucumbers and eggplants overtime was performed in different agroclimatic zones of Ukraine during field experiments. Consumption rates of spirodiclofen were 120 g/ha as two applications, and 144 g/ha as 3 applications in the agro-industrial sector, and 1.2 g/0.01 g as two applications at private households. Residual spirodiclofen in the test samples of agricultural products was measured using chemical analytical methods of high-performance liquid chromatography (HPLC).
Results. Results of conducted studies suggest a moderate reduction in the residual amounts of the active ingredient in fruit crops and the rapid one in vegetable crops. It was found that during harvesting, spirodiclofen content in apples and pears did not exceed MAL (maximum allowable limit); spirodiclofen was not detectable in grapes, eggplants and cucumbers. Calculation of half-lives of the test substance in the treated plants during vegetation was performed. Theoretically, the possible intake of spirodiclofen in an adult and a child under the age of 6 years with fruit, vegetable crops, and grapes was calculated. The obtained data were evaluated by the level of acceptable daily intake (ADI) of the substance in the human body.
Conclusion. As per limiting toxicity parameters under conditions of the acute experiment, spirodiclofen and spirodiclofen-based product belong to hazard class 2 pesticides. By a degradation value in plants, spirodiclofen belongs to hazard class 1–4 pesticides. Approved MALs of safe content of the substance under experiment in fruit and vegetable crops, grapes and safety interval before harvesting provide for safe use of spirodiclofen-based insecticide-acaricide.
Key Words: spirodiclofen, residual amounts of pesticides, field experiments.
Plant-feeder mites are one of the most dangerous pests of fruit, berry and vegetable crops. The presence of large areas of fruit plantations, vineyards and vegetables in the agro-industrial sector (AIS) and private households (PHHs) and the increasing demands on their productivity and quality of production make the problem of protection against mites quite relevant. The diverse species composition of harmful mites, their ability to quickly propagate during the season and adapt to traditional drugs require the use of new plant protection products (PPPs). Spirodiclofen-based insecticide-acaricides have proven themselves effective in addressing this problem. The innovative active ingredient spirodiclofen belongs to a new chemical class — ketoenols (tetronic acids). The substance confidently controls virtually all species of harmful mites on perennial crops, in addition, it is effective on cereals against some sucking insects of pear louse (Psylla piri), mussel scale ( Lepidosaphes ulmi) and some species of frog-flies [1].
Since spirodiclofen is highly effective from the beginning to the end of the growing season of crops and can be used at the final stages of fruit and vegetable formation, it is necessary to study residues of this active ingredient in agricultural products and to evaluate the safety of the use of spirodiclofen-based products for health. Thus, the objective of this paper is a hygienic evaluation of residual spirodiclofen and regulation of the use of spirodiclofen-based product Envidor SC 240 for fruit and vegetable crops in the agro-industrial sector and private households of Ukraine.
Materials and methods. Study of changes in residual spirodiclofen in apples, pears, grapes, cucumbers and eggplants overtime was performed during state tests Envidor SC 240 of in different agroclimatic zones of Ukraine under conditions of agro-industrial manufacture and private households. The studies were conducted in accordance with the principles set out in international and national documents [2, 3].
Consumption rates of spirodiclofen were 120 g/ha as 2 applications in the agro-industrial sector, and 1.2 g/0.01 ha as 2 applications at private households. For each crop, 5–6 post-treatment sampling points were included, including the market maturity phase. Sampling and transportation of samples of the study objects were carried out in accordance with the uniform sampling rules [4].
Organoleptic studies of the selected samples revealed no change in appearance, odour, and taste compared to controls.
The chemical and analytical determination of spirodiclofen was carried out in accordance with guidelines for determination of the active ingredient in the corresponding matrices developed by ECOGINTOX [5-7]. The limit of quantification of spirodiclofen by high-performance liquid chromatography (HPLC) in eggplants, cucumbers, apples, pears, grapes and their products (juices) is 0.02 mg/kg.
Results and their discussion. Spirodiclofen, according to the Hygienic classification of pesticides by hazard degree (DSanPiN 8.8.1.002-98) [8], according to acute oral and dermal toxicity belongs to hazard class 4, according to inhalation toxicity — to hazard class 3, according to irritation of skin and eye mucous membranes — to hazard class 4, and by allergenic action — to hazard class 2.
According to its mutagenicity, spirodiclofen belongs to hazard class 4, carcinogenicity — to hazard class 2, teratogenicity and embryo- and reproductive toxicity — to hazard class 3.
As per limiting toxicity criteria, spirodiclofen belongs to hazard class 2
Envidor 240 SC by its limiting toxicity criteria (inhalation toxicity and sensitization) belongs to hazard class 2.
In Ukraine, approved ADI of spirodiclofen for a human is 0.001 mg/kg.
Behaviour parameters of spirodiclofen in environmental objects, according to the U.S. Environmental Protection Agency, European Food Safety Authority (EFSA) and other sources [9-13] are provided in Table 1.
Table 1
Behaviour of spirodiclofen in environmental objects
According to the provided data, spirodiclofen (according to DSanPiN 8.8.1-002-98) by the parameter “stability in soil” can be classified as hazard class 3–4 pesticides (moderate and low-resistance), by the parameter “stability in water” — hazard class 2 pesticide (resistant). The substance is not mobile in soil, groundwater contamination is not expected.
According to the results of studies conducted by ECOGINTOX during field tests, it was established that the half-life of spirodiclofen in soil in the conditions of Ukraine is 2 days, which makes it possible to classify it as hazard class 4 by the parameter “stability in soil” (statistical parameters of spirodiclofen destruction in soil are provided in Table 4).
Considering the potential and real danger of spirodiclofen-based preparations and the wide range of fruit and vegetable crops on which they are used, in order to assess the danger of agricultural products, literature data on the content of residual spirodiclofen content in crops were analysed, and investigation of changes in the content of active ingredient in pears, grapes, cucumbers and eggplants over time after application of Envidor 240 SC in the field conditions was performed.
According to the literature, the destruction of spirodiclofen in fruit crops occurs by cleavage of ether bonds and hydrolysis. The rate of degradation is rather low and occurs mainly on the surface of the fruit. The main significant component of residues is spirodiclofen (34–89 % of initial concentration after last treatment for early use and 75–99 % for late use). The identified metabolites (about 11) are measured in a small amount (3.5 %) and are characterized by toxicological criteria as corresponding to the parent molecule. Therefore, residual controls for risk assessment and monitoring have been proposed for spirodiclofen [9-11].
The results of studies of the changes in the content of spirodiclofen in apples, pears, grapes and cucumbers over time, obtained in Germany, Belgium, Great Britain, France, Spain, Italy, USA, Canada and Brazil [10], are provided in Table 2.
Table 2
Spirodiclofen residues in apples, pears, grapes and cucumbers according to field studies in EU, US, Canada and Brazil
Based on studies conducted for spirodiclofen in the European Union and the US, maximum residues levels (MRLs) have been established [14], and they are presented in Table 3.
Table 3
MRLs of spirodiclofen in apples, pears, cucumbers, grapes and eggplants
During field studies in Ukraine, it was found that the content of spirodiclofen in apples of the Mutsu + Montian variety mixture and pears of Mramorna variety grown in the agricultural sector in the Region of Cherkasy gradually decreased from 0.06 mg/kg and 0.065 mg/kg at the day of treatment up to 0.02 mg/kg and 0.015 mg/kg during harvesting period (day 42 and day 30 after the last treatment), respectively. In apples of Aidared variety and pears of Zymova Mliivska variety, spirodiclofen was not detected at the level of the limit of detection by HPLC method — 0.0007 mg/kg at day 41 (harvesting period).
The number of spirodiclofen in apples and pears, which were treated in private households of the Region of Kyiv, was 0.26 mg/kg and 0.06 mg/kg at the day of treatment, respectively, and gradually decreased. During the harvesting period (day 57 and day 48), spirodiclofen was not detected in apples at the level of the limit of detection by HPLC — 0.0007 mg/kg, and its content in pears was 0.02 mg/kg.
A similar pattern was observed for grapes grown in the Region of Bakhchisarai of the Crimea. For example, the content of spirodiclofen in grape berries decreased from 0.71 mg/kg at the day of treatment to 0.23 mg/kg at day 20 after treatment. During the harvesting period (day 57), the active ingredient in grape berries and the juice obtained from them was not found at the level of the limit of detection by HPLC — 0.0007 mg/kg.
In green cucumber plants at the day of treatment, the content of spirodiclofen was 1.6 mg/kg. In cucumbers at all study points (day 0, 7, 14, 20, 30), spirodiclofen was not detected at the level of the limit of detection by HPLC — 0.0007 mg/kg.
In greens of eggplants at the day of treatment spirodiclofen was found at the level of 1.01 mg/kg. In eggplants, the number of spirodiclofen gradually decreased from 0.37 mg/kg at day 7 after treatment to 0.05 mg/kg at day 20. During the harvesting period (day 30), spirodiclofen in eggplants was not detected at the level of the limit of detection by HPLC — 0.0007 mg/kg.
The results of studies of changes in decomposition of spirodiclofen in apples, pears, grapes and eggplants over time have shown that the decrease of its content in the studied cultures occurs according to the exponential curve (Fig. 1).
Fig. 1. Changes in decomposition of spirodiclofen in fruit and vegetable crops, grown in the agro-industrial sector (B) and in apples and pears, grown in private households (A).
Using the data obtained from field studies and first-order equations [15–17], the decomposition rate constant (k) and half-life (T 50) of spirodiclofen for apples, pears, grapes, eggplants and soil were calculated (Table 4).
Table 4
Decomposition rate and hazard class
The results provided in Table 4, show that the values of the coefficient of determination of R2 are quite high (over 0.8), which indicates a significant dependence between the variables selected and the reliability of the model used [15].
The calculated half-lives are as follows: for apples — 6.5–28 days, pears — 15–35 days, grapes — 7 days, eggplant — 5 days. The obtained data allow in accordance with Hygienic classification of pesticides by hazard degree (DSanPiN 8.8.1.002-98) classifying spirodiclofen according to the parameter “resistance in vegetative crops” in pears as hazard class 1–2, in apples — as hazard class 2–3, in grapes — as hazard class 3, in eggplants and cucumbers — as hazard class 4.
Spirodiclofen was not found in apple, pear and grape juices obtained from apples, pears and grape berries. According to the literature [9–10], the effect of technological processing on the level of spirodiclofen in the products of apple and grape processing has been studied. The value of the processing coefficient is provided in Table 5.
Table 5
The coefficient of technological processing of spirodiclofen in the products obtained from apples and grapes
Based on the data in Table 5, it can be argued that spirodiclofen in juice, apple puree and dried fruits in the case of technological processing of fruits and berries will not be concentrated, since the processing coefficient is much lower than 1.0. Concentration is only possible in oil cake of apple and raisins, technological processing coefficient for which is much higher than 1.0 [18]. In the EU, a maximum allowable level of spirodiclofen residues of 4.0 mg/kg and 0.3 mg/kg, respectively, is recommended for these products.
Thus, the presence of spirodiclofen in juices is not predicted, which is confirmed by the results of our studies.
For the safe consumption of agricultural products, the maximum allowable levels (MALs) of residual spirodiclofen and safety interval before harvesting have been justified. Table 6 provides the set hygienic standards and regulations.
Table 6
Maximum allowable levels and safe intervals before harvesting
Vegetables and fruits have a significant share in the diet of employable population and children, therefore, possible intake of spirodiclofen in the body of adults and children aged from 6 years from the above products was calculated.
Its safe content was determined based on the daily consumption of these products and the acceptable daily intake (ADI) of spirodiclofen, which is scientifically justified at the level of 0.001 mg/kg. The acceptable daily intake (ADI) of spirodiclofen to the human body with an average body weight of 60 kg is 0.06 mg, a child aged 6 years with an average body weight of 20 kg — 0.02 mg.
According to the principles of complex pesticide rationing, the highest amount of spirodiclofen that can penetrate the human body during the day is 70 % of ADI, i.e 0.042 mg for an adult and 0.014 mg for a 6-year-old child.
These data suggest that the intake of spirodiclofen at the level of the recommended standard (MAL) in the body of an adult with fruit and vegetable crops is 0,012 mg, not exceeding 20.2 % of ADI; and in the body of a child aged 6 years — 0.006 mg, which does not exceed 30.6 % of ADI (Fig. 2).
Fig. 2 . Acceptable daily intake of spirodiclofen in the body of a child aged 6 years (A) and employable population (B).
Conclusion
1. According to Hygienic classification of pesticides by hazard degree (DSanPiN 8.8.1.002-98), spirodiclofen and spirodiclofen-based product Envidor 240 SC by limiting toxicity parameters belong to hazard class 2.
2. The content of spirodiclofen in apples, pears during the harvesting period did not exceed 0.02 mg/kg, and active ingredient was not detected in grapes, grape, apple and pear juices, cucumbers and eggplants.
3. Constants of decomposition rate and half-lives of spirodiclofen calculated by the results of field studies, allow to classify the active ingredient by the “parameter stability in vegetative crops” in pears as hazard class 1–2, in apples — as hazard class 2–3, in grapes — as hazard class 3, in eggplants and cucumbers — as hazard class 4.
3. The maximum allowable levels of spirodiclofen content in apples, pears, grapes and their juices, eggplants and cucumbers are justified at 0.02 mg/kg (limit of quantification by HPLC is 0.02 mg/kg).
4. The possible daily intake of spirodiclofen with fruit and vegetable crops for adults and children aged 6 years is 20.2 % and 30.6 % of the acceptable daily intake, respectively.
5. When hygienic regulations for the use of the insecticide-acaricide Envidor 240 SC based on spirodiclofen in the agro-industrial sector and private households for the protection of fruit and vegetables are followed, it will not cause contamination of the fruit, berries and vegetables beyond the established hygienic rates for human health.
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