Organochlorine pesticide residues monitoring and human health risk evaluation in agricultural crops from Ilam Province, Southwest of Iran

Abstract

The issue of food supply and security remains a major challenge and crisis for the world’s growing population. In this study, a comprehensive analysis of the residues of fourteen organochlorine pesticides (OCPs) was conducted and detected using gas chromatography with an electron capture detector (GC/ECD) in sixty-one samples of twelve crops produced in ten counties within Ilam Province, southwest Iran. The samples included lentils, chickpeas, wheat, tomatoes, corn, rice, cucumbers, watermelons, melons, cantaloupes, edible (raw) vegetables, and stewed vegetables. The levels of all detected OCP residues in the twelve crop types were below the maximum residue limits (MRLs) established by Iran and the Food and Agriculture Organization/World Health Organization (FAO/WHO) (50 µg/L). Lindane, Endrin, and Heptachlor were detected at the highest concentrations of OCPs across all crops, while Methoxychlor and Endosulfan were found at the lowest levels. No prior studies have focused specifically on detecting the presence of OCPs in certain products such as lentils and chickpeas, making this study unique in its findings. The target hazard quotient (THQ) and hazard index (HI) were used to estimate human health risk assessment (HRA) associated with OCP residues in the samples. The results indicated that the HI value was lower than 1 in both adults and children for all samples, suggesting no considerable risk for consumers. Overall, stringent control programs, integrated pest management, quality control, and periodic monitoring of crops before they are released to the market are essential.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-026-43702-6.

Introduction

The urbanization and population growth led to increment demand to food and agricultural crops and resulted to uncontrolled use of chemical fertilizers and pesticides to meet the increasing world food demand^1,2. Today, food security and safety are a global concern that has become increasingly important for consumers of agricultural products. Food pollution in developing countries is 13% higher than in developed countries, with industrial factors and agricultural activities, such as the use of chemical fertilizers, animal manures, compost, and pesticides, being among the contributing factors^2–4. Agriculture is a cornerstone of sustainable development and is vital for human survival, as it is the primary source of food and basic commodities. Pesticides are extensively applied in agricultural systems to manage pest populations and protect crop productivity. It is estimated that the use of pesticides preserves approximately 33% of global agricultural production by preventing yield losses and on the other hand, about 45% of global crop production is lost each year due to damage caused by insect pests and plant diseases, illustrating the ongoing challenges faced by agriculture in ensuring food security for a growing population^4,5.

Over the past three decades, global pesticide use has risen by more than 1.5 times. It is reported that worldwide annual use of pesticide is about two million tonnes and it estimated that increased to 3.5 million tonnes by the year 2020. Asian countries account for the majority of this consumption, representing approximately 53% of worldwide pesticide use, followed by the Americas at 30% and Europe at 14%^2,6. China is one of the world’s largest pesticide users and the major contributing country, with application rates rising from 0.76 × 10⁹ kg in 1991 to 1.8 × 10⁹ kg in 2011. Over 14 kg/ha are applied annually to cultivated land in China, far exceeding rates in the USA (2.2 kg/ha), France (2.9 kg/ha), and the Netherlands (8.8 kg/ha)^7,8. Approximately 24.5 million square kilometers of agricultural land in the world (about 64%) is at the risk of different class of pesticide pollution because of more than one active chemical, and 31% of agricultural land is reported as at high risk^9,10.

Several studies indicated that more than 80% of pesticide residues especially OCPs are chemical compounds with the highly hazard and serious risks to the human health such as poisoning, autism and behavioral disorders, diabetes, cancer, abortion, skin and neurological complications and cardiovascular diseases, and surrounded environment, due to the excessive use of them in the farm and agricultural products^1,6,11–14. It is reported that annual use of pesticides that sprayed on the agricultural crops including vegetables and Fruits is 140,000 tons in the European Union (EU). Based on the EUs data in the Pesticide Action Network, some 350 various kinds of pesticides were identified in food produced in the EU and levels of pesticides in the agricultural crops were detected that higher than the EUs maximum permitted level (MPL) in the 5 percent of products. Vegetables and Fruits play an important role in the human diet due to being a suitable source of vitamins, antioxidants, fibers and minerals, the World Health Organization (WHO) has reported that they account for more than 30% of the diet consumed in Europe¹⁵.

Farmers all over the world, especially in modern agricultural systems, frequently use a wide range of chemical pesticides, including OCPs, to combat pests and plant pathogens. These pesticides, which are characterized by low biodegradability and prolonged persistence in the environment, can remain on the surface of agricultural products and even penetrate their tissue, including fruits, vegetables, and seeds. Cereals are also susceptible to contamination with these types of pesticides^16–18.

Pesticides play a vital role in controlling crop pests and diseases, regulating plant growth, increasing productivity, and improving crop quality. Pesticides are a mixture of chemical compounds that is used to eliminate, prevent, control or reduce the damage caused by a pest in agriculture and households, and it can be a chemical substance (synthetic or natural), a biological agent (such as a virus or bacteria) or any kind of it is a means of destroying pests (insects, pathogenic plants, weeds and nematodes)^6,9. The pesticides are capable to control the quality and the quantities of agricultural crops, products and food, and enable to limit the transmission of various human diseases via insect/rodent related vector. The application of different type of pesticide is essential in the modern agriculture from two aspects i.e. to increase yield of crops and to control of pest. However, despite of this positive role of them, pesticide is considered as the chemical compounds with high toxicity, mobile and environmentally stable compounds in the environment. Therefore, the inappropriate use and misuse of pesticides is one of the most important and serious threats to the stability of chemical pest control, the health of farmers and the contamination of the environment with toxic chemical compounds^7,9,15,19,20.

Due to the different chemical structures, applications and mode of actions of the pesticides, they categorized in the various classification (more than 30 class) according to the following criteria including structure of chemical compound, stability in the environment, purpose of application; toxicity and mode of action against the target organism^14,21. Generally, they can be divided into two different groups based on their chemical structure including organic and inorganic compounds. In this monitoring study, the organochlorine pesticides (OCPs) as organic compounds were evaluated.

Organochlorine pesticides (OCPs) are synthetic, highly persistent, lipophilic organic compounds that were introduced into the environment in the late 1940s. They were widely used in agriculture and public health programs due to their effectiveness in controlling pests and vector-borne diseases. However, their environmental persistence, bioaccumulation and biomagnify in food chains, and long-range transport led to widespread contamination of various environmental matrices, including soil, water, air, and biota^10,12,13,22. OCPs are a diverse group of chemical compounds that due to their cost –effectiveness and highly efficient effects on the pest, they have been widely used in the few past decades. OCPs are one of the most important organic pesticides and form a large class of insecticides^15,22. The use of OCPs for agricultural and public health purposes in the world has caused widespread environmental pollution. OCPs due to the high toxicity nature, considerable stability and transport in the environment (as long as 30 years), persistence in the environment and capability to transfer by water and air and over long distances, and bioaccumulation and bio-magnification in the food web are considered as the very important threats to human health and wildlife as well as the environment^17,20,23. Several OCPs are classified by IARC and the U.S. EPA as possible or probable human carcinogens, including heptachlor and dieldrin (Group 2A) and lindane, Aldrin, Endrin, DDTs, and Endosulfan (Group 2B). Given that dietary exposure is chronic and cumulative, the carcinogenic potential of these compounds should be considered when interpreting health risks, even when non-cancer indicators remain below threshold levels^24,25. Due to the above-mention characteristics of OCPs compounds such as dichlorodiphenyltrichloroethane (DDTs), lindane and Aldrin, the use of them was prohibited by considering the Stockholm Convention, which considered OCPs as one of the original 12 persistent organic pollutants (POPs)^17,20,26. OCPs are still found in the environment and subsequently in the agricultural crops due to their environmental stability.

Different crop categories vary in their ability to absorb OCPs from soil and irrigation water, with leafy and root vegetables generally exhibiting higher accumulation potential. Considering these characteristics helps in selecting representative matrices for exposure assessment. Numerous studies have investigated the occurrence of OCPs in agricultural products across Iran, including assessments in soils, fruits, vegetables, and cereals. Previous reports have identified detectable OCP levels in regions such as Bushehr¹⁷, Hamadan¹⁹, and West Azerbaijan (the city of Urmia)²⁷, with certain residues exceeding national or international permissible limits. Similar monitoring studies conducted in China^10,16, India⁴, Pakistan^28,29, and other Middle Eastern (Saudi Arabia) countries³⁰ have documented persistence of DDTs, HCH isomers, Aldrin, Dieldrin, and Endosulfan in various crops. However, limited data exist regarding OCP contamination in agricultural products of Ilam Province except pervious study conducted by our team³¹, and No published studies were found evaluating OCP residues in lentils or chickpeas staple crops with high regional consumption either in Iran or globally. Furthermore, systematic dietary risk assessments focusing on OCP exposure in southwestern Iran remain scarce^1,32.

Taking this in the mind, one of the most important and high priorities challenges for worldwide sustainable development is food safety/security and monitoring the agro-products and crops to detection of pesticides and evaluation of the health risk of them should be addressed. Given the widespread use, environmental persistence, and potential health impacts of OCPs, understanding their presence in agricultural products is essential for evaluating consumer exposure and ensuring food safety. The practical goal of this research is to provide reliable, region-specific baseline data on OCP residues in agricultural crops produced in Ilam Province. By evaluating 14 OCPs across 12 commonly consumed crops including lentils and chickpeas, for which no prior monitoring data exist, this study aims to support food safety authorities in establishing effective surveillance and regulatory programs. The findings are intended to guide policymakers, agricultural organizations, and farmers in improving pesticide management practices, strengthening integrated pest management (IPM), and reducing potential human exposure. Ultimately, this work contributes practical evidence needed for safer crop production, sustainable agriculture, and the protection of public health in the region.

Given these gaps in regional monitoring data, the present study aims to: (i) quantify the residual concentrations of fourteen commonly used OCPs in twelve major agricultural crops produced across ten counties of Ilam Province; (ii) compare detected residues with national maximum residue limits (MRLs); and (iii) assess the potential non-carcinogenic dietary exposure risk for adult and child consumers using established health risk assessment (HRS) model. This work provides the first comprehensive dataset on OCP contamination in several locally important crops, including lentils and chickpeas, and contributes essential evidence for regional food safety management and pesticide regulation.

Materials and methods

Reagents and chemicals

During the whole study, the water produced by Milli-Q water purification system (Millipore, Bedford, MA, USA) was used throughout all experiments. The chemical and solvents used to instrumental analysis of the pesticides be HPLC grade and used as received including cyclohexane (> 99.8%), dichloromethane (99.9%), methanol (99.85%), acetone (99.5%), hexane (95%), sodium chloride (99.5%) and sodium sulfate (99.0–100%) (Sigma-Aldrich).

Study area description and agricultural crops sample collection

This study was conducted in Ilam province with a population of 580,158 people, which is located in the southwest of Iran. The area of province is 20,164.11 km² and its elevation above sea level is varied between 136 to 1450 m. Ilam province consists of 10 counties including Ilam, Dehloran, Sirvan, Ivan, Badreh, Abdanan, Malekshahi, Mehran, Darehshahr, and Chardavol (Fig. 1). The average annual rainfall of the province is 446.8 mm and there are different climatic variations in summer (hot and dry) and winter (cold). With 340 ha of agricultural land, the province plays an important role in the production of agro-products and crops, so the main occupation of the people in this province is agriculture and husbandry. The agricultural crops and products are usually export to other regions.

Fig. 1.

Shematic diagram of sampling locations in ten counties of Ilam Province, Southwest of Iran.

Sample collection and preparation for analysis

In the present study, 61 samples of 12 types of agricultural products that have the highest production in Ilam counties were randomly collected from local farms and major production (Table 1). The agricultural products were then transferred to the laboratory and were kept in the refrigerator (4˚C) until extraction and further experiments. Table 1 shows the samples of agricultural crops produced in different counties of Ilam province (The proposed list of the Ilam Agricultural Organization). The selection of agricultural products was based primarily on their high consumption and production rates in Ilam Province, ensuring that the assessed crops reflect the main dietary exposure pathways for the local population. In addition, the potential of these crops to absorb and accumulate OCPs from soil and irrigation water was also considered. Leafy vegetables, root crops, and fruit vegetables are known to have higher uptake capacities for POPs, and therefore their inclusion supports a more realistic estimation of human exposure. The weight of the collected agricultural crops samples for experiment was 200–500 gr for cereals (grains), 500 gr for vegetables, 1 kg for summer vegetables (such as tomatoes) and one for watermelon, melon, and cantaloupe. A suitable amount (100 gr) of vegetables and herbs was chopped with an appropriate chopper (Fig. 2A). The mill was used to powder grains such as peas, lentils, etc. Then, 50 gr of crushed or powdered sample was introduced into a glass container and 105 ml of dichloromethane was added to the previous solution and homogenized with a magnetic stirrer for 2 min. After the above time, 80 gr of anhydrous sodium sulfate was added to the previous solution. The above mixture was kept at rest in the laboratory for 2 min. After that, according to Fig. 2B, in order to separate solid parts of the samples, such as vegetables, etc., from the liquid sample, the mixture was filtered using a filtration set (12-cm Buchner funnel). Then, the filtered sample was again passed through the sodium sulfate column containing the filter (at its bottom). The obtained solution was completely dried in oven at 35–40 °C and 5 ml of cyclohexane solution was added to the dried residue sample. Finally, the sample was prepared in a glass tube with a lid to be injected into the GC-ECD to measure the amount of pesticide³³.

Table 1.

Samples of agricultural crops produced in different Counties of Ilam province (The proposed list of the Ilam Agricultural Organization).

No	Crops	Counties of Ilam province	No. of samples
1	Wheat	Ilam, Dehloran, Abdanan, Mehran, Darehshahr, Malekshahi, Sirvan, Chardavol, Ivan	Ten samples
2	Rice	Darehshahr, Chardavol, Sirvan, Ivan	Four samples
3	Corn	Darehshahr, Dehloran, Mehran	Three samples
4	chickpea	Ilam, Chardavol, Sirvan, Ivan, Dehloran, Mehran	Six samples
5	Lentil	Ilam, Chardavol, Sirvan, Ivan, Dehloran, Mehran	Six samples
6	Tomato	Ilam, Dehloran, Mehran, Abdanan, Darehshahr, Malekshahi, Sirvan, Chardavol, Ivan	Nine samples
7	Eating vegetables	Ilam, Dehloran, Mehran, Darehshahr, Chardavol	Five samples
8	Stewed vegetables	Ilam, Dehloran, Mehran, Darehshahr, Chardavol	Five samples
9	Cucumber	Dehloran, Darehshahr, Chardavol	Three samples
10	Cantaloupe	Dehloran, Darehshahr, Chardavol, Sirvan	Four samples
11	Watermelon	Dehloran, Darehshahr, Chardavol, Sirvan	Four samples
12	Melon	Dehloran, Darehshahr	Two samples
Total samples	61 samples

Fig. 2.

(A) Crushed the crops samples for measuring pesticide; (B) Filtration of samples in order to prepare for pesticide measurement.

Analysis, extraction and detection of OCPs by GC-ECD

First, 90 ml of water was placed in a special glass container and 10 µL of internal standard PCB29 with a concentration of 10 ppm and some sodium chloride salts were added to it. After mixing, 1 ml of hexane was added to it again. Then it was mixed for 20 min on a magnetic stirrer at a suitable speed, so that the exchange between the two phases is done completely. In this case, the hexane phase appears as a conical droplet. After 20 min, while the glass container is still rotating, remove the lid and draw the hexane phase with a Pasteur pipette and pour it into the vial. The sample is ready to be injected into the GC-ECD. Analysis and detection of OCPs were carried out using a GC equipped an electron capture detection (ECD) on an HP 6890 Plus gas chromatograph with a Capillary, HP-5MS (Agilent Technologies, USA), (Length: 30m internal diameter, Diameter: 0.25mm, Film thickness: 0.25µm). Injection technique and temperature was splitless and 290ºC. The carrier gas was the helium gas with a flow rate of 1 mL/ min with the injection volume of 2µl. The injection temperature was set at 290 °C and the temperature program for oven was performed as follows: Increase the temperature to 110 °C for 5 min, then 5 °C/min to 280 °C for 10 min. A relative retention time for detection of OCPs was 0.005 min which was similar to detection time of the standard pesticide^17,20,33. Method validation was performed following standard pesticide residue analytical guidelines. Calibration curves were prepared using standard solutions at 20, 50, 100, and 200 ppb, yielding excellent linearity (R² > 0.99). Recovery studies were conducted by spiking blank crop matrices at three fortification levels (20, 50, and 100 µg/kg), representing low, medium, and high concentrations relative to the national MRL. Each spiking level was analyzed in triplicate (n = 3). Mean recoveries ranged between 70 and 120% with relative standard deviation (RSD) values below 20%, meeting the acceptance criteria for pesticide residue analysis. Limits of detection (LOD) and quantification (LOQ) were calculated based on signal-to-noise ratios of 3 and 10, respectively. The method validation was carried out with the parameters of limit of quantification (LOQ), the limit of detection (LOD), RSD and Recovery (%) which depicted in the Table 1S.

Health risk assessment (HRA)

The HRA process is associated to pollutants exposure assessment. In this regard, target hazard quotient (THQ) is one of the most important parameters of HRA regarding the ingestion of vegetables and fruits (agricultural crops). The acceptable daily intake (ADI) values for all OCPs were sourced from the European Food Safety Authority (EFSA) peer-reviewed pesticide assessments and the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) toxicological evaluations. The estimation of daily intake (EDI) followed the dietary exposure methodology recommended by JMPR, while the THQ and hazard index (HI) equations were adopted from the United States Environmental Protection Agency (USEPA) Risk Assessment Guidance^25,34. In this study, the EFSA/ the JMPR were used to calculate the ADI for assessing the HRS Eq. (1) (Table 2).

1

Table 2.

Required parameter values for calculate EDI and THQ in Health risk assessment.

Parameters	Unit	Adult	Children
Exposure frequency (EF)	(day/year)	350	350
Average lifetime (AL)	(days)	10,950	2190
Exposure duration (ED)	(years)	30	6
Body weight (BW)	(kg)	70	15
Ingestion rate (IR)	(kg day)
Lentil	(kg day)	0.015	0.0045
Chickpea	(kg day)	0.015	0.0045
Wheat	(kg day)	0.334	0.100
Rice	(kg day)	0.110	0.033
Corn	(kg day)	0.001	0.0003
Tomato	(kg day)	0.025	0.0075
Eating (raw) vegetables	(kg day)	0.0135	0.0045
Stewed vegetables	(kg day)	0.013	0.004
Cucumber	(kg day)	0.015	0.0045
Cantaloupe	(kg day)	0.015	0.0045
Watermelon	(kg day)	0.020	0.006
Melon	(kg day)	0.015	0.0045

The calculation of EDI (estimation of daily intake, in terms of mg/kg.day) were calculated using Eq. (2):

2

Where, IR, EF, ED, PR, AL and BW are per capital agricultural crops ingestion rate (kg/day), exposure frequency, exposure duration and concentration of reported pesticide residue (PR) in the agricultural crops in this study (mg/kg), average lifetime, and Body weight, respectively (Table 2). The health risk assessment was calculated by hazard index (HI) based on the sum of all pesticides in the different agricultural crops using following Eq. (3):

3

Where, HQ is the hazard quotient for each one of the OCPs pesticides. Based on the Eq. (3), if the value of HI and/or HQ was equal to 1 and less than 1, health risk by pesticides for consumer is considered acceptable and if the value of HI and/or HQ was higher than 1, the health risk is a considerable concern for consumers ^35–27. In addition to non-carcinogenic health risk calculations (EDI, THQ, HI), we reviewed the carcinogenic classifications of all analyzed pesticides based on IARC and USEPA (Table 2S)^24,25. It indicates which OCPs are considered: IARC Group 1—Carcinogenic to humans: None of the analyzed OCPs fall in Group 1, IARC Group 2A—Probably carcinogenic to humans: Heptachlor and Dieldrin. IARC Group 2B—Possibly carcinogenic to humans: Lindane (γ-HCH), DDTs (including DDE, DDD, p,p-DDT), Aldrin, Endrin and Endosulfan. Not classifiable (Group 3): Methoxychlor, Endrin ketone and Endrin aldehyde.

Result and discussion

Although the detected OCP concentrations were generally low and mostly below the national MRLs, the representativeness of the dataset is limited. Several crops were represented by only one or two samples in certain counties, largely due to seasonal availability and difficulties accessing farms during the sampling period. As a result, the observed residue levels should be interpreted as preliminary indicators rather than comprehensive estimates of pesticide contamination across Ilam Province. In this study, the residual concentrations of fourteen OCPs were analyzed across 61 samples of 12 agricultural crops collected from 10 counties in Ilam Province. The findings and their comparison with existing literature are presented and discussed below.

In this study, a comprehensive analysis of fourteen OCPs residues was conducted using GC/MS techniques in 61 samples of 12 types of agricultural crops cultivated across various counties in Ilam province, located in the southwestern region of Iran. These products include lentils, chickpea, corn, wheat, rice, tomato, edible vegetable, stewed vegetable, melon, watermelon, cucumber and melon. The OCPs investigated in this study were alpha-lindane, lindane, delta-lindane, heptachlor, Aldrin, epoxy heptachlor, D.D.E, dieldrin, D.D.D, Endrin aldehyde, Endrin ketone, methoxychlor, Endrin, and Endosulfan. Notably, the detected residual concentrations of all OCPs in the all agro-products cultivated in the various counties of Ilam province were found to be below the permissible limit (MRLs) of 50 μg/kg as set by the Iran national standard. Tables 3S to 7S present the residual concentrations of OCPs detected in various agricultural crops produced in various counties of Ilam province, Iran.

Table 3S presents the residual concentration (μg/kg) of 14 OCPs in lentil and chickpea samples from various counties (Ilam, Dehloran, Mehran, Chardavol, Ivan, and Sirvan) of Ilam province. As shown in Table 3S, Endrin aldehyde, Endrin ketone, methoxychlor, and Endosulfan pesticides were not detected in Lentil and chickpea agro-products cultivated in the counties of the province. The highest concentrations of OCPs (μg/kg) in the lentil products were 0.179 μg/kg for Delta-lindane in Sirvan, followed by 0.166 μg/kg for Endrin in Sirvan, and 0.146 μg/kg for Heptachlor in Ilam. The highest concentration of OCPs (μg/kg) in the chickpea was 0.689 μg/kg for Endrin in Mehran city, followed by 0.567 μg/kg for Endrin in Chardavol and 0.197 μg/kg for Heptachlor in Mehran city. The concentrations of OCPs in 100% measured samples were below the national MRLs, indicating that lentil and chickpea products had low residual contamination of OCPs. Among the investigated OCPs, Endrin, Heptachlor, and Delta-lindane were the most important in terms of residual concentrations in this work. It appears that no prior studies have focused specifically on detecting the presence of OCPs in lentil and chickpea products, making this study unique in its findings. The absence of related research highlights the need for further investigation into the occurrence and potential health risks associated with pesticide residues in these crops.

Table 3.

Health risk assessment for adult and child consumers due to pesticide intake from twelve agricultural products (based on the maximum concentration of each pesticide detected in the agricultural products from different counties).

Agriculture crops	Pesticide		Maximum concentration (mg/kg) (county)			ADI (mg/kg.day)		EDI (mg/kg.day)				THQ				HI
Lentil	Alpha-lindane		1.28E−04 (Mehran)			0.008		2.63E−08		3.68E−08		3.29E−06		4.60E−06		7.33E−04		1.03E−03
	Lindane		5.70E−05 (Mehran)			0.008		1.17E−08		1.64E−08		1.46E−06		2.05E−06
	Delta-lindane		1.79E−04 (Sirvan)			0.008		3.68E−08		5.15E−08		4.60E−06		6.44E−06
	Heptachlor		1.46E−04 (Ilam)			0.0001		3.00E−08		4.20E−08		3.00E−04		4.20E−04
	heptachlor Epoxy isomer		1.80E−05(Mehran)			0.0001		3.70E−09		5.18E−09		3.70E−05		5.18E−05
	D.D. D		2.00E−05 (Chardavol)			0.01		4.11E−09		5.75E−09		4.11E−07		5.75E−07
	Aldrin		1.04E−04 (Ilam)			0.0001		2.14E−08		2.99E−08		2.14E−04		2.99E−04
	Endrin		1.66E−04(Sirvan)			0.0002		3.41E−08		4.78E−08		1.71E−04		2.39E−04
	D.D. E		6.10E−05 (Chardavol)			0.01		1.25E−08		1.75E−08		1.25E−06		1.75E−06
Chickpea	Alpha-lindane		5.50E−05(Mehran)			0.008		1.13E−08		1.58E−08		1.41E−06		1.98E−06		1.35E−03		1.89E−03
	Lindane		9.80E−05(Chardavol)			0.008		2.01E−08		2.82E−08		2.52E−06		3.52E−06
	Delta-lindane		2.90E−05(Ivan)			0.008		5.96E−09		8.34E−09		7.45E−07		1.04E−06
	Heptachlor		1.97E−04(Mehran)			0.0001		4.05E−08		5.67E−08		4.05E−04		5.67E−04
	Aldrin		4.00E−05(Chardavol)			0.0001		8.22E−09		1.15E−08		8.22E−05		1.15E−04
	heptachlor Epoxy isomer		3.60E−05(Mehran)			0.0001		7.40E−09		1.04E−08		7.40E−05		1.04E−04
	D.D. D		6.00E−06(Ivan)			0.01		1.23E−09		1.73E−09		1.23E−07		1.73E−07
	D.D. E		5.30E−05(Ivan)			0.01		1.09E−08		1.52E−08		1.09E−06		1.52E−06
	Endrin		6.89E−04 (Mehran)			0.0002		1.42E−07		1.98E−07		7.08E−04		9.91E−04
	Dieldrin		3.50E−05 (Sirvan)			0.0001		7.19E−09		1.01E−08		7.19E−−05		1.01E−04
Corn	Alpha-lindane		4.20E−05(Mehran)			0.008		5.75E−10		8.05E−10		7.19E−08		1.01E−07		6.50E−05		7.45E−05
	Lindane		1.90E−05(Mehran)			0.008		2.60E−10		3.64E−10		3.25E−08		4.55E−08
	Delta-lindane		1.34E−04(Mehran)			0.008		1.84E−09		2.57E−09		2.29E−07		3.21E−07
	Heptachlor		1.92E−04(Mehran)			0.0001		2.63E−09		3.68E−09		2.63E−05		3.68E−05
	Aldrin		3.50E−05(Mehran)			0.0001		4.79E−10		6.71E−10		4.79E−06		6.71E−06
	heptachlor Epoxy isomer		1.20E−05(Mehran)			0.0001		1.64E−10		2.30E−10		1.64E−06		2.30E−06
	D.D. E		2.52E−04(Mehran)			0.01		3.45E−09		4.83E−09		3.45E−07		4.83E−07
	Dieldrin		1.35E−04(Mehran)			0.0001		1.85E−09		2.59E−09		1.85E−05		2.59E−05
	D.D. D		1.60E−05 (Darehshahr)			0.01		2.19E−10		3.07E−10		2.19E−08		3.07E−08
	Endrin ketone		4.1E−05 (Dehloran)			0.0002		5.62E−10		7.86E−11		2.81E−06		3.93E−07
	Endrin		1.51E−04 (Darehshahr)			0.0002		2.07E−09		2.90E−10		1.03E−05		1.45E−06
	Methoxychlor		2.20E−05 (Mehran)			0.1		3.01E−10		4.22E−10		3.01E−09		4.22E−09
Wheat	Alpha-lindane		6.30E−05(Mehran)			0.008		2.88E−07		4.03E−07		3.60E−05		5.03E−05		2.85E−02		3.99E−02
	Lindane		1.55E−04 (Dehloran)			0.008		7.09E−07		9.91E−07		8.86E−05		1.24E−04
	Delta-lindane		4.40E−05(Ilam)			0.008		2.01E−07		2.81E−07		2.52E−05		3.52E−05
	Heptachlor		2.74E−04(Mehran)			0.0001		1.25E−06		1.75E−06		1.25E−02		1.75E−02
	Aldrin		2.10E−05(Ilam)			0.0001		9.61E−08		1.34E−07		9.61E−04		1.34E−03
	heptachlor Epoxy isomer		5.40E−05(Chardavol)			0.0001		2.47E−07		3.45E−07		2.47E−03		3.45E−03
	Endrin ketone		3.2E−05 (Dehloran)			0.0002		1.46E−07		2.05E−07		7.32E−04		1.02E−03
	Endrin		4.26E−04 (Mehran)			0.0002		1.95E−06		2.72E−06		9.75E−03		1.36E−02
	D.D. E		2.20E−05 (Chardavol)			0.01		1.01E−07		1.41E−07		1.01E−05		1.41E−05
	Dieldrin		4.20E−05 (Mehran& Malekshahi)			0.0001		1.92E−07		2.68E−07		1.92E−03		2.68E−03
	D.D. D		5.90E−05 (Darehshahr)			0.01		2.70E−07		3.77E−07		2.70E−05		3.77E−05
Rice	Alpha-lindane		1.42E−04(Ivan)			0.008		2.14E−07		3.00E−07		2.67E−05		3.74E−05		1.69E−02		2.37E−02
	Lindane		4.40E−05(Ivan)			0.008		6.63E−08		9.28E−08		8.29E−06		1.16E−05
	Delta-lindane		1.27E−04 (Darehshahr)			0.008		1.91E−07		2.68E−07		2.39E−05		3.35E−05
	Heptachlor		2.22E−04 (Darehshahr)			0.0001		3.35E−07		4.68E−07		3.35E−03		4.68E−03
	Aldrin		3.50E−05 (Chardavol)			0.0001		5.27E−08		7.38E−08		5.27E−04		7.38E−04
	heptachlor Epoxy isomer		1.30E−05 (Ivan)			0.0001		1.96E−08		2.74E−08		1.96E−04		2.74E−04
	D.D. E		2.03E−04 (Sirvan)			0.01		3.06E−07		4.28E−07		3.06E−05		4.28E−05
	Dieldrin		4.25E−04 (Ivan)			0.0001		6.40E−07		8.97E−07		6.40E−03		8.97E−03
	Endrin		8.25E−04 (Darehshahr)			0.0002		1.24E−06		1.74E−06		6.22E−03		8.70E−03
	Endrin ketone		1.7E−05 (Ivan)			0.0002		2.56E−08		3.59E−08		1.28E−04		1.79E−04
	D.D. D		3.00E−05 (Ivan)			0.01		4.52E−08		6.33E−08		4.52E−06		6.33E−06
Tomato	Alpha-lindane		5.70E−05 (Sirvan)			0.008		1.95E−08		2.73E−08		2.44E−06		3.42E−06		7.21E−03		1.01E−02
	Lindane		1.05E−03 (Mehran)			0.008		3.61E−07		5.05E−07		4.51E−05		6.32E−05
	Delta-lindane		5.30E−05 (Malekshahi)			0.008		1.82E−08		2.54E−08		2.27E−06		3.18E−06
	Heptachlor		7.58E−04 (Abdanan)			0.0001		2.60E−07		3.63E−07		2.60E−03		3.63E−03
	Aldrin		4.90E−04 (Mehran)			0.0001		1.68E−07		2.35E−07		1.68E−03		2.35E−03
	heptachlor Epoxy isomer		4.89E−04 (Mehran)			0.0001		1.67E−07		2.34E−07		1.67E−03		2.34E−03
	D.D. E		2.00E−05 (Sirvan)			0.01		6.85E−09		9.59E−09		6.85E−07		9.59E−07
	D.D. D		1.19E−04 (Dehloran)			0.01		4.08E−08		5.71E−08		4.08E−06		5.71E−06
	Endrin aldehyde		3.1E−05 (Abdanan)			0.0002		1.06E−08		1.49E−08		5.31E−05		7.43E−05
	Endrin ketone		2.30E−04 (Abdanan)			0.0002		7.88E−08		1.10E−07		3.94E−04		5.51E−04
	Endrin		4.43E−04 (Ilam)			0.0002		1.52E−07		2.12E−07		7.59E−04		1.06E−03
	Methoxychlor		2.30E−05 (Abdanan)			0.1		7.88E−09		1.10E−08		7.88E−08		1.10E−07
Edible vegetable	Alpha-lindane		2.80E−05 (Dehloran)			0.008		5.18E−09		8.05E−09		6.47E−07		1.01E−06		3.06E−03		4.75E−03
	Lindane		8.35E−04 (Dehloran)			0.008		1.54E−07		2.40E−07		1.93E−05		3.00E−05
	Delta-lindane		1.07E−04 (Mehran)			0.008		1.98E−08		3.08E−08		2.47E−06		3.85E−06
	Heptachlor		8.15E−04 (Dehloran)			0.0001		1.51E−07		2.34E−07		1.51E−03		2.34E−03
	Aldrin		1.65E−04 (Darehshahr)			0.0001		3.05E−08		4.75E−08		3.05E−04		4.75E−04
	Endrin aldehyde		2.8E−05 (Dehloran)			0.0002		5.18E−09		8.05E−09		2.59E−05		4.03E−05
	Endrin		6.12E−04 (Mehran)			0.0002		1.13E−07		1.76E−07		5.66E−04		8.80E−04
	heptachlor Epoxy isomer		3.40E−04 (Dehloran)			0.0001		6.29E−08		9.78E−08		6.29E−04		9.78E−04
Stewed vegetable	Alpha-lindane		1.60E−05 (Darehshahr)			0.008		2.85E−09		4.09E−09		3.56E−07		5.11E−07		1.98E−03		2.86E−03
	Lindane		3.37E−04 (Dehloran)			0.008		6.00E−08		8.62E−08		7.50E−06		1.08E−05
	Delta-lindane		3.30E−05 (Chardavol)			0.008		5.88E−09		8.44E−09		7.35E−07		1.05E−06
	Heptachlor		5.97E−04 (Darehshahr)			0.0001		1.06E−07		1.53E−07		1.06E−03		1.53E−03
	Aldrin		1.77E−04 (Darehshahr)			0.0001		3.15E−08		4.53E−08		3.15E−04		4.53E−04
	heptachlor Epoxy isomer		2.32E−04 (Darehshahr)			0.0001		4.13E−08		5.93E−08		4.13E−04		5.93E−04
	Endrin ketone		2.9E−05 (Dehloran)			0.0002		5.16E−09		7.42E−09		2.58E−05		3.71E−05
	Endrin		1.81E−04 (Ilam)			0.0002		3.22E−08		4.63E−08		1.61E−04		2.31E−04
	D.D. D		3.20E−05 (Ilam)			0.01		5.70E−09		8.18E−09		5.70E−07		1.02E−06
Cantaloupe	Alpha-lindane		1.50E−05(Sirvan)			0.008		3.08E−09		4.32E−09		3.85E−07		5.39E−07		1.27E−03		1.78E−03
	Lindane		4.68E−04 (Darehshahr)			0.008		9.62E−08		1.35E−07		1.20E−05		1.68E−05
	Delta-lindane		9.40E−05 (Chardavol)			0.008		1.93E−08		2.70E−08		2.41E−06		3.38E−06
	Heptachlor		4.75E−04 (Darehshahr)			0.0001		9.76E−08		1.37E−07		9.76E−04		1.37E−03
	Aldrin		4.60E−05 (Dehloran)			0.0001		9.45E−09		1.32E−08		9.45E−05		1.32E−04
	heptachlor Epoxy isomer		2.50E−05 (Darehshahr)			0.0001		5.14E−09		7.19E−09		5.14E−05		7.19E−05
	Endrin ketone		6.7E−05 (Dehloran)			0.0002		1.38E−08		1.93E−08		6.88E−05		9.64E−05
	Endrin		5.9E−05 (Sirvan)			0.0002		1.21E−08		1.70E−08		6.06E−05		8.49E−05
	Methoxychlor		5.90E−05(Dehloran)			0.1		1.21E−08		1.70E−08		1.21E−07		1.70E−07
Watermelon	Alpha-lindane		2.70E−05 (Darehshahr)			0.008		7.40E−09		1.04E−08		9.25E−07		1.29E−06		3.59E−03		5.03E−03
	Lindane		1.03E−03 (Darehshahr)			0.008		2.83E−07		3.96E−07		3.53E−05		4.95E−05
	Delta-lindane		2.43E−04 (Chardavol)			0.008		6.66E−08		9.32E−08		8.32E−06		1.17E−05
	Heptachlor		8.41E−04 (Darehshahr)			0.0001		2.30E−07		3.23E−07		2.30E−03		3.23E−03
	Aldrin		4.90E−05 (Darehshahr)			0.0001		1.34E−08		1.88E−08		1.34E−04		1.88E−04
	heptachlor Epoxy isomer		7.20E−05 (Darehshahr)			0.0001		1.97E−08		2.76E−08		1.97E−04		2.76E−04
	Endrin aldehyde		2.7E−04 (Darehshahr)			0.0002		7.40E−09		1.04E−08		3.70E−05		5.18E−05
	Endrin ketone		8.9E−04(Darehshahr)			0.0002		2.44E−08		3.41E−08		1.22E−04		1.71E−04
	Endrin		5.50E−04 (Chardavol)			0.0002		1.51E−07		2.11E−07		7.53E−04		1.05E−03
	D.D. E		2.20E−05 (Chardavol)			0.01		6.03E−09		8.44E−09		6.03E−07		8.44E−07
Cucumber	Lindane		5.16E−04 (Chardavol)			0.008		1.06E−07		1.48E−07		1.33E−05		1.86E−05		1.82E−03		2.55E−03
	Delta-lindane		1.38E−04 (Chardavol)			0.008		2.84E−08		3.97E−08		3.54E−06		4.96E−06
	Heptachlor		4.02E−04 (Chardavol)			0.0001		8.26E−08		1.16E−07		8.26E−04		1.16E−03
	Aldrin		2.50E−05(Chardavol)			0.0001		5.14E−09		7.19E−09		5.14E−05		7.19E−05
	heptachlor Epoxy isomer		9.60E−05 (Dehloran)			0.0001		1.97E−08		2.76E−08		1.97E−04		2.76E−04
	Endrin		7.12E−04 (Chardavol)			0.0002		1.46E−07		2.05E−07		7.32E−04		1.02E−03
	D.D. E		2.60E−05 (Chardavol)			0.01		5.34E−09		7.48E−09		5.34E−07		7.48E−07
Melon	Alpha-lindane		2.40E−05 (Dehloran)			0.008		4.93E−09		6.90E−09		6.16E−07		8.63E−07		1.19E−03		1.75E−03
	Lindane		5.86E−04 (Darehshahr)			0.008		1.20E−07		1.69E−07		1.51E−05		2.11E−05
	Delta-lindane		1.62E−04 (Darehshahr)			0.008		3.33E−08		4.66E−08		4.16E−06		5.83E−06
	Heptachlor		4.44E−04 (Dehloran)			0.0001		9.12E−08		1.28E−07		9.12E−04		1.28E−03 3.94E−04
	Endrin		2.17E−04 (Darehshahr)			0.0002		4.46E−08		7.88E−08		2.23E−04
	Aldrin		1.70E−05 (Dehloran)			0.0001		3.49E−09		4.89E−09		3.49E−05		4.89E−05

**All acceptable daily intake (ADI) values used in this study were obtained from the European Food Safety Authority (EFSA) Pesticide Database and the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) toxicological evaluations.

Table 4S presents the residual concentration (μg/kg) of OCPs in wheat and tomato samples from various counties of Ilam province. As shown in Table 4S, wheat and tomato samples were collected from nine counties of Ilam province. Methoxychlor and Endosulfan pesticides were not detected in wheat and tomato samples from any of the counties, except for a minimal concentration (0.023 μg/kg) of Methoxychlor found in Abdanan tomato samples. Similarly, Endrin aldehyde was not detected in the wheat and tomato samples from any county except for Sirvan and Abdanan tomatoes, with minimal concentrations of 0.011 μg/kg and 0.031 μg/kg, respectively. The OCP residue analysis in Table 4S revealed that the wheat samples from Mehran had the highest concentration of Endrin pesticide, at 0.426 μg/kg and 0.413 µg/kg, followed by Heptachlor at 0.274 μg/kg. Therefore, Endrin and Heptachlor had the highest concentrations among all detected OCPs in wheat samples from various counties of Ilam province. The OCPs residue analysis in Table 4S showed that tomato samples from Mehran and Darehshahr contained the highest concentrations of lindane, at 1.052 μg/kg and 0.700 μg/kg, respectively. In addition, Heptachlor was detected in Abdanan and Sirvan tomato samples at concentrations of 0.758 μg/kg and 0.535 μg/kg, respectively. Other pesticides detected had concentrations ranging from 0.001 to 0.490 µg/kg. Similar to our study⁹, did not detect any OCPs residues in tomato samples, suggesting that this particular crop may not be subject to significant exposure to these pesticides⁹. In a study conducted in Togo, researchers analyzed 150 samples of ripe tomatoes, cabbage, and lettuce collected from various regions for the presence of 20 different OCPs. The results revealed that 100% analyzed samples were contaminated with one or more OCP. Cabbage samples had the highest number of pesticide residues above the MRLs, followed by tomato samples³.

Table 5S presents the residual concentrations (μg/kg) of OCPs detected in rice and corn agro-products samples from the counties of Ilam province. As shown in Table 5S, rice samples were collected from Ivan, Chardavol, Sirvan and Darehshahr counties, while corn samples were collected from Dehloran, Mehran and Darehshahr counties. Notably, none of the rice and corn samples analyzed for OCPs contained detectable levels of Endrin aldehyde, methoxychlor (except for corn from Mehran which contained 0.022 µg/kg), and Endosulfan. The findings in Table 5S reveal that the highest residual concentration of Endrin in rice samples was found in those cultivated in Darehshahr county (0.825 μg/kg), while Dieldrin and Endrin were detected in samples from Ivan County, with concentrations of 0.425 and 0.286 μg/kg, respectively. Notably, all these concentrations are lower than the permissible limit specified by the national standard. Table 5S shows that the highest residual concentrations of OCPs in corn samples were detected for D.D.E (0.252 μg/kg) and Heptachlor (0.192 μg/kg) in produce from Mehran county, and for Heptachlor (0.189 μg/kg) in samples from Darehshahr county. In the related study, authors assess the risk of OCPs presence in rice straw and grains from Punjab Province, Pakistan. The concentrations of OCPs (ng/g) were measured in total of 40 samples (20 samples each of rice straw and grains)²⁹. The findings indicated that the levels of OCPs (∑OCPs) in rice straw ranged from 3.63 to 39.40 ng/g, while in rice grains, the range was 2.72 to 49.89 ng/g. DDTs were found to be the most prevalent OCP isomers, followed by HCH and heptachlor²⁹. This pattern of OCPs was different from the current study being discussed. The authors concluded that the total concentration of OCPs (∑OCPs) in rice straw samples exceeded the MRLs set by Australian and Japanese standards²⁹. Another related study focused on determining the levels of OCPs in rice samples collected from Jiangsu Province, China. The OCPs analyzed included HCH and its isomers, DDT congeners, heptachlor, heptachlor epoxide, Aldrin, dieldrin, and Endrin¹⁰. The findings showed that the total concentrations of HCH (∑HCH) and DDT (∑DDT) in the rice samples ranged from 0 to 0.039 mg/kg and 0 to 0.053 mg/kg, respectively. Other OCPs, except for HCH and DDT, were not detected in the rice samples¹⁰. These results indicate that although some rice samples contained detectable levels of HCH and DDT, the concentrations were relatively low. The absence of the other five OCPs may suggest a decline in their usage or more effective control measures being implemented in the study area¹⁰. In a study conducted by²⁸, the researchers aimed to evaluate the contamination levels of OCPs in cereal crops, specifically wheat and rice, collected from the Gujranwala division in Punjab Province, Pakistan. A total of 28 samples were analyzed. The results showed that the total concentrations of OCPs (∑OCPs) ranged between 0.55 and 15.2 ng/g for rice and wheat samples, respectively. Among the detected OCPs, DDTs were found to be the most prevalent²⁸. In a similar study, the researchers analyzed the residual levels of organochlorine pesticides (OCPs) in wheat and rice samples cultivated across river Chenab, Pakistan. The results showed that the levels of OCPs detected in wheat ranged from 1.78 to 12.46 ng/g, while in rice, the range was 4.92 to 18.19 ng/g. Among the detected OCPs, DDD, DDE, and HCH were the most prevalent in both wheat and rice samples³⁷. Therefore, continuous monitoring of OCP residue levels in food crops is crucial to protect consumer health and ensure food safety. Moreover, implementing sustainable agricultural practices and proper pesticide management strategies can help minimize the risk of OCP contamination in agricultural products.

Table 6S presents the residual concentrations (in µg/kg) of OCPs detected in edible and stewed vegetable samples collected from five counties of Ilam province: Ilam, Dehloran, Darehshahr, Mehran and Chardavol. The analyses revealed that six of the fourteen OCPs, namely D.D.D, D.D.E, Dieldrin, Endrin ketone, methoxychlor and Endosulfan, were not detected in the edible vegetable samples collected from the different counties of Ilam province. Similarly, stewed vegetable samples from all counties were found to be free of the OCPs methoxychlor, Endrin aldehyde, D.D.E, Dieldrin, and Endosulfan, as they were not detected during the analyses. Based on the examination conducted in the samples of edible vegetables, the highest residual concentrations of OCPs were detected for lindane (0.835 μg/kg) and heptachlor (0.815 μg/kg) in produce from Dehloran city. Additionally, Endrin pesticide residue in edible vegetables from Mehran city was detected at a concentration of 0.612 μg/kg. Table 5S illustrates that the residual concentrations of lindane, Endrin, and heptachlor pesticides in edible vegetable samples from the other counties ranged from 0.2 to 0.4 μg/kg, while the remaining OCPs were detected at concentrations of 0.0 to 0.2 μg/kg. Table 6S shows that the highest residual concentration of heptachlor in vegetable stewed samples was detected in produce from Darehshahr and Mehran counties, with 0.597 and 0.369 μg/kg, respectively, followed by lindane in samples from Dehloran city, with 0.337 μg/kg. Other pesticides were also detected at various concentrations. The findings of this study align with the results of¹⁶ which investigated pesticide residues in vegetables in Jilin Province and reported detectable OCP residues that were within the permissible standard limit. They concluded that Leafy vegetables were found to contain the highest concentration of pesticides, possibly due to their larger surface area for pesticide absorption¹⁶. In a study investigating pesticide residues in vegetables from Haryana, India, researchers found that about one-third of the samples had detectable pesticide residues. Alarmingly, banned or withdrawn pesticides, including DDT and Endosulfan, were also detected, indicating a need for stricter enforcement of agricultural regulations. Of the analyzed samples, around 40% had pesticide residues within the MRLs, while 16% exceeded the established MRLs, emphasizing the importance of ongoing monitoring to ensure food safety and consumer well-being⁴. The elevated pesticide concentrations detected in vegetables compared to other food products can be attributed to several factors. Vegetables are often directly exposed to pesticides during cultivation, including foliar sprays, which can result in higher residue accumulation on edible parts^15,38. Additionally, vegetables generally have a higher surface area-to-mass ratio than fruits or grains, which may enhance pesticide retention^3,16. The frequency and timing of pesticide applications, crop type, and local agricultural practices in the region may also contribute to the observed higher residue levels^2,7. These findings are consistent with previous studies that report higher pesticide residues in leafy and surface-exposed vegetables due to their direct exposure and growth characteristics⁴.

Table 7S displays the residual concentrations (μg/kg) of 14 OCPs in cantaloupe, watermelon, cucumber, and melon samples from various counties in Ilam province. In Table 7S, it can be seen that five OCPs, namely Dieldrin, D.D.D., Methoxychlor (except for cantaloupe in Dehloran and Sirvan with concentration of 0.059 and 0.014 µg/kg, respectively), Endosulfan, and Endrin aldehyde (except for watermelon in Chardavol and Darehshahr with concentration of 0.016 and 0.027 µg/kg, respectively) were not detected in cantaloupe, watermelon, cucumber, and melon samples from various counties in Ilam province. In the measurements of pesticides in the cantaloupe cultivated in the counties of Ilam province as shown in Table 7S, the highest OCPs detected in cantaloupe cultivated in Darehshahr city were heptachlor and lindane, with concentrations of 0.475 and 0.468 μg/kg, respectively. The third highest concentration was found in the cantaloupe from Chardavol, with a heptachlor concentration of 0.285 μg/kg. Furthermore, it is noteworthy that no D.D.E. pesticides were detected in any of the cantaloupe samples from the counties. Nevertheless, the concentrations of other pesticides detected were not significant and were lower than the recommended national standard of Iran. The highest concentrations of OCPs in the watermelon samples from Darehshahr and Chardavol counties were 1.032 μg/kg and 0.834 μg/kg for lindane, respectively, followed by heptachlor in Chardavol watermelon samples with a concentration of 0.841 μg/kg (As demonstrated in Table 7S). The other evaluated OCPs had concentrations ranging from 0.001 to 0.250 μg/kg. The residual concentration (μg/kg) of OCPs in cucumber samples from Dehloran, Darehshahr, and Chardavol counties in Ilam province was measured and reported in Table 7S. In the analysis of the cucumber samples from Ilam province, the highest concentrations of OCPs were found for Endrin, lindane, and heptachlor in Chardavol city, with concentrations of 0.712, 0.516, and 0.402 μg/kg, respectively. Other OCPs were also detected in the cucumber samples, but their concentrations were insignificant and below the national standard. A study conducted by Mansour, Belal, et al. in 2009³⁹ investigated pesticide residue levels in cucumber samples from three different farming production types—conventional, greenhouse, and organic—in Giza governorate, Egypt. A total of 216 kg of cucumber samples were collected and analyzed for OCPs residues. The results revealed that some OCP residues, including hexachlorobenzene (HCB), heptachlor, Aldrin, Endrin, dieldrin, and o,p'-DDT, were detected in several samples at concentrations exceeding their MRLs³⁹. Additionally, lindane was found in 33.3% of conventional, 50.0% of greenhouse, and 25.0% of organic cucumber samples. The authors observed variations in pesticide contamination levels among the three cucumber types across different seasons³⁹. A related study conducted in the Asir region of Saudi Arabia examined 211 vegetable samples across 10 different commodities for the presence of 80 different pesticides. The authors found that lettuce, cauliflower, and carrot samples were free of detectable pesticide residues, while 145 samples (68.7%) had residues at or below the MRL, and 44 samples (20.9%) exceeded the MRL³⁰. Among the vegetables, chili pepper and cucumber had the highest number of samples with MRL exceedances³⁰.

Table 7S shows the residual concentration (μg/kg) of OCPs in melon samples from Darehshahr and Dehloran counties of Ilam province. Out of the fourteen OCPs investigated in melon samples from Dehloran and Darehshahr, seven OCPs, namely D.D.E., Dieldrin, D.D.D., Methoxychlor, Endosulfan, Endrin aldehyde, and Endrin ketone, were not detected in the samples from either of the counties. As demonstrated in Table 7S, the highest concentration of OCPs in melon samples from Darehshahr and Dehloran were lindane (0.586 μg/kg and 0.421 μg/kg, respectively) and heptachlor (0.444 μg/kg in melon from Dehloran), with all concentrations falling between 0.3 and 0.6 μg/kg, which is below the national standard of Iran. Several studies on the occurrence of OCPs residues in African environment have revealed that certain OCPs tend to persist in various environmental matrices (freshwater systems, sediments, soil, vegetables and various food substrates). α-HCH, β-HCH, DDTs, and Endosulfan have been identified as the most persistent OCP residues in Africa¹⁸. In a study conducted in the agricultural lands of Dalaki and Shabankare areas in Bushehr province, southern Iran, researchers analyzed topsoil samples for the presence of various OCPs, specifically HCH, heptachlor, DDT and CHL. The results showed that the highest to lowest concentration of pesticides in both areas followed the trend of DDT > CHL > HCH¹⁷. In another study was conducted to measure the concentration levels of OCPs residues in soil samples collected from a lowland paddy field in Kelantan, Malaysia. Out of ten OCPs analyzed, six were detected in the soil samples, including hexachlorocyclohexane isomers (α, β, γ, δ), 4,4-dichlorodiphenyltrichloroethane (4,4-DDT), and Endosulfan sulfate. The concentration levels of these detected OCPs were quantified in µg/kg. The results showed varying concentrations of the detected OCP residues in the soil samples. The presence of these POPs in the paddy field soils highlights the need for regular monitoring and assessment of environmental contamination by OCPs, especially in agricultural areas⁴⁰. Our findings are consistent with recent studies from Iran and other countries indicating that, although OCP residues are generally below regulatory limits, their environmental persistence continues to result in detectable levels in fruits, vegetables, and cereals. Given the findings of this studies and the fact that these OCPs have been banned, their continued presence in topsoil, albeit in trace concentrations, demonstrates the need for further investigation of their potential accumulation in agricultural products. This is essential to ensure food safety, protect human health, and maintain the overall quality of the environment. This information can help guide policies and practices aimed at promoting sustainable agriculture and ensuring food safety in Iran.

Human health risk evaluation

Human health risk assessment was conducted using the maximum detected concentrations of OCP residues measured in the various agricultural crops (lentil, chickpea, corn, wheat, rice, tomato, edible vegetables, stewed vegetables, cantaloupe, watermelon, cucumber, and melon) collected from different counties. Based on these concentrations, the EDI values were calculated, and the corresponding THQ values for both child and adult consumers are presented in Table 3. As shown in Table 3, variations in OCP concentrations among crop types resulted in THQ values lower than 1 for all evaluated crops in both population groups. The individual HQ values for all agricultural products included in the study are summarized in Table 3. Furthermore, the sum of all HQ values, calculated as the HI, remained below the critical threshold of 1 for both adults and children, indicating no significant non-carcinogenic health risk, as also illustrated in Fig. 3. The HI values for adult consumers were calculated for each crop and were as follows: lentil (7.33E−04), chickpea (1.35E−03), corn (6.50E−05), wheat (2.85E−02), rice (1.69E−02), tomato (7.21E−03), edible vegetables (3.06E−03), stewed vegetables (1.98E−03), cantaloupe (1.27E−03), watermelon (3.59E−03), cucumber (1.82E−03), and melon (1.19E−03). Similarly, the HI values for child consumers were 1.03E−03, 1.89E−03, 7.45E−05, 3.99E−02, 2.37E−02, 1.01E−02, 4.75E−03, 2.86E−03, 1.78E−03, 5.03E−03, 2.55E−03, and 1.75E−03, respectively. In a similar study, researchers estimated the daily intake (EDI) of total OCPs (∑OCPs) through rice and wheat consumption, reporting 39 ng/kg/day for rice and 40 ng/kg/day for wheat. Using the 95th percentile concentrations of OCPs, they calculated the corresponding health risks (HRs), which are used to evaluate the potential adverse effects associated with chronic exposure to these pesticide residues. Their findings showed that the HRs for most of the OCPs detected in rice and wheat exceeded the acceptable safety threshold. This suggests a potentially severe health risk for the population in that study area due to consumption of contaminated cereal crops²⁸. Consistent with the findings of the present study⁴¹, reported that the median HI values for DDTs and HCHs among child, adolescent, adult, and senior male and female consumers in Nanjing were all below 1, indicating no significant non-carcinogenic health risk from exposure to these pesticides. In their HRA, the researchers also found no meaningful non-cancer risk for local residents; however, the estimated cancer risk ranged from 1.0E−06 to 1.0E−04. Although this range exceeded the acceptable cancer risk threshold, it remained below the priority risk level, suggesting the need for continued monitoring and risk management interventions⁴¹. In a similar study, the authors evaluated the health risks associated with OCPs detected in wheat and rice samples. Their findings showed that both HQ and HI values exceeded 1 for several OCPs, indicating a potential non-carcinogenic risk from exposure to these pesticides through consumption of contaminated wheat and rice. The researchers further estimated cancer risk using the USEPA’s acceptable carcinogenic risk range, in which a tolerable risk level is defined as less than 10⁻⁶ (one in a million). However, in their assessment, the cancer risk values calculated for DDD, DDE, HCH, CT, and HC were higher than this acceptable threshold. These results suggest a potential carcinogenic risk to consumers of the affected cereal crops. Based on these findings, the study emphasized the urgent need to establish comprehensive assessment, monitoring, and reporting programs to reduce pesticide contamination and human exposure in Pakistan³⁷. The findings of this study indicate that pesticide contamination does not pose a major human health concern, as all detected residues were below the EU MRLs. It is also important to note that the samples were collected directly from farms, where residue levels are typically lower than those found in samples taken from packing houses due to potential degradation of pesticides during the interval between harvesting and distribution. Nevertheless, continuous monitoring remains essential to ensure ongoing food safety for consumers. In addition, post-harvest activities such as storage, washing, peeling, and cooking can substantially reduce pesticide residue levels in agricultural products, as previously demonstrated by Kaushik, 2009³⁸. Although the calculated HI values for all age groups (adult and children) were below 1 for all crops, indicating no significant non-cancer risk, it is important to note that several detected OCPs (including lindane, heptachlor, Aldrin, Endrin, and DDT derivatives) are classified as possible or probable carcinogens. For example, heptachlor and dieldrin (detected in several samples) are classified as Group 2A (probably carcinogenic), while Lindane, Aldrin, Endrin, and DDT derivatives fall under Group 2B (possibly carcinogenic)²⁵. Therefore, long-term exposure, even at low concentrations, may carry carcinogenic relevance, especially for children and populations with high consumption of local agricultural crops. This emphasizes the need for continuous monitoring and efforts to minimize OCP contamination in food crops.

Fig. 3.

HI estimation in the children and adults due to different agricultural crops consumption.

Limitation section

Despite its strengths, this study is not without limitations. A major limitation of this study is the restricted sample size for several crop categories, which reduces the overall representativeness of the dataset and limits the statistical confidence of the dietary exposure estimates. The sampling was limited to a single province and one harvesting season, which may not capture seasonal or geographical variations in pesticide use and residue accumulation. Although 61 samples from 12 agricultural crops were collected across 10 counties in Ilam Province, the number of samples for certain crops (such as cucumber, cantaloupe, watermelon, and melon) was limited to a single sample per county due to seasonal availability, production variability, and logistical constraints. In some cases, only one sample was obtained from specific counties, further limiting spatial coverage. Consequently, although the results offer important preliminary insights into OCP contamination patterns, they should be interpreted with caution, as the findings cannot be fully generalized to the broader regional production system. The study focused only on OCPs, while other classes of pesticides (such as organophosphates, carbamates, and neonicotinoids) were not analyzed, although they may also pose potential risks.

Future monitoring programs should therefore incorporate substantially larger and more representative sample sizes for each crop, expand sampling across additional geographic areas, and include multiple sampling periods throughout the growing season to enhance both representativeness and reliability. While the analytical method used in this study was rigorously validated through calibration, recovery, and precision assessments, future investigations would benefit from inter-laboratory validation to further strengthen methodological robustness and ensure consistency across different analytical settings. The assessment was limited to non-carcinogenic health risks; future studies should also consider carcinogenic and cumulative risks from multi-pesticide exposures.

Conclusion and suggestions

This study presents a comprehensive investigation on the residual concentrations of fourteen OCPs in twelve agricultural crops (lentils, chickpea, corn, wheat, rice, tomato, edible vegetable, stewed vegetable, melon, watermelon, cucumber and melon) produced in various counties of Ilam province, Iran. The practical goal of this research is to provide reliable baseline data on OCP residues in locally grown agricultural products to support food safety monitoring, inform regulatory decision-making, and promote safer pesticide management practices in the region. This work offers new insights into the current status of pesticide exposure in southwestern Iran. Notably, the detected residues of all OCPs in the examined crops were below the MRL of 50 μg/kg established by the Iranian national standard and FAO/WHO guidelines. This study is the first to report OCP residues in lentil and chickpea crops in Iran, thereby filling an important gap in the literature and offering essential baseline data for future food safety surveillance programs. The lack of previous research highlights the need for continued investigation into the presence and potential health risks of pesticide residues in these widely consumed crops. The results of the HRA showed that the HI values for both adult and child consumers were below 1 for all crop types, indicating that exposure to OCP residues does not pose a significant non-carcinogenic health risk. Although the HRA suggests that consumers are not exposed to high-risk levels, the detection of OCPs in agricultural crops underscores the importance of strict monitoring and appropriate management of pesticide application practices to prevent potential health hazards. While minor variations in OCP concentrations were observed among counties, these differences were not meaningful at the population level and were consistent with the uniformly low HI values (HI < 1). Despite the negligible non-carcinogenic risks, the presence of OCPs classified as possible or probable carcinogens highlights the necessity for continued monitoring and the implementation of effective control strategies to reduce potential long-term cancer risks. Although the current findings indicate that the measured OCP levels do not pose an immediate dietary health risk for adult or child consumers, these conclusions should be interpreted with caution due to the limited sample size and the uneven distribution of crop samples across the region. The results, showing that all HQ and HI values were below 1, further underscore the relatively low risk associated with the consumption of these crops and provide important baseline information for policymakers, regulatory agencies, and agricultural stakeholders. To ensure a more robust and regionally representative assessment of dietary exposure, future studies should adopt broader and more systematic sampling frameworks. Consequently, prioritizing continuous monitoring of pesticide residues in food products and evaluating their potential health impacts is essential to ensure effective consumer protection against the harmful effects of pesticide contamination.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

CRediT authorship contribution statementZahra Noorimotlagh: Methodology, Validation, Formal analysis, Investigation, data curation, conceptualization, Methodology, Writing- review & editing. Neemat Jaafarzadeh: Methodology, Validation, Formal analysis, Methodology, Writing- review & editing. Ali Amarloei: Conceptualization, Methodology, Validation, Resources, Project administration.Seyyed Abbas Mirzaee: Conceptualization, Methodology, Validation, Resources, Writing-original draft, Writing-review & editing.

Funding

This study has been supported by the Agriculture Organization of Ilam Province, Iran and Ilam University of Medical Sciences (IUMS) (Grant Number: 729355: 1398-12-14 with ethical Code of IR.MEDILAM.REC.1401.028 from Ilam University of Medical Sciences (IUMS)). We gratefully acknowledge their assistance.

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.