Risk Assessment of Commonly Used Major Pesticides for Tomato (Solanum lycopersicum L.) Cultivation in Bangladesh
Abdullah- Al- Numan¹, Md.Mahmudul Hasan Khan^2*, Razi Uddin², Md. Mahbubur Rahman³, Mohammad Sarfuddin Bhuiyan⁴, Nadia Akter^5
1Department of Agricultural Chemistry, Sher-e-bangla Agricultural University, Bangladesh
^*2Scientific Officer, RARS, Bangladesh Agricultural Research Institute, Barisal, Bangladesh
³Scientific Officer, RARS, Bangladesh Agricultural Research Institute, Hathazari, Bangladesh
⁴Senior Scientific Officers, OFRD, Bangladesh Agricultural Research Institute, Bandarban, Bangladesh
⁵Scientific Officer, Bangladesh Rice Research Institute, Gazipur, Bangladesh
Received Date: 27 August, 2018; Accepted Date: 03 September, 2018; Published Date: 12 September, 2018
^*Corresponding author: Md.Mahmudul Hasan Khan, Scientific Officer, RARS, Bangladesh Agricultural Research Institute, Barisal, Bangladesh. Tel: +880017126693101; Email: mhasan.bari12@gmail.com
Citation: Numan AA, Khan MMH, Uddin R, Rahman MM, Bhuiyan MS, Akter N (2018) Risk Assessment of Commonly Used Major Pesticides for Tomato (Solanum lycopersicum L.) Cultivation in Bangladesh. Adv in Nutr Fd Sci: ANAFS-109.

Abstract

     The aim of the present study was risk assessment that is hazard characterization and human exposure assessment of chemically treated tomato available in different production areas of Bangladesh. To do the risk assessment primarily a list of available pesticides in three different region of Bangladesh (Mymensingh, Narshindgdi and Jessore) was prepared by field visit and survey. Secondarily to determine the potential health risks associated with the exposures to these pesticides a scenario based on MSDS (material safety data sheet) evaluation was given. Moreover, ADI (acceptable daily intake), MRL (maximum residue level) and RfD (reference dose) value of agro-chemicals were also used which were referred by different organizations like WHO, EPA, FDA, EFSA, FAO, Codex. According to the field survey, most common agro-chemicals were taken to the study. All the pesticides available in the markets were found as authorized pesticides and none of them were found to be extremely hazardous according to the WHO recommended classification except Carbofuran. The present study indicates that there is a high chance to have residual effects of pesticides in tomato as a result of pre-harvest or postharvest application. Most of the farmers do not know about health risk issue of using agro-chemicals. It is important to aware the farmers to follow the recommended dose of registered pesticides and the consumers to proper handling and processing of tomato for safe consumption. Information on health risk, exposure assessment was also highlighted for public awareness. Suggestions were provided on the handling and processing such as washing, cooking, boiling, packing, storage etc. for the safety of the consumers. Farmers use both recommended and non-recommended pesticides for tomato production. In most cases farmers do not follow the recommended dose and rational pesticide application. Among the most commonly used pesticides, Carbofuran was found to be highly hazardous.

Keywords: ADI; Assessment; Pesticide residue, MRL; survey; MSDS; RfD; WHO

 Introduction
      Tomato (Solanum lycopersicum L.), which is botanically a fruit and not a vegetable, is loaded with all kinds of health benefits for the body. One of the most well known tomato- eating benefit is its lycopene content. Tomatoes are equally as nutritious as they are in other variable forms. It plays a vital role in providing a substantial quantity of vitamin C and vitamin A in human diet [1]. Tomato is the most consumable vegetable occupying the top of the list as canned vegetable having multiple uses [2]. It is also suitable to grow in our agro-climatic condition. However, our average population has nutritional deficiency due to the traditional rice based food habit and lack of knowledge about balance diet. In addition food adulteration news via media is discouraging us to take fruit regularly. Proper science based risk assessment is essential to evaluate whether the agro-chemicals used for cultivation is actually threat for consumers during the time of consumption. Pesticide poisoning is a global health problem and it is more prevalent in countries like Bangladesh due to the non-judicial use. The incidence of pesticide poisoning is increasing according to the existing reports and it is estimated that about 5 million people die every year as a result of intentional, accidental and occupational exposure worldwide [3]. To combat insect pests and diseases of tomato and to achieve higher production, many pesticides are used that may leave certain amounts of residues on crops. Farmers tend to spray vegetables up to the time of harvest, and then transport directly to market with no waiting period. These create a very significant potential for pesticide residues causing negative health effects on consumers [4] Depending on the situation, pesticides could enter body by any one or all these routes.

       Typical sources of pesticide exposure include food on which we are giving stress. Because most of the foods we eat have been grown with the use of pesticides. Therefore, pesticides residues may be present inside or in the surface of these foods. In one hand we have food crisis, over population on the other hand we have problem on safety. So, risk assessment (i.e. hazard identification, hazard characterization, exposure assessment and risk characterization) for food safety is a burning national issue.  Survey reports conducted [5,6,7] at different locations of Bangladesh indicated that the farmers spray pesticide in their vegetable field irrationally, sometimes every day or in each alternate day. Due to the lack of knowledge and non-availability of sustainable alternatives to pesticide, farmers of Bangladesh become dependent on pesticide for crop production. Excessive and non-judicious use of pesticide has raised several environmental and social issues, as well as, destruction of agricultural ecosystem and development of resistance in insect pest, pathogens and weeds [8]. In Bangladesh, it is assumed that adulteration of pesticide is one of the major causes of such extensive use of pesticide. In the country report originated by FAO (2015) Corporate Document Repository, it is reported that the regulatory scheme for pesticide registration is systematic. But in practice, there are gaps between policies and implementation. While the intent of the ordinance and rules to monitor formulations and residue is commendable, the lack of facilities and trained analysts does not allow proper monitoring. Thus, specification of pesticides on the market may differ from those registered. So, concern on the purity in respect of active ingredient of the marketed brands of pesticides is therefore, likely key factor for repeated use of pesticides in vegetables. Due to absence or little amount of active material in the formulated pesticides, they do not work against insect pests and the farmers use more pesticide for better result [9]. Due to impurity of pesticide and low amount of active ingredient, farmers use more than recommended dose which are labeled and pest became resistant to that pesticide rapidly. According to this viewpoint, it has become significant to evaluate the brands of pesticide for quantification of their active ingredient (AI). So, the basic research objectives were:  To make a list of available agro-chemicals used during the cultivation of tomato, to characterize the hazardous effect of pesticides, to evaluate their exposure and predict the theoretical risk.

Materials and Methods
      For hazard identification a list of available agrochemicals generally used during the cultivation/harvest of tomato was prepared based on the field visit to three different areas of Bangladesh: Mymensingh , Norshingdi and Jessore. During field visit, Farmers’ interview was conducted following a formal set of questionnaire. Further information was also collected by visiting Upazila Agricultural Officer, Agriculture Extension Officer and different pesticide shops.  For hazard characterization and risk assessment the material safety data (MSDS) of registered and survey based agro-chemicals was compared and evaluated. Further evaluation was done via the material of the different authentic international organization’s website (such as FDA, EFSA, WHO). The degradation properties of those agro-chemicals which are influenced different post-harvest activity, packaging and transportation method was also considered [10,11].

Result and Discussion
Risk and Exposure Assessment of Major Pesticides
Sulphur:   In its native form, sulphur is an abundant, yellow crystalline solid. It can be found as the pure element and as sulphide and sulphate minerals. Sulphur is probably the oldest known pest management product in use. It Prevents powdery mildew, rose black spot, scab, rusts, and other diseases. It Can be used as a dust, wettable powder, paste or liquid. Controls red mites in tomato, citrus and other widespread crops when sulphur dioxide is at high concentrations. Other insects affected include white fly, thrips, some Homoptera, and gall midges. It does not subject to hazardous polymerization. Permissible exposure limit (PEL) has not been established by OSHA. Threshold limit value is 1ppm according to ACGIH. Sulphur is classified as class-III (slightly hazardous) according to WHO recommended hazard classification. In case of toxicity, large doses (15 grams) by mouth may lead to hydrogen sulfide production in the body, chiefly due to bacterial action within the colon. Rat-oral LD50= 175 mg/kg. Prolonged inhalation of dust over several years may cause respiratory disease, complicated by emphysema and bronchiectasis. Asthma and inflammation of the frontal and maxillary sinuses are frequent complications. Pulmonary function may be reduced showing increased, oxygen consumption, reduced respiratory volume, and impaired carbon dioxide diffusion capacity. Radiological examinations have revealed irregular opacities in the lungs and nodulation. ADI of sulphur is 200mg/kg body weight/day (EFSA), no MRL and RfD have been found. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

 Carbendazim: Carbendazim is one of the most widely used fungicides in tomato. It is a broad-spectrum benzimidazole fungicide and a metabolite of benomyl. It is stable in acids, forming water soluble salts. Half life in soil is 22-54 days. Ample evidence exists from experimentation that reduced human fertility is directly caused by exposure to the material. Ample evidence exists, from results in experimentation that developmental disorders are directly caused by human exposure to the material. Exposure to the material may result in a possible risk of irreversible effects. The material may produce mutagenic effects in man. Oral (rat) LD50: 6400 mg/kg Dermal (rat) LD50: 2000 mg/kg. ADI ranges from 0.01 to 0.08 mg/kg bw/day by (from table 6) and MRL value is 0.8 mg/kg (EFSA). RfD is 0.025 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

Iprodione: Iprodione is a dicarboximide contact fungicide with protective and curative action. It is a new member of neonicotinoid pesticides. It is Stable under normal conditions of use. PEL and TLV have not been established. Prolonged overexposure to iprodione can cause effects to liver, kidneys, and reproductive system. Iprodione produced benign testicular tumors in rats and benign liver and ovary tumors in mice when tested at a maximum tolerated dose. Overexposure to propylene glycol has been associated with kidney toxicity, liver toxicity (animals) and lactic acidosis. Oral: Rat LD50: 3,125 mg/kg (female) (estimated based on mortalities for doses tested) Dermal: Rat LD50: >5,000 mg/kg Inhalation: Rat 4-hr LC50: >2.09 mg/L.ADI ranges from 0.04-0.24 mg/kg-bw/day and MRL ranges from 01.5-6mg/kg. No RfD has been established. Oral LD50(rat) : >5000mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

Mancozeb:  Mancozeb is a dithiocarbamate non-systemic agricultural fungicide with multi-site, protective action on contact. It is a combination of two other dithiocarbamates: maneb and zineb. It is classified as class U according to WHO recommended hazard classification. PEL and TLV have not been established. Half life in soil is 0.1-18 days. A two-year feeding study of mancozeb in rats produced an increased incidence of thyroid tumors at 750ppm (29mg/kg/day). No evidence of carcinogenicity was observed in long-term studies with mice. ADI ranges from 0.02-0.06 mg\kg-bw/day and MRL value ranges from 0.2-5 mg/kg (from the table).RfD is 0.05 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

 Mancozeb + Metalaxyl: It is another widely used fungicide in tomato. This product is unlikely to react or decompose under normal storage conditions. Half life is 07-170 days. PEL and TLV have not been established. It is classified as class-III according to WHO recommended classification. Oral LD50 for rats >5000mg/kg. No toxicological effects were apparent in rats fed dietary doses of 5 mg/kg/day in a long-term study. Impaired thyroid function was observed as lower iodine uptake after 24 months in dogs fed doses of 2.5 and 25 mg/kg/day of Mancozeb, but not in those dogs fed 0.625 mg/kg/day. A major toxicological concern in situations of chronic exposure is the generation of ethylenethiourea (ETU) in the course of Mancozeb metabolism, and as a contaminant in Mancozeb production. ETU may also be produced when EBDCs are used on stored produce, or during cooking. In addition to having the potential to cause goiter, a condition in which the thyroid gland is enlarged, this metabolite has produced birth defects and cancer in experimental animals. ADI ranges from 0.02-0.08 mg/kg-bw/day (from the table) and no MRL value has been found. RfD is 0.06mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

 Malathion: Malathion belongs to the group of pesticides known as organophosphates, the same organophosphates weaponized in World War II for use as nerve agents. Malathion behaves similarly in pests, disrupting their nervous systems to the point of death. Although malathion controls numerous insect species, it’s commonly used to control aphids (Aphidoidea spp.) and spider mites (Tetranychus urticae) on tomato plants (Lycopersicon esculentum). It is stable and hazardous polymerization will not occur. Half life in soil is 01-25 days. PEL is 15mg/m³ and TLV is 1mg/m³ (ACGIH). It is classified as class-III according to WHO recommended classification. Oral (rat) LD50: 290 mg/kg, Dermal (rat) LD50: 4444 mg/kg. Not classifiable as to its carcinogenicity to humans. Evidence of carcinogenicity may be inadequate or limited in animal testing. ADI ranges from 0.03-0.08 mg/kg-bw/day and MRL ranges from 0.19-4 mg/kg (from the table).RfD is 0.02 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

 Chlorpyrifos: Chlorpyrifos (IUPAC name: O, O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) is a crystalline organophosphate insecticide, acaracide and miticide. Chlorpyrifos is moderately toxic to humans, and exposure has been linked to neurological effects, persistent developmental disorders and autoimmune disorders. Exposure during pregnancy retards the mental development of children, and most home use was banned in 2001 in the U.S. It is stable under recommended storage condition. Half life in soil is 11-141 days. PEL is 0.2mg/m³ (OSHA) and TLV is 0.2mg/m³ (ACGIH).It is classified as class II (Moderately hazardous) by WHO. Acute oral LD50 for rat：82 mg/kg .Acute dermal LD50 for rat: 203 mg/kg. Repeated or prolonged exposure to organophosphates may result in the same effects as acute exposure including the delayed symptoms. Other effects reported in workers repeatedly exposed include impaired memory and concentration, disorientation, severe depressions, irritability, confusion, headache, speech difficulties, delayed reaction times, nightmares, sleepwalking, and drowsiness or insomnia. An influenza-like condition with headache, nausea, weakness, loss of appetite, and malaise has also been reported. The EPA’s acceptable daily dose is 0.3 micrograms/kg/day. MRL value is 0.06(EFSA) and 0.5(CODEX) mg/kg. RfD is 0.005 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

Carbofuran: Carbofuran is one of the most toxic carbamate pesticides. It is marketed under the trade names Furadan, Carbofuran is highly toxic to vertebrates with an oral LD50 of 8–14 mg/kg in rats and 19 mg/kg in dogs. It is stable and hazardous polymeraization will not occur. Half life in soil is 3-60 days. PEL is 0.3mg/m³ (OSHA) and TLV is 0.1mg/m³ (ACGIH). IT is classified as Ib (highly hazardous) by WHO. Prolonged or repeated exposure increases the risk. Possible risk of irreversible effects may cause adverse effects on the bone marrow and blood-forming system. ADI is 0.00015mg/kg-bw/day (EFSA) and MRL value is 0.02-0.5 mg/kg.RfD is 0.005 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

 Carbosulfan: Carbosulfan is an organic compound adherent to the carbamate class. At normal conditions, It is not very stable; it decomposes slowly at room temperature. Its solubility in water is low but it is miscible with xylene, hexane, chloroform, dichloromethane, methanol and acetone. Half life in soil is 1-5 days. PEL and TLV have not been established. It is classified as class II (Moderately hazardous) by WHO. Acute oral toxicity: LD50 rat Dose: > 1,257.9 mg/kg. Acute dermal toxicity: LD50. No component of this product present at levels greater than or equal to 0.1% is identified as probable, possible or confirmed human carcinogen or potential carcinogen.(IARC, OSHA,NTP,ACGIH). ADI is 0.005 mg/kg-bw/day (EFSA) and MRL value is 0.05-0.1(from the table).RfD is 0.00007mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

Cartap: Cartap is a chemical compound from the group of thiocarbamates. It is considered stable for a period of 2 years in normal air, warehouse and light conditions, if kept in closed container. Half life in soil is 2-7 days. PEL and TLV have not been established. It is classified as class II (Moderately hazardous) by WHO. Acute oral LD50: Big female rat, 126mg/kg big male rat, 126mg/kg .Acute dermal LD50: Male, female rat : > 2000mg/kg. Animal studies did not detect any carcinogenic effects. No human information available. No ADI, MRL and RfD value is available for cartap. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull-China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc).

Diazinon: Diazinon is a synthetic chemical substance with a broad spectrum intertidal activity (Sarabia et al., 2009). Diazinon functions as an acetylcholinesterase (AChE) inhibitor. It is stable and hazardous polymeraization will not occur. Half life in soil is 21-103 days. PEL has not been established. TLV is 0.01 mg/m³ (ACGIH). It is classified as class II (Moderately hazardous) by WHO. Acute Oral LD50 (rat): 66 mg/kg. Not listed in OSHA, NTP, or IARC. Diazinon is classified by ACGIH as TLV-A4: Not Classifiable as a Human Carcinogen. No ADI value is available. MRL value is 0.5 mg/kg (Codex). RfD is 0.0025 mg/kg. (Source: MSDS of Hovensa of West Liberty University-USA, Sigma-Aldrich-Germany, HPM-India, Rayfull China, Nagarjuna Agrichem-India, Mingdou Agrichem-China, Chemical initiatives-South Africa etc) (Table 1- Table 11).

[/su_table]Table 7: Refeence Dose (RfD).

Conclusion
      The research was carried out to find out the risks associated with the major pesticides used for tomato cultivation in Bangladesh. The research included field survey in three different regions of Bangladesh namely Mymensingh, Narshingdi and Jessore. Results of field survey revealed that for tomato production farmers not only use pesticides that are registered for tomato but also use other pesticides that are not recommended for tomato. The most commonly used pesticides were sulphur, carbendazim, iprodione, mancozeb, mancozeb+metalaxyl, malathion, chlorpyrifos, cartap, carbofuran, carbosulfan and diazinon. In most cases farmers do not follow rational use of pesticides. Therefore, risk assessment of these pesticides was carried out by MSDS evaluation. Carbofuran was classified as highly hazardous (Ib) by WHO. Several mitigation processes was mentioned for the safe consumption of tomato. As most of the pesticides after application remain in the outer surfaces and can penetrate in lesser amount, washing, peeling or trimming can be effective ways of pesticide removal. Washing with dilute salt (sodium chloride) solution is a convenient method to lower the load of contaminants from food surfaces particularly fruits and vegetables. Chlorine water and dilute solutions of other chemicals can be used for disinfection of Tomato. The heat treatment can be given in many ways including pasteurization, boiling, cooking etc. depending upon the nature of food and aim of processing. Boiling is effective in reducing the level of water-soluble pesticides. A set of processing techniques such as drying and dehydration, canning of fruits and vegetables, juice/concentrate preparation etc. can reduce the amount of residue in the final product depending upon a set of parameters employed and length of processing. The packing process before shipment to retail outlets is generally effective in removing pesticides that may be present on peel at the time of harvest. Dispassion of pesticides in tomato results better in room temperature than cold condition while storage. Farmers should follow the recommended dose of registered pesticides. On the other hand consumers also need to be aware of proper handling and processing of tomato and its byproducts for safe consumption.

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