Human Health Risk of Organochlorine Pesticides in Foods Grown in Nigeria

Determination of pesticide residue content in fruits and vegetables from Lagos, Nigeria

Developing countries like Nigeria are increasingly employing pesticides to boost the productivity of their agriculture and food supply, despite the fact that doing so poses a health risk to the general populace. The purpose of this study was to assess pesticide residue levels in Lagos, Nigeria. A total of 18 samples from three neighbourhood markets were collected, and they were then examined for the presence of organochlorine (Endosulfan I, Pentachlorophenol, Heptachlor epoxide, and Endosulfan II) and organophosphate (Dichlorvos, Dimethoate, Phorate, and methyl parathion) residues. During the pre-treatment, the multi-residue Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS citrate) method with the addition of acetonitrile was used, and then samples were analysed using GC-MS. All of the samples contained dichlorvos, but the orange sample's concentration was below the limit of quantification, making quantification impossible. Dimethoate concentrations were below MRLs except waterleaf sample. With a concentration of 0.043 μg/mL, Waterleaf had the highest quantity of dimethoate in the sample. The findings of this study indicate that in order to safeguard the health of consumers, it is necessary to closely monitor organochlorine and organophosphate use nationwide, along with other related pesticides, and to test for pesticide residues in food products.

Concentration levels and risk assessment of organochlorine and organophosphate pesticide residue in selected cereals and legumes sold in Anambra State, south-eastern Nigeria

The levels of organochlorine and organophosphate pesticide residues in selected cereal crops (beans, cowpea, millet, maize, sorghum, and rice) purchased from major markets in Anambra, south-eastern Nigeria, were assessed and compared with established MRLs. The QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used for extraction and clean-up of pesticide residues. Thereafter detection and quantification were done using GC/MS. The result reveals that the analysed grain samples contained some organochlorine pesticides and organophosphates. The organochlorine was most dominant followed by the organophosphates. Organochlorine pesticide residues varied from 0.048 to 0.298 mg/kg in beans, BDL to 0.398 mg/kg in cowpea, 0.018–0.337 mg/kg in maize, 0.023–0.375 mg/kg in millet, 0.058–0.415 mg/kg in sorghum and 0.045–0.442 mg/kg in rice while organophosphate pesticide residue varied from BDL to 0.315 mg/kg in beans, BDL to 0.113 mg/kg in cowpea, BDL to 0.228 mg/kg in maize, BDL to 0.253 mg/kg in millet, BDL to 0.218 mg/kg in sorghum and BDL to 2.1 35 mg/kg in rice. Highest concentration of endosulphan II (0.442 mg/kg) was detected in rice, followed by aldrin (0.415 mg kg−1) in sorghum and endosulphan II (0.40 mg/kg) in sorghum. The pesticide toxicity index (PTI) was above one (1), whereas health index (HI) was less than one (1) and cancer risk were within USEPA reference guideline for crops indicating children will have greater health effect than adults. Hence, strict monitoring and control of pesticide residues in agricultural products is advocated.

Concentration evaluation and risk assessment of pesticide residues in selected vegetables sold in major markets of Port Harcourt South-South Nigeria

Concentration levels and health risk assessment of residues of organochlorine and organophosphate pesticides in four commonly vegetables (Cucumber, carrot, cabbage, and eggplant) collected from major markets of Port Harcourt city, South-south Nigeria were assessed. The collected samples were analysed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method by gas chromatography coupled with Electron Capture Detector (ECD). Pesticide concentrations were compared with UK/EU maximum residual limits (MRLs). Health risk estimates were analysed using estimated daily intake (EDI), hazard quotient (HQ), and hazard ratio (HR) for children (16.7 kg) and adults (60 kg) weight groups. The results of this study showed that 80% of the vegetable samples contained detectable pesticide residues, of which 70% had residues that exceeded MRLs while 20% had residues below detectable levels. The highest concentrations of HCH residues are present in cabbage with a concentration of 0.25 ± 0.15 mg/kg for α-HCH while the least are present in eggplant with concentration of 0.038 ± 0.025 mg/kg in lindane. Pirimophos-methyl was detected in cucumber at 0.017 mg/kg while parathion and isofenfos was detected only in eggplants at concentration of 0.042 mg/kg and 0.022 mg/kg respectively. Concentrations of parathion, chlorpyrifos, and pirimophos-methyl residues were lower than MRLs in all the detected vegetable samples analysed. Non-carcinogenic health risk estimates for the children consumer groups showed that mevinfos, p, pʹ DDD, aldrin, and heptachlor epoxide detected in eggplant, carrot, and cabbage had HQ > 1. While for adults, only p, pʹ DDD and heptachlor epoxide revealed non-carcinogenic effect in cabbage. Risk was highest for child consumers. However, most of the pesticide residues were less than 1 for the HQs value which is indicative of insignificant health risk. Human risk estimations for the carcinogenic health effect for the studied vegetables showed that lindane and delta HCH could pose carcinogenic health risks to adult, while aldrin, dieldrin, heptachlor, α HCH, β HCH, delta HCH, and heptachlor epoxide could pose carcinogenic health risks to children. The HRI values in some of the detected residues indicate that the cancer benchmark concentrations exceeded the EDI for the respective organochlorine pesticide in the vegetable samples, thus raising serious concerns of possible carcinogenicity. Non carcinogenic and carcinogenic risk assessment of organochlorine pesticide residues in the studied vegetable indicates health threat. Hence, strict monitoring and control of pesticide residues in agricultural products is being suggested, to protect consumers, especially the children who are vulnerable to the adverse effects of pesticides.

A Comprehensive Review of Pesticide Residues in Peppers

Pesticides are chemicals that are used to control pests such as insects, fungi, and weeds. Pesticide residues can remain on crops after application. Peppers are popular and versatile foods that are valued for their flavor, nutrition, and medicinal properties. The consumption of raw or fresh peppers (bell and chili) can have important health benefits due to their high levels of vitamins, minerals, and antioxidants. Therefore, it is crucial to consider factors such as pesticide use and preparation methods to fully realize these benefits. Ensuring that the levels of pesticide residues in peppers are not harmful to human health requires rigorous and continuous monitoring. Several analytical methods, such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and nuclear magnetic resonance spectroscopy (NMR), can detect and quantify pesticide residues in peppers. The choice of analytical method depends on the specific pesticide, that is being tested for and the type of sample being analyzed. The sample preparation method usually involves several processes. This includes extraction, which is used to separate the pesticides from the pepper matrix, and cleanup, which removes any interfering substances that could affect the accuracy of the analysis. Regulatory agencies or food safety organizations typically monitor pesticide residues in peppers by stipulating maximum residue limits (MRLs). Herein, we discuss various sample preparation, cleanup, and analytical techniques, as well as the dissipation patterns and application of monitoring strategies for analyzing pesticides in peppers to help safeguard against potential human health risks. From the authors' perspective, several challenges and limitations exist in the analytical approach to monitoring pesticide residues in peppers. These include the complexity of the matrix, the limited sensitivity of some analytical methods, cost and time, a lack of standard methods, and limited sample size. Furthermore, developing new analytical methods, using machine learning and artificial intelligence, promoting sustainable and organic growing practices, improving sample preparation methods, and increasing standardization could assist efficiently in analyzing pesticide residues in peppers.

Bioaccumulation of Organophosphorus (OPs) and Carbamate (CBs) Residues in Cultured Pangas Catfish (Pangasius pangasius) and Health Risk Assessment

In the present study, the presence of organophosphorus (OPs) and carbamates (CBs) residues in the pond water and cultured Pangas catfish (Pangasius pangasius) samples collected from Comilla and Mymensingh areas were detected and assessed for their potential health risks. A total of 100 samples from each category were analysed among which 17% of the pond water samples and 9% of the fish samples were detected contaminated with OP and CB residues. The pond water and fish samples were extracted by liquid-liquid extraction (LLE), quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction, and ultrasonic extraction, respectively, and analysed through gas chromatography tandem mass spectrometry (GC-MS/MS). Among the detected OPs, Dursban (chlorpyrifos) and dichlorvos were detected, while among CB pesticides, carbofuran and sevin (Carbaryl) were detected in fish muscle samples. The detected OP and CB residual levels were below than the maximum residue limits (MRLs). The risk assessment study indicated no potential health risks. However, the level of compliance should be maintained through proper monitoring and controlling the overuse of pesticides in agricultural fields for public health safety.

Human exposure to organochlorine pesticides in vegetables from major cities in south-south Nigeria

Contamination of vegetables with organochlorine pesticides (OCPs) during cultivation could affect their nutritional value and also results in adverse health effects to consumers. Thus, this study evaluates human exposure to OCPs in vegetables from major cities in south-south Nigeria. A total of eighty vegetables consisting of Vernonia amygdalina, Telfairia occidentalis, Desmodium intortum cv and Talinum triangulare obtained from four major cities (Warri, Benin, Yenagoa and Port-Harcourt) in south-south Nigeria were analysed for OCPs using a gas chromatograph coupled with a mass selective detector. The results showed that the mean concentration of ∑20 OCPs in the vegetables ranged from 11.6 to 37.7 ng g^-1 fresh wt for Vernonia amygdalina, 2.48-37.0 ng g^-1 fresh wt for Telfairia occidentalis, 7.63-54.2 ng g^-1 fresh wt for Desmodium intortum cv and 27.3-57.3 ng g^-1 fresh wt for Talinum triangulare. The concentrations of OCPs were generally lower than their respective Maximum Residue Limits (MRLs). The EDI values of the ∑20 OCPs in the vegetables ranged from 141 to 464 ng kg^-1 bw day^-1 for children and 26.5-87.0 ng kg^-1 bw day^-1 for adults. The EDI of ∑Drins, ∑Chlordanes and ∑DDTs for the vegetables were below their respective acceptable EDI values set by FAO/WHO Joint Meeting on Pesticide Residue. The hazard index values for children and adults were generally <1 suggesting that there is no potential non-carcinogenic risk for children and adults consuming the vegetables. The total cancer risk values were above 1 × 10^-6 and indicated that children and adults have moderate and low carcinogenic risks respectively from ingestion of these vegetables. The isomeric ratios and principal component analysis result showed that OCPs in these vegetables originated from both historical and recent usage in vegetable cultivation.

Risk Assessment of Organochlorine Pesticide Residue in Phaseolus vulgaris Purchased in Igbara-oke, Ondo State, Nigeria

&lt;b&gt;Background and Objective:&lt;/b&gt; Preservation of agricultural products remains a hallmark of all farmers as a result, both pesticides and herbicides are being applied during planting and after harvesting with the sole aim of maximizing profits. Research had shown the various degree of toxicity of organochlorine pesticides residues, the objective of the research was to identify the organochlorine pesticide residues, analyze their risk assessment vis-a-vis, Hazard Index (HI), Estimate Dietary Intake (EDI), Target Hazard Quotient (THQ) and compare the results with Acceptable Dietary Intake (ADI), Reference dose standard (Rfd) and Maximum Residue Limit (MRL) and characterized the identified organochlorine pesticides residue for their toxicological properties. &lt;b&gt;Materials and Methods:&lt;/b&gt; &lt;i&gt;Phaseolus vulgaris&lt;/i&gt; were purchased in a local market in Igbara -Oke, Ondo state Nigeria, the sample was powdered using a grinder (Sumeet CM/L 2128945) and solid phase extraction techniques were employed, the extract was subjected to fractionation into two fractions of aliphatic hydrocarbons and the pesticides. The pesticide extract was subjected to characterization using gas chromatography-mass spectrophotometer. &lt;b&gt;Results:&lt;/b&gt; Total 4 organochlorine pesticide residues were identified and the contaminant rates (mg kg&lt;sup&gt;1&lt;/sup&gt;) were less than 1. Furthermore, EDI values were lower than the ADI, MRL, also, the THQ values were less than 1, an indication that the &lt;i&gt;Phaseolus vulgaris&lt;/i&gt; was safe for consumption. &lt;b&gt;Conclusion:&lt;/b&gt; The research had shown no toxicity of the &lt;i&gt;Phaseolus vulgaris&lt;/i&gt; purchased from the local market and it shows compliance by the local farmers on the application of pesticides to the food crop by obeying the recommended dose.

Contamination of Foods from Cameroon with Residues of 20 Halogenated Pesticides, and Health Risk of Adult Human Dietary Exposure

(1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no information on the health risk of consumers from exposure to their residues in foods. (2) Methods: Residues of 20 halogenated pesticides were determined in 11 agricultural products collected in the 3 largest cities of Cameroon using QuEChERS extraction and gas chromatography with electron capture detector (GC-ECD), and health risk from dietary exposure was assessed. (3) Results: Organochlorines pesticides aldrin, p,p'-dichlorodiphenyl-trichloroethane (DDT) and β-hexachlorocyclohexane (β-HCH) found in 85.0%, 81.9% and 72.5% of samples, respectively, were the most frequently detected. The highest average concentrations of residues were 1.12, 0.74 and 0.39 mg/kg for methoxychlor, alachlor and β-HCH, respectively, found in chilli pepper. Chili pepper (58.9%), cowpea (56.8%), black beans (56.5%) and kidney beans (54.0%) exhibited the highest residue occurrences. Levels above the European Union maximum residue limits (MRLs) were found for all the 20 pesticides, in 40.1% of the positive analyses, and the food samples contained 14 pesticides banned in Cameroon. Chronic, acute, cumulative and carcinogenic risk assessments revealed that lifetime consumption of maize, black beans, kidney beans, groundnuts and chili pepper contaminated with aldrin, dieldrin, endrin, HCB, heptachlor, o,p'-DDT, p,p'-DDD, p,p'-DDT, p,p'-DDE and β-HCH, could pose health risks. (4) Conclusion: These results show that there is an urgent need of pesticide usage regulation, effective application of pesticide bans and management of obsolete pesticide stocks in Cameroon.

Cabbage Production in West Africa and IPM with a Focus on Plant-Based Extracts and a Complementary Worldwide Vision

In urban and peri-urban areas in West Africa, the cabbage Brassica oleracea L. (Brassicaceae) is protected using repeated high doses of synthetic insecticides. After a brief description of available IPM components, this paper presents a literature review focused on the botanical extracts that have been experimented with at the laboratory or in the field in West Africa against major cabbage pests. The literature reviewed mentions 19 plant species from 12 families used for cabbage protection in the subregion. The species most used are Azadirachta indica, Capsicum frutescens, Ocimum gratissimum and Ricinus communis. An overview of the world literature showed that a total of 13 plant species belonging to 8 families used to control cabbage pests are reported from the rest of Africa, and 140 plant species belonging to 43 families from the rest of the world. The most commonly used and tested plant species against insect pests in the three geographical areas considered is A. indica.

Determination of organochlorine pesticides in human umbilical cord and association with orofacial clefts in offspring

Studies based on questionnaires suggested that maternal exposure to pesticides increases the risk for orofacial clefts (OFCs). However, whether organochlorine pesticides (OCPs) exposure in vivo affects the occurrence of OFCs remains unclear. The aims of this study are to investigate the association of OCP exposure with the risk of OFCs by examining the concentrations of OCPs in human umbilical cords, and investigate the potential dietary sources of OCPs in umbilical cord tissues. A case-control study consisting of 89 OFC cases and 129 nonmalformed controls with available tissues of umbilical cord was conducted. Concentrations of twenty specific OCPs were determined in the umbilical cord by gas chromatograph-mass spectrometry, and seven OCPs with detection rate larger than 50% were included in analyses. The individual effect and joint effect of multiple OCPs in umbilical cords on the risk for OFCs were investigated using multivariate logistic models and Bayesian Kernel Machine Regression (BKMR). No difference was found in the median levels of ΣOCPs between cases (1.04 ng/g) and controls (1.03 ng/g). No significant associations were observed between levels of OCPs in umbilical cords and risk for OFCs in either multivariate logistic models or BKMR models. Maternal consumptions of beans or bean products were positively correlated with levels of β-hexachlorocyclohexane, heptachlor epoxide, p,p'-DDE, and ∑OCPs in umbilical cord, respectively. In conclusion, we didn't find the association between in utero exposure to OCPs and the risk for OFCs. Maternal consumptions of beans or bean products may be a source of OCPs exposure.

Occurrence, distribution, and risk of organochlorine pesticides in food and greenness assessment of method

Organochlorine pesticides (OCPs) have been used globally to boost food production. Although banned, due to their prolonged toxic effects but their residue still impacts the quality of primary and processed agricultural products. This study assesses the levels of residual OCPs (α,β,δ-HCH, heptachlor, heptachlor epoxide, chlordane, methoxychlor, aldrin, dieldrin, endrin, endrin aldehyde, endrin ketone, endosulfan, endosulfan sulfate, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)) in food commonly consumed in Lagos and Ibadan, Southwest, Nigeria. Health risk associated with human exposure via food intake was evaluated with a statistical predictive model. About 248 composite food samples from 8 categories were analyzed in Lagos and Ibadan. Sample extraction and clean-up were by QueChERS method and extracts injected into GC-μECD. ƩDDT concentration was highest in meat products, aquatic foods, dairy products, edible oils, fruits, and cereals, while ƩHCHs were highest in chicken eggs and vegetables. ƩOCP concentrations (ng/g) in food categories were 6.09±1.6-6.85±0.9 (meat), 5.29±2.0-12.3±14 (aquatic foods), 4.86±1.7-5.89±0.8 (dairy products), 4.53±0.8-6.32±1.1 (edible oils), 3.32±1.3 (eggs), 3.54±1.0-4.80±1.5 (fruits), 4.16±2.7-4.40±0.8 (vegetables), and 6.12±2.0-6.62±0.9 (cereals). The estimated average daily intake of OCPs was 5.91, 12.5, 4.41, 6.40, 1.53, 5.14, 3.95, and 16.7 ng/kg bw/day through the consumption of meat products, aquatic foods, dairy products, edible oils, chicken eggs, fruits, vegetables, and cereals, respectively. The health risk of residual OCPs via ingestion of foods considered in this study was <1, which implied no potential health risk at the current consumption rate. However, regular monitoring of OCPs residues in food is highly recommended. Finally, the method scaled the analytical Eco-Scale evaluation and Green Analytical Chemical Procedure Index as "an acceptable green analysis method."

Human health risk assessment of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) pesticide residues in fruits and vegetables in Nigeria

The residues of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in forty-eight (48) composite fruit and vegetable samples (carrot, cucumber, tomato, and watermelon) were qualitatively and quantitatively determined using gas chromatography equipped with electron capture detector (GC-ECD). Safety indices such as the estimated average daily intake (EADI), cancer benchmark concentration (CBC), hazard quotient (HQ) and index (HI), and hazard ratio (HR) were also estimated. Results showed the predominance of HCH and its isomers in the fruits and vegetables as compared with the DDTs. The most predominant HCHs in all the fruits was α-HCH with mean concentrations of 2.704 ± 2.488 mg kg-1 (carrot), 1.536 ± 1.036 mg kg-1 (cucumber), 6.814 ± 2.967 mg kg-1 (tomato), and 9.241 ± 2.735 mg kg-1 (watermelon). The analysis showed that the levels of pesticide residues detected in 25 to 100% of the fruit and vegetable samples were above the UK/European Commission Maximum Residue Limits (MRLs). The non-carcinogenic health risk estimates showed that only α-HCH in tomatoes and watermelon had HQ > 1 which indicates the possibility of systemic health risk in children consumers. The carcinogenic health risk showed that only α-HCH and γ-HCH in children and α-HCH in adults had HR > 1 for tomato and watermelon which implies the possibility of carcinogenic health risk from its consumption. It is therefore paramount to institute a policy and regulatory framework for regular monitoring of pesticide residues in fruits and vegetables in Nigeria in order to ensure food safety for consumers and protect human health.

Bioaccumulation of Organochlorine Pesticides, Procamallanus sp. (Baylis, 1923) infections, and Microbial Colonization in African Snakehead fish Sampled from Lekki Lagoon, Lagos, Nigeria

The exponential rise in the Nigerian population has necessitated the use of agrochemicals for enhanced agricultural yields to meet the ever-rising demand for food. However, agrochemicals such as organochlorine pesticides (OCPs) have caused several devastating health and ecological challenges. The study was therefore aimed at assessing the bioaccumulation of OCPs and the associated parasitological and microbial susceptibility in P. obscura to determine the possible ecological impacts of the chemical. A total of 106 specimens of Parachanna obscura fish species were sampled between July and November 2019 from Lekki Lagoon in Lagos, Nigeria. Four culture media, namely nutrient agar (NA), MacConkay agar (MCA), eosin methylene blue (EMB), and sabouraud dextrose agar (SDA) were employed in microbial culture. These microbes were subjected to ceftazidime, ceftriaxone, cefuroxime, gentamicin, ofloxacin, augmentin, nitrofurantoin, ciprofloxacin, and erythromycin to test for resistance, susceptibility and intermediate statuses before and after curing. OCPs were tested in the water, sediment, and tissues of P. obscura using gas chromatography flame ionization detector (GC-FID). P. obscura sampled in the lagoon had poor growth exponent which was characterized by negative allometry (slenderness) in the sampled fish. Although the incidence of parasitic infection in the fish was not alarming, the situation might be aggravated if the prevalent anthropogenic activities persist, resulting in immunosuppression. Regulation of anthropogenic activities in the catchment area is recommended to forestall the prognosis of health and environmental hazards associated with the agricultural, industrial, pharmaceutical, and municipal activities around the lagoon. Bacteria that conferred the most resistance to the majority of the antibiotics were Staphylococcus sp., Micrococcus sp. Escherichia coli and Klebsiella sp., testing positive to plasmid profile. They conferred high resistance to the antibiotics before plasmid curing but became highly susceptible post- plasmid curing. This implies that the gene for resistance in the bacteria isolates was plasmid-mediated, that is, they were obtained from the environment. In the event of an outbreak of waterborne diseases such as cholera, typhoid, dysentery, and diarrhea, there may be non-response to treatment among the infected inhabitants. The incidence of antibiotic resistance in bacteria colonies recorded in this study is of great public health concern, given the possibility of the antibiotic-resistant bacteria strains being passed to humans through fish consumption, resulting in increased multi-drug resistance in humans. Regulation of anthropogenic activities around the lagoon is recommended to forestall prognosis of health and environmental hazards associated with OCPs from agricultural, industrial, pharmaceutical, and municipal sources.

Organopesticides and fertility: where does the link lead to?

Organopesticides (OPs) are a group of various synthetic chemicals prevalently used in agriculture and homestead plantations. OPs were originally developed to remove insects, weeds, and other pests from agricultural fields for improving crop yields. Modern pesticides including organochlorine pesticides, organophosphorus pesticides, and amido-formyl ester are closely related to our lives. Many people are exposed to various OPs during farming practice. OPs can cause adverse effects and provoke serious impacts on normal reproductive functions of humans, resulting in loss of fertility. The effects of OPs in the reproductive system include association with fluctuation in the levels of sex hormones, delayed menstrual cycle, ovarian dysfunction, alteration in ovary weight, changes of follicle growth, altered oocyte feasibility, and changed the quality of spermatogenesis. Current literature clearly states that exposure to various OPs can impair the fertility of women and cause a high risk of reproductive potential. However, investigations on OPs exposure to woman fertility remain scarce. This review highlights effects of exposure to OPs on the fertility of occupational women and mechanisms of action involved in such effects on the reproductive function of women along with their related impacts.

Human Health Risk Evaluation of Organophosphate Insecticide Residues in Post-Harvest Cowpea in Gwagwalada, Abuja, Nigeria

BACKGROUND

Cowpea is a leguminous crop commonly grown and eaten in Nigeria. Organophosphate insecticides are frequently used to control insect populations in cowpea crops.

OBJECTIVES

The present study was conducted to investigate the concentrations of organophosphate insecticide residues in cowpea varieties in Gwagwalada, Nigeria, and assess health risks to consumers.

METHODS

Samples of brown and white cowpea varieties were collected from Gwagwalada market, Abuja, Nigeria. Concentrations of organophosphate insecticide residues in the cowpea samples were analyzed by gas chromatography-mass spectrometry with selective ion monitoring. Risk evaluation was carried out by the determination of estimated daily intake, hazard quotient and chronic hazard index.

RESULTS

The organophosphates detected in the cowpea varieties were malathion, parathion, ethion and carbophenothion. The concentrations of insecticides in the cowpea types were higher than the maximum residue limits recommended by the European Union (EU) and the Agency for Toxic Substances and Disease Registry (ATSDR). The hazard quotient values were less than 100% for malathion, parathion and ethion in the cowpea varieties for adults and children. The hazard quotient of carbophenothion for adults was below 100% for the cowpea types, while the hazard quotient surpassed 100% for children. The chronic hazard indexes for children were 364% and 276% for the brown and white cowpea types, respectively.

CONCLUSIONS

The results obtained in the present study indicate that consumers, particularly children, may be exposed to health risks through the consumption of cowpea types. Consequently, monitoring and regulation of organophosphate insecticide usage in Nigeria should be intensified.

Occurrence and Human Health Risk of Dichlorodiphenyltrichloroethane (DDT) and Hexachlorocyclohexane (HCH) Pesticide Residues in Commonly Consumed Vegetables in Southwestern Nigeria

BACKGROUND

Fluted pumpkin (Telfairia occidentalis) and amaranth (Amaranthus spp.) are common leafy vegetables produced and consumed in southwestern Nigeria. These vegetables attract insect pests which are controlled by pesticides that may have adverse impacts on human health.

OBJECTIVES

To determine the levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) pesticide residues in the two vegetables and evaluate the potential health risks associated with their consumption.

METHODS

The pesticide residue levels were quantitatively and qualitatively determined using a gas chromatograph coupled with electron capture detector. Health risk assessment were performed using estimated average daily intake and hazard indices for two weight categories: children (16.7 kg) and adults (60 kg).

RESULTS

The results showed that delta-HCH, DDT and methoxychlor were predominantly detected in the two vegetables from both farms and markets. In amaranth, the mean concentration of methoxychlor, DDT and delta-HCH were 4.590 ± 2.774 mg/kg (dry weight (dw)), 0.757 ± 0.457 mg/kg (dw) and 0.577 ± 0.390 mg/kg (dw), respectively, while fluted pumpkin levels were 6.223 ± 2.489 mg/kg dw (methoxychlor), 0.504 ± 0.056 mg/kg dw (delta-HCH) and 0.486 ± 0.123 mg/kg dw (DDT). The levels of HCH and DDT residues were generally above the United Kingdom/European Commission maximum residue limit. The analysis of health risk estimates for non-carcinogenic risk revealed that for both vegetables, the hazard quotient for p, p' DDT and methoxychlor was >1 for both children and adults. The health risk estimates for carcinogenic risk revealed that hazard indices values were >1 for children for both vegetables and alpha-HCH had a hazard index >1 for adults for amaranth. This means the residue exceeds acceptable standard and present potential risk to consumers of these vegetables.

CONCLUSIONS

The results obtained from the present study indicate that consumption of amaranth contaminated with alpha-HCH could pose a carcinogenic risk for adult consumers. The consumption of the two vegetables could pose both non-carcinogenic and carcinogenic health risks to children and adults. Therefore, there is need for strict enforcement of regulations on pesticide usage to minimize human health risks.

COMPETING INTERESTS

The authors declare no competing financial interests.

Dietary exposure assessment of organochlorine pesticides in two commonly grown leafy vegetables in South-western Nigeria

Organochlorine pesticides (OCPs) are persistent pesticides whose usage have been banned or restricted worldwide and the presence of its residues in vegetables could affect its nutritional quality as well cause adverse health effects. This study quantified the OCP residue levels in commonly grown and consumed vegetables and assessed the carcinogenic and non-carcinogenic health risks from the consumption of the contaminated vegetables. The OCP residues levels in the extract from the vegetables were determined using a Gas Chromatograph coupled with Electron Capture Detector (GC-ECD). Health risk estimates were analysed using Estimated Average Daily Intake (EADI), Hazard Index (HI), and Hazard Ratio (HR) for children (16.7 kg) and adults (60 kg) weight categories. The residue analysis indicated that amaranths had the highest mean concentration of endrin aldehyde (2.987 ± 0.391 mg kg^-1) and endosulfan sulfate (0.661 ± 0.280 mg kg^-1), while in fluted pumpkin, the highest mean concentrations were endrin aldehyde (3.491 ± 0.376 mg kg^-1) and endosulfan sulfate (2.775 ± 0.644 mg kg^-1). The percentage of the detected OCP residues above Maximum Residue Limits (MRLs) ranged from 25% to 100% for both vegetables. Non-carcinogenic health risk estimates for the children weight category showed that aldrin, dieldrin, endrin, endrin aldehyde, and heptachlor detected in both vegetables had HI > 1. While for adults, only aldrin, dieldrin, endrin, and endrin aldehyde revealed non-carcinogenic effect in both vegetables. Human risk estimations for the carcinogenic health effect for the two vegetables showed that aldrin and dieldrin could pose carcinogenic health risks to adult, while aldrin, dieldrin, heptachlor and heptachlor epoxide could pose carcinogenic health risks to children. The results revealed both non-carcinogenic and carcinogenic health risks for the consumers of the contaminated vegetables from the selected locations in South-western Nigeria.