P. Stavnichenko¹, А. Antonenko¹, М. Korshun², S. Omelchuk³, V. Bardov O.O.¹

Bogomolets National Medical University
¹ Hygiene and Ecology Department № 1,
² Hygiene and Ecology Department № 3,
³ Hygiene and Ecology Institute Kyiv, Ukraine

SUMMARY. Annually more than 2 million tons of chemical plant protection products are introduced into the fields of the planet due to the need to preserve the crop. However, with multiple introduction of persistent pesticides, soil can become a source of pollution of crop production.

The Purpose of our work was to predict the danger for children of all ages when consuming agricultural products contaminated with fungicides of the amides and triazoles classes.

Materials and Methods. For an integrated assessment of the potential hazard on a four-graded scale, the allowable daily intake, the half-life in plants, and the average daily consumption of the product were estimated. When estimating the average daily consumption of products for children under the age of 18, the safety coefficients were used.

Results. According to the persistence in agricultural cultures, fungicides cyflufenamide and difenoconazole were classified as hazard classes 3 (moderately stable). By the integral indicator of the danger when consuming pesticide-contaminated products for adults, difenoconazole is very dangerous (grade 4), cyflufenamide —moderately dangerous (grade 3).

Conclusion. It has been established that for children, depending on their age, both studied active substances can be from extremely dangerous for infants and children of preschool age to a low or moderately dangerous for adolescents.

Key Words: risk, pesticides, food products, children.

Every year, over 2 million tons of agricultural chemicals are used in the fields of our planet. The circulation of pesticides in soil, water and atmospheric air leads to contamination of the biosphere and deterioration of its quality [1]. Excessive use of pesticides coupled with industrial contamination further complicates the ecological situation in Ukraine and reduces the restorative capacity of the biosphere and ecological resilience of cultivated lands [3].

The use of pesticides is driven by the need to preserve the crop of agricultural plants, this is why they are introduced into farming ecosystems; in this way, pesticides are continuously circulating in the environment. Multiple uses of persistent pesticides may make the soil a source of contamination for agricultural plants [2, 3]. 

Assessment of the risks associated with the consumption of foods containing residual pesticides is a vitally important and integral part of the regulatory process [4].

The aim of our work included prediction and comparative assessment of the hazards associated with the consumption of agricultural produce contaminated with amide and triazole fungicides in children and adolescents of various age groups.

Materials and methods of the study. For the purposes of this study, the author has selected modern fungicides belonging to promising chemical classes of amides (сyflufenamid) and triazoles (difenoconazole).

The parameters of the persistence of investigational fungicides in agricultural crops under the edaphoclimatic conditions of Ukraine are given based on the findings of the author’s own field study.

Information on physicochemical properties as well as basic toxicological information is provided according to literature data [5].

During assessment of the behaviour of investigational fungicides in agricultural crops, in order to calculate half-lives (τ₅₀) and time to almost complete disintegration (τ₉₅) of investigational substances in herbage of the plants, the author has used a mathematical modelling method, which involved calculational simulation of pesticide disintegration based on actual data, which allows predicting the persistence of pesticides [6, 7, 8, 9].

In order to perform an integral assessment of potential hazards related to the human effects of pesticides in the consumption of contaminated agricultural produce, the author has used a four-grade scale to assess allowable daily dose (ADD), half-life (τ₅₀) in plants and mean daily consumption of the product (see Table 1) [10].

During the assessment of mean daily consumption of products in children up to 18 years of age, the author has used a margin of safety (MoS), which was calculated by dividing mean body weight of an adult (non-occupational populations) [60 kg] (М) by mean body weight of a child of a particular age (m): MoS = M/m.

Therefore, the margin of safety for children younger than 1 year of age is 6.0 (for children 1 to 5 years of age = 3.0; for children 6 to 10 years of age: 2.0; for children 11 to 14 years of age = 1.5 and for children 15 to 18 years of age = 1.2).

If the investigational pesticide is used on different agricultural produce, the values of respective mean daily consumptions are added and total mean daily consumption is assessed on a point-based scale.

After adding all the points obtained, the integral hazard index in products consumption (IHIPC) is graded in the following manner: IHIPC of 3–5 points —substances with low hazard for humans (Class 4), 6–8 points — moderately hazardous (Class 3), 9–11 points — hazardous (Class 2), >11 points — extremely hazardous (Class 1) substances.

Table 1

Grading scale of pesticide hazard indices in use of contaminated foods

Notes: 1. – If the product is used raw or as baby food, the half-life is increased two-fold for the purposes of scoring; 2. – An additional margin of safety (MoS) is used in children younger than 18 years of age.

Results and discussion. A field study in different edaphoclimatic zones of Ukraine and the use of mathematical modelling method allowed calculating the parameters of the persistence of investigational substances in vegetating agricultural crops (τ₅₀) (see Table 2).

Mathematical processing of the results obtained in a field experiment to assess how residual amounts of amide and triazole fungicides changed with time has shown that under edaphoclimatic conditions of Ukraine the process of disintegration of these substances in agricultural crops was exponential in nature.

Statistical processing of disintegration rates of investigational amides and triazoles (see Table 2) in agricultural crops has shown that any variances in values of k, τ₅₀ and τ₉₅ in different fruit and vegetable crops were not significant for either сyflufenamid or difenoconazole (р > 0.05). This enabled the authors to calculate averaged values of k, τ₅₀ and τ₉₅ for the aforesaid fungicides in plants.

Table 2

Disintegration rates of investigational fungicides in objects of farming ecosystems

In terms of persistence in agricultural crops, such fungicides as сyflufenamid and difenoconazole may be classified as Class 3 hazardous substances (moderately persistent).

However, half-lives only reflect how long a pesticide persists in agricultural crops and, respectively, the risk that it gets into a human body. This does not make it possible to assess the human health risks of consuming contaminated produce.

Taking into account that investigational agricultural crops can be a part of baby food products, it is very important to perform a risk assessment of using such products by children of various age groups taking into account the peculiarities of nutrition and the increased susceptibility of children.

Calculations performed with the proposed method have shown that for adults difenoconazole was a low-hazard substance (Class 4) and сyflufenamid was a moderately hazardous substance (Class 3). However, the younger the child, the more dangerous consumption of pesticide-contaminated foods becomes (see Table 3).

This is primarily related to the fact that these are low-hazard substances from the toxicological perspective (i.e. with quite high ADDs) and also to the fact that these substances are rapidly destroyed in agricultural produce.

Table 3

Hazard indices of pesticides in consumption of contaminated products (for adults)

Notes: 1 = the value of the parameter/index; 2 = the class according to proposed method.

Conclusions

1. It has been shown that under edaphoclimatic conditions of Ukraine, сyflufenamid and difenoconazole may be classified as Class 3 hazardous substances (moderately persistent) in terms of their persistence in agricultural crops.
2. In terms of integral hazard index in consumption of pesticide-contaminated products (IHIPC) for adults, the triazole investigational compound (difenoconazole) belongs to hazard class 4 (low hazard), the amide compound (сyflufenamid) is moderately hazardous (Class 3). In children, depending on their age, the hazard of both investigational active compounds may be from “extremely hazardous” in infants and preschoolers to “low-hazard” or “moderately hazardous” in adolescents.

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Надійшла до редакції: 8.06.2018 р.