3.2. Detection of Nine Pesticide Pesticides in Grape Specimens
Among the 86 analysed samples, pesticides were detected in 80 (93.0%), all above the LOQ residues. Contamination percentages, concentration range, and prevalence of pesticides are outlined in Table 3. The most detected pesticides were Dimethomorph, followed by Pyrimethanil, Difenoconazole, Carbendazim, Prochloraz, Procymidone, Thiophanate, Metalaxyl, and Triadimefon. Dimethomorph was detected in 65 (75.6%) of the samples and occurred in 0.007 to 4.27 mg/kg. In China, Dimethomorph is a common pesticide contained in many registered mixed preparations. (Yang et al. 2020). Pyrimethanil was found in 56 (65.1%) samples at levels from 0.003 to 8.7 mg/kg. Difenoconazole was found in 50 (58.1%) samples at levels from 0.001 to 0.890 mg/kg.
Table 3
The pesticide residues detected in the grape samples.
Pesticide | Mean a (mg/kg) | Median a (mg/kg) | Minimum (mg/kg) | Maximum (mg/kg) | Detected Samples | MRLs (mg/kg) | Violative Compound | Violative Samples |
n | % | n | % | n | % |
Carbendazim | 0.053 | 0.027 | 0.013 | 0.156 | 26 | 30.2 | 3 | — | — | 6 | 6.98 |
Pyrimethanil | 0.471 | 0.091 | 0.003 | 8.70 | 56 | 65.1 | 4 | 1 | 1.16 |
Metalaxyl | 0.359 | 0.226 | 0.092 | 0.729 | 5 | 5.81 | 1 | — | — |
Dimethomorph (Z + E isomers) | 0.524 | 0.142 | 0.007 | 4.27 | 65 | 75.6 | 5 | — | — |
Prochloraz | 0.710 | 0.218 | 0.015 | 3.30 | 12 | 14.0 | 2 | 1 | 1.16 |
Difenoconazole | 0.134 | 0.027 | 0.001 | 0.890 | 50 | 58.1 | 0.5 | 4 | 4.7 |
ThiophanateMethyl | 0.283 | 0.099 | 0.005 | 1.18 | 8 | 9.30 | 3 | — | — |
Triadimefon | 0.005 | 0.005 | 0.005 | 0.005 | 1 | 1.16 | 0.3 | — | — |
Procymidone | 0.225 | 0.150 | 0.010 | 1.09 | 12 | 14.0 | 5 | — | — |
a Mean of samples where residues were detected. MRL: Maximum Residue Limit was obtained from GB 2763 − 2019, China. |
The research on pesticide residues in grapes from other groups had similar detection rates to this article. In one recent study (Si et al. 2021), the percentage of positive samples in grapes from farms of Shanghai of China was 97.5% (only one grape sample without any pesticide residues in 40 samples). While in another Chinese study was 100% (Zhang et al. 2021). Dibenzotriazole was the most identified pesticide in grapes, with the ranging from 0.011 to 0.408 mg/kg. Another study (Bouagga et al. 2019) also showed that all samples contained multiple residues in 64 grapes in Tunisia from 2015 to 2017. Among them, the detection rates of Carbendazim and Thiophanate Methyl were more than 50%. In the 2019 European Union report on pesticide residues in food (Authority E. F. S. et al. 2021), the number of grape samples without quantified residues was 377, while the number of grape samples with one or more residues was 1516. The calculated detection rate was 80.08%. One previous study (Bakirci et al. 2014) of pesticides in fruits from the Aegean region of Turkey showed that the detection rate of grape was 83%, while the most detected pesticide mentioned in this article in grapes was Pyrimethanil (19 of 83 samples), followed by Metalxyl (10 of 83 samples), then Dimethomorph and Carbendazim (both 9 of 83 samples). In Egypt, the detection rate of multi-class pesticides was 81.25% of the green grapes selected from the local market in 2011 (Eissa et al. 2013). The detection rates of the pesticides studied related this article were Carbendazim (40.63%), Difenoconazole (3.13%), and Metalaxyl (9.37%). In research from Slovenia (Baša-Česnik et al. 2008), the overall detection rate of pesticide residues was 97.9%, only one grape in 47 wine grape samples (2.1%) contained no residues. The pesticides related to our article were Metalaxyl (0.05–0.18 mg/kg) and Pyrimethanil (0.01–0.53 mg/kg), and the detection rates were 10.6% and 14.9%, respectively. However, the detection rates of pesticide residues in grapes in some other studies were lower than our experimental results. In a recent study, the percentage of positive samples in grapes from the mid-western region of China was 70.00% (Qin et al. 2021). Among them, the detection rates of the pesticides studied related to this article were Carbendazim (22.31%, ND-0.90 mg/kg), Difenoconazole (16.15%, ND-0.12 mg/kg), and thiophanate methyl (10.77%, ND-0.11 mg/kg). It can be concluded from the above that the detection rates of pesticide residues in grapes was very high. Liu et al. (2016) investigated the residues of nine pesticides in seven kinds of fruits including grapes and apples in Hangzhou of China from 2015 (Liu et al. 2016). The occurrence of pesticides in grapes was 56% (9 of 16 samples). Carbendazim was one of the most easily detectable residues in fruits, with a concentration range of 0.023–0.341 mg/kg. The comparison with the published research shows that the proportion of positive samples in grapes is usually very high, but the contamination level is variable and heterogeneous.
Our pesticide residues detection concentration was basically consistent with other reports, but the detection rates of several pesticides were much higher than other reports, including Dimethomorph, Pyrimethanil, and Difenoconazole. At present, in Shandong, there are two cultivation modes of grapes: greenhouse and open-air. The grapes cultivated in greenhouses are in an enclosed state during the flowering and young fruit period, and the low temperature and high humidity environment makes the occurrence of gray mould relatively heavy. The open-air cultivated grapes ripen during the rainy season in Shandong, (Shandong’s rainy season is July–September every year, which also happens to be the picking period of most of our grape samples), the high temperature and high humidity environment leads to the occurrence of downy mildew and other serious diseases. The picked grapes often rot due to gray mould during storage, transportation, and sales, which means that in different periods of grape growth, farmers use different pesticides. China implements a strict registration management system for pesticides. Through the search statistics of the pesticide registration data of China Pesticide Information Network, as of 7 January 2022, there were a total of 815 pesticide products registered in grape production in China, including 667 pesticides. There were 366 single agents and 301 mixtures of pesticides registered on grapes. The largest single-agent registrations was Dimethomorph with 48 registered products. Other pesticides registered on grapes related to our research were: eight Difenoconazole, twelve Procymidone, three Prochloraz, three Pyrimethanil, and two Thiophanate Methyl. Among them, the number of registered products of Dimethomorph accounted for the largest proportion of single doses of registered pesticide on grapes at 13.11%. There were 301 kinds of registered mixtures, 42 kinds of mixtures containing Dimethomorph, 45 kinds of Carbendazim, 24 kinds of Difenoconazole, and three kinds of Pyrimethanil. These data are consistent with the higher detection rates of pesticides including Dimethomorph and Difenoconazole in our research. As mentioned above, the common diseases of grapes are downy mildew, gray mold, and powdery mildew.
The above results were evaluated in accordance with the MRLs established by Chinese laws and regulations. Despite the high number of exposures, only six (6.98%) of the grape specimens contained pesticides above the MRLs. Among them, the concentration of Difenoconazole in four samples was 0.660–0.890 mg/kg, the concentration of Prochloraz in one sample was 3.30 mg/kg, and the concentration of Pyrimethanil in one sample was 8.70 mg/kg. These findings are very comparable to those of other studies. In a study of fruits’ pesticide residues from Turkey, 7.5% of grapes (55/728) showed multiple pesticide residues were higher than the values set by Turkish authorities (Soydan et al. 2021). While in the 2019 European Union report (Authority E. F. S. 2021), 28 of 291 grapes (9.6%) exceeded the MRLs. In Algeria, 12.5% samples with residues exceeding MRLs, which was higher than our research (Mebdoua et al. 2017). However, in some studies, the ratio of pesticide residues exceeding MRLs was much larger than that in our research. An investigation from Tunisia (Bouagga et al. 2019) found that at least one pesticide in 94% of grape samples exceeded the European MRLs. However, there were also situations that were contrary to our conclusion. For example, in the above mentioned study on pesticide residues in fruits in Shanghai, China (Si et al. 2021), although the detection rate of pesticide residues in grapes was 97.5%. According to GB2763-2019, the concentrations of all pesticides measured did not exceed the Chinese MRLs.
Figure 1 illustrates a range of pesticide residues. More than one pesticide contamination was found in 65 (75.6 percent) of these samples. Among them, a total of 15 (17.4%) samples of grapes that were examined contained two residues of pesticides, 25 (29.1%) samples were examined contained with three pesticide residues, and 25 (29.1%) samples were examined contained 4 or more pesticide residues. The number with the highest proportion of multiple pesticide residues was 3 residues, of which the most common combinations of pesticide residues were Dimethomorph, Pyrimethanil, and Difenoconazole. The sample with the most pesticides discovered has seven, which was proposed in Baša-Česnik et al. (2008). In Turkey, 42% of the positive fruit samples contained 2 or more residues, and grape was the fruit with the maximum number of residues. The results from Algria showed the majority of the analysed grape samples (57.5%) contained at least one pesticide, 25.0% were positive for one, 23.1% for two, 7.5% for three, and 1.9% for four or more pesticide residues (Mebdoua et al. 2017). Pesticide residues of more than one pesticide were identified in 49 percent of all recorded grapes during the period 2004–2011, according to the Danish monitoring program (Poulsen et al. 2017). According to Hjorth et al. (2011)., 71% of positive fruit and vegetable samples had more than one pesticide residue, with 13% of samples containing five or more pesticide residues (Hjorth et al. 2011). Two edible grape samples, both of which had nine pesticide residues, had the highest pesticide residues. The result was consistent with the findings of Bakirci et al. (2014) that grapes tend to contain four or more types of pesticide residues at the same time. The grapes are usually sprayed with pesticides every 7–10 days after the grapes have grown. Grape growers usually use a mixed pesticide formula because it can more effectively control a series of fungal diseases (Yang et al. 2020). However, if pesticides are mixed randomly, it will not only cause food safety hazards but can also easily lead to phytotoxicity. Excessive and frequent use of pesticides and random mixing should be avoided, and scientific and reasonable grape disease prevention and control technology should be established.
3.3. Health Risk Assessment
Pesticide levels in grapes (mg/kg day) were derived from consumption data, weight per capita, and our monitoring data (maximum residue and mean residue). Three scenarios were used for the chronic risk assessment in the report (Authority E. F. S. et al. 2021), including the lower, the middle and the upper bound scenario. In the upper and lower bound (UB and LB) scenarios, the unquantified results were replaced by 0 or value of LOQ. In addition, the middle bound (MB) scenario was calculated by assigning LOQ/2 to the result of the left truncation (Golge et al. 2018). The HQ of dietary risks from grapes contaminated with pesticides for adults and children is shown in Table 4.
Table 4
The short-term and long-term risks due to average daily intake of pesticides through grapes consumption in China.
Pesticide | Short-Term Risk | Long-Term Risk |
Maximum Residue (mg/kg) | ESTI | ARfD (mg/kg bw/day) | aHQ | Mean Residue (mg/kg) | EDI | ADI (mg /kg bw/ day) | cHQ |
Adults (mg/kg day) | Children (mg/kg day) | Adult (%) | Children (%) | | Children (mg/kg day) | Adults (%) | Children (%) |
Carbendazim | 0.156 | 8.73×10− 5 | 1.51×10− 4 | 0.1 | 8.73×10− 2 | 1.51×10− 1 | 0.053 | 2.97×10− 5 | 5.14×10− 5 | 0.03 | 9.89×10− 2 | 1.71×10 − 1 |
Pyrimethanil | 8.7 | 4.87×10− 3 | 8.43×10− 3 | / | / | / | 0.471 | 2.64×10− 4 | 4.57×10− 4 | 0.2 | 1.32×10− 1 | 2.28×10 − 1 |
Metalaxyl | 0.729 | 4.08×10− 4 | 7.07×10 − 4 | / | / | / | 0.359 | 2.01×10− 4 | 3.48×10− 4 | 0.08 | 2.51×10− 1 | 4.35×10 − 1 |
Dimethomorph(Z + E isomers) | 4.27 | 2.39×10− 3 | 4.14×10− 3 | 0.6 | 3.98×10− 1 | 6.90×10− 1 | 0.524 | 2.93×10− 4 | 5.08×10− 4 | 0.2 | 1.47×10− 1 | 2.54×10− 1 |
Prochloraz | 3.3 | 1.85× 10− 3 | 3.20×10− 3 | 0.1 | 1.85 | 3.20 | 0.71 | 3.97×10− 4 | 6.88×10− 4 | 0.01 | 3.97 | 6.88 |
Difenoconazole | 0.89 | 4.98× 10− 4 | 8.63×10− 4 | 0.3 | 1.66×10− 1 | 2.88×10− 1 | 0.134 | 7.50×10− 5 | 1.30×10− 4 | 0.01 | 7.50×10− 1 | 1.30 |
ThiophanateMethyl | 1.18 | 6.60× 10− 4 | 1.14×10− 3 | / | / | / | 0.283 | 1.58×10− 4 | 2.74×10− 4 | 0.09 | 1.76×10− 1 | 3.05×10− 1 |
Triadimefone | 0.005 | 2.80× 10− 6 | 4.85×10− 6 | / | / | / | 0.005 | 2.80×10− 6 | 4.85×10− 6 | 0.03 | 9.33×10− 3 | 1.62×10− 2 |
Procymidone | 1.09 | 6.10× 10− 4 | 1.06×10− 3 | 0.1 | 6.10×10− 1 | 1.06 | 0.225 | 1.26×10− 4 | 2.18×10− 4 | 0.1 | 1.26×10− 1 | 2.18×10− 1 |
ARfD and ADI were adopted from JMPR database and GB 2763 − 2019, China. The "/" indicated that no allowed value. The grape consumption value was calculated using the daily fruit intake recommendations of 38.17 g/day for adults and 42.18 g/day for children. (data from Survey on the total diet and health status of residents in Shandong Province, 2014). |
All aHQs were below 10%, in which the adults’ value ranged from 0.0873% for Carbendazim to 1.85% for Prochloraz, while the children’s aHQs ranged from 0.151% for Carbendazim to 3.20% for Prochloraz. This means that the short-term risks with the consumption of the tested pesticides via grape consumption were low. The highest adult aHQ value was 1.85% and the highest children aHQ value was 3.20% from Prochloraz, followed by 1.06% from Procymidone. A study from China also found that the aHQ value of prochloraz from fruits was 3.2533%, which was basically consistent with our results (Liu et al. 2016). Among the 104 pesticides they studied, only Bifenthrin presented a health risk to children. However, in the research of pesticide residues in grapes from Tunisia (Bouagga et al. 2019), the acute exposure values for adults and children were 0.52–1016% and 1.10–2100% of ARfD, respectively. Their results indicated that consumers in Tunisia may face serious health risks.
For chronic risk assessment, the cHQ values were also all below 10%, in which the adults’ value ranged from 0.00933% for Triadimefone to 3.97% for Prochloraz, while the children’s cHQ values ranged from 0.0162% for Triadimefone to 6.88% for Prochloraz. The highest chronic risk came from Prochloraz, which was higher than previous studies of risk assessment in fruit. In that study, the cHQ for Prochloraz of adults and children were 0.053% and 0.213%, respectively. However, in the research of the risk assessment of prochloraz in bayberries (Zhao et al. 2019), cHQ was calculated for adults to be 0.001 and aHQ of 0.82, and children’s aHQ was 0.57, which indicated acceptable chronic risks. However, both adults and children face intolerable acute hazards.
From both aHQs and cHQs, children have a higher exposure risk with fruit than adults. This is because children are lighter in body weight than adults and their fruit consumption is relatively high. In the research of 284 pesticide residues in five local fruits, including grapes in Shanghai (Zhang et al. 2021), it was found that through fruit consumption, children face greater risks than adults. This conclusion is also consistent with some other reports (Si et al. 2021; Chu et al. 2020; Mojsak et al. 2018. According to research, pesticides with a high detection rate do not always represent a significant danger of exposure (Qin et al. 2021). In our research, the most detected pesticides were Dimethomorph with a rate of 75.6%, but the HQs were only from 0.147–0.690%. In short, all the risk scores were below 100% in this study, suggesting that the potential dietary risks of nine pesticides from grapes to Chinese consumers are not significant. Pesticide residue levels in all foods studied had no effect on consumer health.
It's worth mentioning that the dietary exposure calculated in this study only covered grape exposures and not any other foods. Therefore, the total exposure to the pesticides studied was underestimated. On the other side, the possible processing before eating fruit is ignored. Zhao et al. (2019) discovered that washing fruits with tap water for one minute effectively removes pesticide residues on the surface. Grapes, for example, are frequently washed, soaked, and peeled before eating, which can contribute to an overestimation of pesticide residues intake (Chen et al. 2011).