Residue behavior and consumer risk assessment of spirotetramat and chlorpyrifos on cabbage heads and cropped soil.

A field experiment following good agricultural practices was laid out to study the dissipation of spirotetramat (90 g a.i. ha-1 and 180 g a.i. ha-1) and chlorpyrifos (400 g a.i. ha-1 and 800 g a.i. ha-1) on cabbage heads and soil. Samples were processed using quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for residue estimation of spirotetramat and chlorpyrifos, which were further detected using HPLC-PDA and GC-FPD respectively. The residues of spirotetramat on cabbage heads reached below detection limit (BDL) (< 0.05 mg kg-1) on 7th and 10th day and for chlorpyrifos, BDL (< 0.01 mg kg-1) was achieved on 10th and 15th day for X and 2X dose, respectively. On 20th day after second spray, residues in soil were found to be BDL for both the pesticides. Half-life of spirotetramat and chlorpyrifos was found to be 3 and 2 days, respectively while a safe pre-harvest interval (PHI) of 9 days for spirotetramat and 10 days for chlorpyrifos is suggested on cabbage. The dietary risk assessment studies for various age groups of Indian population, ascertained safety of treated cabbage heads for consumption, as current study revealed that hazard quotient (HQ) < 1 and theoretical maximum dietary intake (TMDI) < maximum permissible intake (MPI) for both the pesticides at respective PHI.

Residue estimation and dietary risk assessment of fenvalerate, novaluron, and profenofos in bell pepper grown under protected and open field conditions.

Residue studies were conducted in bell pepper crops (green and yellow bell pepper) to ensure the safe use of fenvalerate, profenofos, and novaluron (under open field and protected conditions) in randomized block design (RBD) following three applications at a 10-day interval over two consecutive years, 2021 and 2022. A robust analytical method was developed using quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and gas chromatography-tandem mass spectrometry (GC-MS/MS) for the determination of pesticide residues in bell pepper samples. The half-lives for fenvalerate were 2.47-2.87 and 2.50-3.03 days on bell pepper under open field conditions, whereas the corresponding values for bell pepper under protected conditions were 3.84-4.58 and 4.17-4.71 days, during 2021 and 2022, respectively. Profenofos displayed half-lives of 2.03-2.65 and 2.15-2.77 days in open field conditions and 3.05-3.89 and 3.16-3.78 days in protected conditions during 2021 and 2022, respectively. Similarly, novaluron had half-lives of 2.87-3.49 and 3.24-3.75 days under protected conditions in 2021 and 2022, respectively. The maximum residue limits (MRLs) were calculated to be 0.6 mg/kg for fenvalerate, while for profenofos it was 0.7 mg/kg on bell pepper under open field conditions at double doses, at the proposed pre-harvest interval (PHI) of 3 days. Likewise, for bell peppers grown under protected conditions, MRLs at the PHI of 3 days were determined to be 0.8 mg/kg for fenvalerate, 0.3 mg/kg for novaluron, and 1.5 mg/kg for profenofos. A dietary risk assessment study indicated that the percentage of acute hazard index (% aHI) was significantly lower than 100, and hazard quotient (HQ) values were below 1, signifying no acute or chronic risk to consumers. These findings underscore the safety of consuming bell peppers treated with fenvalerate, profenofos, and novaluron under the protected and open field conditions.

Residue behaviour and health risk assessment of chlorpyrifos and mancozeb in apple fruits and soil.

Mancozeb residue estimation was done using second derivative ultraviolet spectroscopy by Shimadzu ultraviolet-visible spectrophotometer, and chlorpyrifos was estimated by QuEChERS technique using GC-FPD. The persistence for chlorpyrifos was carried out at two locations, and for mancozeb, persistence studies were carried out at four locations. Initial deposits of mancozeb on apple fruits ranged from 1.33 to 1.63 mg/kg at the recommended dose and from 2.55 to 3.26 mg/kg at double the recommended dose at all four locations. Chlorpyrifos residues in apple fruits had an initial deposit of 0.94-0.99 mg/kg at recommended dose and 1.75-1.92 mg/kg at double the recommended dose. Mancozeb residues in apple fruit were below the detection limit (BDL) after 20 days at recommended dose and after 25 days at double the recommended dose at two locations, while mancozeb residue at the other two locations and the residues of chlorpyrifos at all locations reached BDL after 15 and 20 days at recommended and double the recommended doses, respectively. Half-life of mancozeb varied from 3.07 to 4.02 days at recommended dose and from 3.30 to 4.32 days at double the recommended dose, whereas chlorpyrifos residues dissipated to half their initial concentration on 2.33-2.35 days at recommended dose and 2.89-2.90 days at double the recommended dose. The soil samples showed no presence of residues of chlorpyrifos and mancozeb at harvest. The risk assessment revealed that hazard quotient for the intake of mancozeb was in the range of 0.06-0.13% and 0.20-0.44% for rural and urban population, while for the intake of chlorpyrifos, hazard quotient was in the range of 0.10-0.12% for rural population and 0.33-0.38% for urban population, and theoretical maximum dietary intake (9.67 × 10-5 mg/person and 3.18 × 10-4 mg/person for rural population and urban population in case of mancozeb and 3.22 × 10-5 mg/person and 1.06 × 10-4 mg/person for rural population and urban population in case of chlorpyrifos) was also found to be less than maximum permissible intake (1.38 mg/kg for mancozeb and 0.60 mg/kg for chlorpyrifos). The results of risk assessment thereby indicated that apple consumption does not pose a risk to human health.

Dissipation pattern and dietary risk assessment of some commonly used insecticides on tomato (Solanum lycopersicum L.).

Pesticide residue in food commodities is a serious concern in relation to consumer safety and also the most significant barrier in the trade of food commodities. The dissipation pattern of four insecticides, namely novaluron, λ-cyhalothrin, imidacloprid, and fenazaquin, was evaluated on tomato fruits and cropped soil. The residues were extracted using the QuEChERS analytical method and quantized using a gas chromatograph with electron capture detector, gas chromatograph mass spectrometer, and high-performance liquid chromatography with photo diode array detector. The analytical method was validated using parameters like recovery, linearity, accuracy, matrix effect, and specificity, with limit of detection and limit of quantitation established to be 0.01 and 0.05 mg/kg, respectively, for all the pesticides. The average initial deposits (samples collected after 2 h of application) at the recommended dose of novaluron, λ-cyhalothrin, imidacloprid, and fenazaquin were 0.593, 0.293, 0.227, and 0.431 mg/kg on tomato fruits, respectively, and were below the limit of quantification in soil. The pre-harvest interval of 17, 8, 1, and 13 days was suggested for novaluron, λ-cyhalothrin, imidacloprid, and fenazaquin on tomato, respectively. Risk assessment studies revealed that all pesticides under study are safe and do not pose any threat to humans as theoretical maximum dietary intake is less than the maximum permissible intake and acceptable daily intake.

Dissipation kinetics and dietary risk assessment of spiromesifen on major summer vegetables using good agricultural practices.

Dissipation kinetics and dietary risk assessment of spiromesifen is worked out on four summer vegetables, viz. okra, chilli, capsicum and brinjal (eggplant or aubergine) during March-April 2015 at the experimental farm of the Department of Entomology, Dr. Yashwant Singh Parmar University of Horticulture and Forestry Nauni, Solan using good agricultutral practices. Two foliar applications of spiromesifen @ 144.0 g.a.i./ha each were given at 10 days interval with a knapsack sprayer with the first application at the fruit initiation stage. Sample were collected up to 15 days after pesticide application and processed using a modified QuEChERS method, which was validated by doing recovery studies having recovery range and RSD within established guidelines of SANCO. Estimation of spiromesifen residues was conducted on GC-MS. The initial deposits after spraying of spiromesifen on okra, capsicum, chilli and brinjal fruit after 2 h of treatment were 1.327, 0.727, 0.800 and 0.738 mg/kg, respectively. The residues persisted up to 7 days and further dissipated and declined below the limit of quantification of <0.025 mg/kg at 10 days after treatment in all of the crops under investigation. Dissipation of spiromesifen followed first-order kinetics. The spiromesifen residues dissipated to half in 1.6, 1.8, 1.9 and 1.7 days with the suggested safe waiting period of 8.9, 5.2, 6.0 and 7.0 in the respective crops. The hazard quotient was <1 and theoretical maximum dietary intake was less than the maximum permissible intake, which was less than the maximum residue limit in all of the vegetable crops under investigation.

Dissipation kinetics and consumer risk assessment of novaluron + lambda-cyhalothrin co-formulation in cabbage.

Cabbage, one of the most popular vegetables in the world is infested by several insect-pests and diseases. Novaluron, a chitin synthesis inhibitor and lambda-cyhalothrin, a synthetic pyrethroid group insecticide are used to manage insect-pests on cabbage. The dissipation kinetics and risk assessment of combination formulation (novaluron 9.45% + lambda-cyhalothrin 1.9%) with different modes of action has not yet been investigated in cabbage. Multi-location supervised field trials were therefore, conducted in different agro-climatic regions of India for safety evaluation of the combination product. The co-formulation at the recommended (novaluron 750 g a.i. ha-1 + lambda-cyhalothrin 750 g a.i. ha-1) and double the recommended (novaluron 1500 g a.i. ha-1 + lambda-cyhalothrin 1500 g a.i. ha-1) dose was sprayed on the cabbage crop. The samples were extracted and cleaned up using a modified QuEChERS method, and the residues analyzed by GC-ECD and GC-MS. The half-life (t1/2) varied between 1.77 and 2.51 and 2.00-3.38 days for novaluron and 1.36-2.24 and 1.69-3.82 days for lambda-cyhalothrin in cabbage at respective doses. The Food Safety and Standards Authority of India (FSSAI) has set the MRL of 0.7 mg kg-1 for novaluron at PHI of 5 days, and no MRL is set for lambda-cyhalothrin in cabbage. On the basis of OECD MRL calculator, the MRLs of 0.6 and 1.5 mg kg-1 for novaluron and lambda-cyhalothrin, respectively were calculated at the respective doses at PHI of 3 days. Hazard quotient (HQ) <1, theoretical maximum daily intake (TMDI) < acceptable daily intake (ADI) and < maximum permissible intake (MPI), percent acute hazard index (% aHI) <1, and percent chronic hazard index (% cHI) <1 for both novaluron and lambda-cyhalothrin suggested that the combination formulation is safe and will not pose any dietary risk to the consumers. The study will be helpful to conduct risk assessment of other pesticides/combination pesticides on food crops on which their MRLs have not yet been fixed.

Persistence and dissipation kinetics of tebuconazole in apple, tomato, chilli and onion crops of Himachal Pradesh, India.

Tebuconazole is a broad-spectrum fungicide extensively used worldwide for the control of many diseases such as powdery mildew and scab in apple, early blight of tomato, anthracnose of chilli, white rot and purple blotch of onion etc. Maximum residue level of this compound has not been worked out on these crops in India; the persistence and dissipation kinetics of tebuconazole on apple, tomato, chilli and onion were studied following three foliar applications of the formulation Folicur 430 SC at a standard dose (X) 322, 268.75, 215 and 215 g a.i./ha and at double dose (2X) 645, 537.5, 430 and 430 g a.i./ha, respectively, to work out the safe waiting periods and half-life period of tebuconazole. Extraction was done using QuEChERS method and cleanup by using dispersive solid-phase method. Tebuconazole residues were estimated on gas chromatograph-mass spectrometry (GC-MS). The recovery of tebuconazole in fortified matrix was above 90% with a limit of quantification (LOQ) at 0.05 mg kg-1. The initial deposits of tebuconazole on apple at two locations under study ranged from 1.986-2.011 mg kg-1at X dose to 3.698-3.843 mg kg-1 at 2X dose. The initial deposits in tomato, chilli and onion were 1.129, 1.760 and 1.169 mg kg-1 at X dose and 2.213, 2.784 and 2.340 mg kg-1, respectively at the 2X dose. Dissipation of the fungicide followed first-order of kinetics and the half life of degradation ranged from 1.30-2.25 days at X dose to 1.40-2.62 days at 2X days on different crops under study. Residues declined below the determination limit (LOQ) of 15 and 20 days after spraying, respectively, at X and 2X dose in apple; 7 and 10 days in tomato; 10 and 15 days in chilli and onion. Waiting periods of 5, 2, 7 and 12 days, respectively, are suggested for apple, tomato, chilli and onion at 2X dose.

Persistence of tetraniliprole and reduction in its residues by various culinary practices in tomato in India.

A field experiment was conducted to study the persistence and dissipation pattern of a new molecule tetraniliprole on tomato fruits and soil. Tetraniliprole was sprayed at the rate of 60 g a.i. ha-1 and 120 g a.i. ha-1on the tomato crop. Tomato fruit samples were analyzed as per the method described by Bosta and Nageswara (Asian J Res Chem 8:383-388, 2015). The residues of tetraniliprole and its metabolite chinazolinon were estimated on HPLC equipped with RP C18 column and photo diode array detector. Initial deposits of tetraniliprole were 0.865 and 1.747 mg kg-1 on fruits and 0.092 and 0.177 mg kg-1 in the soil, respectively, from the two treatments at the rate 60 g a.i. ha-1 and 120 g a.i. ha-1. The residues on fruits dissipated to half in 2.7 and 3.49 days, respectively. Based on the persistence studies, a waiting period of 15 days is suggested on tomato fruit from consumer's safety point of view. The pesticide residues, left to a variable extent in the tomato after harvesting, are beyond the control of consumers and have deleterious effects on human health; hence, their residues reduction by various culinary processes were highlighted. Treated tomato fruit samples collected at 1, 3, and 5 days after application were also subjected to common household practices. Washing of tomato fruits by tap, lukewarm, and saline water reduce tetraniliprole residues up to 37.63, 44.67, and 61.49%, respectively. Microwave cooking of tomato provided >12% better relief from tetraniliprole residues in comparison with open pan cooking of 72.21%. Chinazolinon residues, a metabolite of tetraniliprole, were not detected in any analyzed processed tomato fruit sample.

Residue dynamics and risk assessment of Luna Experience® (fluopyram + tebuconazole) and chlorpyrifos on French beans (Phaseolus vulgaris L.).

The persistence of chlorpyrifos, fluopyram, and tebuconazole was estimated in green pods, matured seeds, and soil of French beans using dispersive QuEChERS. Three foliar applications each of chlorpyrifos and a combination fungicide fluopyram + tebuconazole (Luna experience, 400 SC) were applied at 600 and 125 + 125 as a standard dose and 1200 and 250 + 250 g a.i. ha-1 as a double dose, respectively, were applied at an interval of 10 days and treated pods were picked up at regular intervals. Dried mature seeds and soil were also monitored at harvest. The initial deposits of chlorpyrifos on bean pods were 3.083 and 6.017 mg kg-1 with a half-life of 1.86 and 2.29 days, at respective doses. Foliar application of a combi product Luna experience yielded 3.396 and 5.772 mg kg-1 residues of fluopyram and 3.613 and 5.887 mg kg-1 of tebuconazole in green pods at standard and double dose with almost same half-lives of 3.4 and 3.8-3.9 days. Residues declined below the limit of quantitation (LOQ) of 0.05 mg kg-1 in green beans after 15 and 25 days after the application of double dose of chlorpyrifos and Luna experience, respectively. However, the residues in dry bean seeds and soil reached below the LOQ of 0.05 mg kg-1 at the time of harvest. A pre-harvest interval of 5, 10, and 7 days has been proposed for chlorpyrifos, fluopyram, and tebuconazole, respectively, in beans. HQ < 1 and TMDI < MPI in all test chemicals. Hence, it was concluded that a waiting period of 5 days for chlorpyrifos and 7-10 days in Luna experience will be safer to consumers. This data generated will be useful for regulatory agency for fixing MRLs.