ORGANOCHLORINE PESTICIDES RESIDUE IN COCOA BEANS (THEOBROMA CACAO) AND SOILS OF COCOA PLANTATIONSIN ONDO STATE NIGERIA

ABSTRACT

The study investigated the levels of organochlorine pesticide residues in both cocoa beans and soils of cocoa plantations in selected farms in Ondo State. Soil samples and cocoa pods were collected  from four major farms in the State. The pesticide residues  were extracted, cleaned up and analysed using Gas Chromatography-Electron  Capture Detector (GC-ECD). In the analysed cocoa samples, the ranges of the mean concentrations of the organochlorine pesticides were: α-HCH (ND-0.094 mg/kg), β-HCH (ND-0.371 mg/kg), γ-HCH (ND-0.032 mg/kg),  δ-HCH  (ND-0.032  mg/kg),   heptachlor  (ND-0.272   mg/kg),  heptachlor-epoxide (0.040-0.185 mg/kg), aldrin (ND-0.117 mg/kg), dieldrin (0.052-1.110 mg/kg), endrin (0.297-

1.516  mg/kg),  endosulfan  I  (1.719-10.689  mg/kg),  endosulfan  II  (0.028-0.570  mg/kg), endosulfan sulphate (ND-3.865 mg/kg), p,p’ DDT (ND-0.100 mg/kg), cis-permethrin (0.078-

0.662 mg/kg), trans-permethrin (0.085-0.927 mg/kg). However, the levels of aldrin, dieldrin, endrin and endosulfan  in the cocoa samples analysed  were found  to be high  and above Maximum Residual Limits (MRLs) established  by WHO/FAO  (HCH  isomers, heptachlor, heptachlor-epoxide,  aldrin,  endrin  and  dieldrin  (0.020  mg/kg)  and  endosulfan  I,  II  and sulphate  (0.100  mg/kg))  and  European  Union  (α-HCH,   β-HCH  and  δ-HCH  isomers, heptachlor,  heptachlor-epoxide,  and  dieldrin  (0.020  mg/kg),  γ-HCH (1.000  mg/kg),  p,p’- DDT, aldrin (0.050 mg/kg) and endosulfan I, II, cis- and trans-permethrin (0.100 mg/kg)) . In the  soil  samples  analysed,  the  ranges  of  the  mean  concentrations  of  the  organochlorine pesticides were: α-HCH (ND-0.064 mg/kg), heptachlor-epoxide (0.059-1.384 mg/kg), aldrin (ND-0.450 mg/kg), dieldrin (0.041-0.066 mg/kg), endrin (0.136-0.567 mg/kg), endosulfan I (0.319-1.451 mg/kg),  endosulfan II (0.033-0.113 mg/kg), endosulfan sulphate (0.764-1.711 mg/kg),  cis-permethrin  (0.077-0.259  mg/kg),  trans-permethrin  (0.079-0.151  mg/kg)  The mean  concentration  of  aldrin,  dieldrin,  endrin,  endosulfan  (I  and  II)  in  the  soil  sample analysed    were    above    the    MRLs    of    the    analytes    established    by    Netherlands aldrin(0.0025mg/kg),dieldrin(0.0005mg/kg),endrin(0.001mg/kg),endosulfanI(0.050mg/kg),en

dosulfanII(0.050mg/kg).  p, p’ DDT was below detection limit (10-4  mg/kg) in 50% of  the

analysed cocoa and all the soil samples. Similarly, HCH isomers and p,p’ DDT were below detection limit (10-4  mg/kg) in the soil samples analysed except Oluji-1 where α-HCH was detected. The results of the bioaccumulation factors showed that endosulfan, dieldrin, endrin heptachlor, heptachlor-epoxide,  cis- and trans-permethrin were bioaccumulated in the cocoa samples from the selected farms. The high bioaccumulation factors of endosulfan I (7.367 in

Oluji-1, 3.084 in Oluji-2 and 14.525 in idanre), Dieldrin (27.073 in Oluji-2, 7.477 in Owena), and  cis-  and  trans-permethrin  (1.8  and  11.734  in  Owena,  8.597  and  8.429  in  Idanre respectively)  give cause for concern considering  the adverse  health  hazards pose by high accumulation of these pesticides on man. This indicated recent use of these pesticides despite the ban imposed on their use. The results of ANOVA showed that there was no significant difference between the mean concentrations of the pesticide residues in all the cocoa samples (p<0.05). Similarly, no significant difference was observed between the mean concentrations of the analytes in all the soil (p<0.05).

CHAPTER ONE

1.0       INTRODUCTION

Cocoa is an important tropical tree crop which does not only provide farmers with much desired income to meet their basic family needs1  but also serves as aforeign exchange earner for many West African countries like Nigeria, Ghana, Côte d’Ivoire, Cameroon and Togo.Its botanical name, Theobroma  Cacao, given by Swedish natural  scientist Carl Von Linne denotes its rich taste and high nutritional value which make it irresistible to both young and adult especially when processed into diverse products such as chocolate, sweet, cocoa drink, cocoa biscuit, cocoa bread, cocoa cake, cocoa flakes, cocoa popcorn, cocoa jam, cocoa

jelly, cocoa cream, cocoa wine and spirit, etc.2-4

Cocoa was believed to have originated in the hot, humid region near the source of the River Amazon in South Africa and introduced into Nigeria in 1874.1,5In Nigeria,  Cocoa is grown mostly in Southern States such as Ondo, Oyo, Ogun and Osun. It is a tropical lowland

crop  which  flourishes  best  where  the  annual  rainfall  is  at  least  1140mm  with  mean temperature below 170C. It requires shade to reduce moisture evaporation especially at the nursery and the early stages of its establishment in the field. It also requires a deep, fertile and

well aerated  loamy  soil which  must  beloose  and  friable.  The  cocoa  plant  when  mature reaches a height of 7.5 to 10.5m.6

Before 1960, exportation of cocoa accounted mainly for the agricultural export, which made over 80% of the Gross National Product (GNP) of the Nigerian economy.7This showed that cocoa was the chief source of foreign exchange earnings for Nigeria before the discovery

and exploration of crude oil. Despite the oil boom experienced in Nigeria, cocoa still serves as the major agricultural export crop and accounted for about 38% of agricultural export in

1997.8Being an important agricultural produce, cocoa provides employment for the farmers

in  the  remote  villages  and  millions  of  individuals  all  over  the  world  involved  in  its processing, marketing and distribution. It is imperative to note that large scale production of cocoa can solve the problems of unemployment in Nigeria. This is because the world demand for cocoa  and its derived  products  is ever increasing  and remains  insatiable.  Eighty-five percent (85%) of the cocoa demand of the European Nations is  from West Africa where

Nigeria is one of the major exporters5. This showed that the final destination of West African

cocoa is Europe.

Although, the cocoa producing Nations in West Africa derive revenue from the export of cocoa to Europe, much more revenue could be derived if the exported  cocoa is being processed  within  the  West  African  region  and  the  finished  products  is  exported  for  the consumption of the European nations after the satisfaction of the local demands. This could only be achieved if laws are enacted and necessary provisions are made to provide a very conducive environment for the farmers and the local processing industries to strive.However, the discovery of abundant natural resources,  such as  crude  oil in Nigeria, gold in Ghana, probably led to the reduction in effort of most African Governments to make available these required provisions. Consequently, cocoa farming is now left mostly to smallholder farmers

(with farm size less than 5 hectares) who rely on the crop as the primary source of income.8

Many of these farmers are geographically isolated, illiterate, poorly informed and have very limited resources for proper crop management. This development has caused a sharp decline in cocoa production as many of the farmers still adopt the traditional methods of farming which is very inefficient and pose high risk to the farmers8.

Unfortunately,  the enormous effort of these farmers at sustaining production under high risk conditions was not most often reflected in their output as pests and diseases largely contributed to decline in cocoa production.9In Nigeria, decline in cocoa production started in

1971 and 1972 with yield of 255,000 and 241,000 metric tonnes respectively5. The lowest

yield in the 70’s was recorded in 1978 with output of 137,000 metric tonnes5. Yields declined further from a peak of about 350,000 metric tonnes in the mid 80’s to about 58,700 metric tonnes in 19865. According to THISDAYLIVE Newspaper report issued on 21st January, 2014, the cocoa production in Nigeria was 250, 000 metric tonnes in 2011, 300, 000 metric tonnes

in 2012, and 350, 000 metric tonnes in 2013. This showed an annual increase in production by 50, 000 metric tonnes but when compared to the annual cocoa production from other West African countries in the same period (Ghana cocoa production was  between 850, 000 – 1,

000, 000 metric tonne per annual and Cote d’Ivoire cocoa production was in the range 1.2 –

1.4 million metric tonnes per annual), it would be obvious that the growth rate was not only insignificant but also the annual output was too small for the most populated black Nation (Nigeria) that is expected to champion the course of self sustenance in food production in Africa.

Major contributors to this decline were pests as 25-30% loss in yield of cocoa was attributed to the cocoa mired, Sahlbergella singularis while about 17% was lost through the feeding of the cocoa pod borer Characoma strictigrapta10, 11. The collective efforts of minor pests (such

as the shield bug, Bathycoelia thalassina, the pod miner, Mamara species, the root-feeding

termites,    Macrotermes    bellicosus,Mesohomotoma     tessmanniand    the    cacao    thrips, Selenothrips  rubrocinctus)could  become significant  especially under suitable  conditions  in young cocoa or ageing cocoa plantations.

It is important  to note that  several concerted  research efforts  have been made  to develop various control techniques (such as cultural, biological and chemical) which could be adopted for integrated management of the major and minor pests of cocoa in Nigeria. It is however quite unfortunate to note that many of the findings of such research hardly reached the local farmers and when they did eventually, the inability of the farmers to read and write often hindered the proper interpretation of those findings.  Despite the various mechanisms

developed for pest management, the farmers rely greatly on the use of pesticides (chemical control  technique)  because  it  provides  immediate  and  quicker  remedy  in  the  periods  of serious pest outbreaks.11

There  are  over  seven  hundred  (700)  chemicals  in  use  as  pesticides,  which  are

formulated  into  about  thirty-five  thousand  products  classified  as insecticides,  herbicides, fungicides  and rodenticides.12Although,  pesticides  are known to be very  efficient  in pest control,  reliance  and prolonged  application  of thesesynthetic  chemicals  had given rise to numerous problems which affected the food chain and posed negative impact on biological diversity.  It  has  been  established  that  pesticides  application  could  lead  to  serious  health hazard ( such as epilepsy, stroke, respiratory disorders, leukemia, convulsion, brain and liver tumors ) and environmental  pollution  as  it is often manifested  in the disturbance  of the ecosystem,which include destruction of some natural vegetation, pollution of the important water bodies (ground water, river water, drinking water), soil and air as well as reduction and extinction of some aquatic species and wildlife population.13-15

In Nigeria, cocoa farmers use different  insecticide  formulations  including the  very notorious organochlorine types. Due to their bioaccumulation throughout the food chain and prolonged persistence in the environment coupled with numerous associated health risk, food and environmental  regulatory bodies in many developed  and  developing nations,including National Agency for Food and  Drug Administration  and  Control  (NAFDAC)  in Nigeria, place ban on the use of most pesticides especially those with organochlorine formulations in line with the new European Union Legislation on pesticide use.16  Despite, the ban on these chemicals, the hazards associated with them  still remain for long period as many of them possess extended half-life especially the organochlorines which are very stable and persist for a long period of time.The problem  is further complicated  as these compounds have many

derivatives which are very soluble in body fat and can move with relative ease through the food chains.

It  is  therefore  very  expedient  to  provide  adequate  quantitative  and   qualitative information on these banned pesticidesand their derivatives in soil, farm produce (e.g. cocoa) and  water.  This  is to  assist;  the  farmers  (who  use these  pesticides),  government  (in the formulation of policy)and the general public (to make the consuming populace aware of the associated   danger  inherent  in  consumption  of   farm  produce  and  water  contaminated withpesticides).  These can only be achieved  through concerted research effort tailored and targeted towards acquiring this much important information.

1. 1     STATEMENT OF PROBLEM

Use of Pesticide in Nigeria has been on the increase since its introduction in early 50s for  cocoa  production.  To  attain  acceptable  levels  of  crop  production,  Nigerian  cocoa production is strongly dependent on pesticides. The campaign against mired attack on cocoa, which followed the recommendation of Lindane in 1957, lead to highly significant increase in cocoa production from an average of 103,000 tons per annum in 1961- 67 periods to 212,000 tons per annum in 1961-65 periods.16  This shows to a  large extent that the use of some pesticides is of significant importance to the production of cocoa. Since cocoa is one of the major  cash crops that contribute  towards the  Gross Domestic  Product  (GDP)  of Nigeria through foreign exchange, increasing the productivity of cocoa is tantamount to an indication of  economic  development.  However,  most  recently,  the  developed  nations  discovered

increase in the case of cancer among their citizens. This prompted the European Union to be conscious of the quality of food products meant to be consumed among her  citizens.  This development  is in connection  to pesticide  residue  observed  to be high  in most imported agricultural produces and products. Thus, within the European Union (EU), as in many parts of the world, legislation regulates the supply and use of  pesticides.  It has two important

components: Directive 91/414, which defines active substances permitted for use in the EU; and Regulation 396/2005, which defines the maximum levels of residues (MRLs) permitted in food and feedstuffs in the EU. Regulation 396/2005 came into force on 1st  September,

2008 and has significant implications.17  From 1st September 2008, any foodstuffs, including

cocoa  as  an  imported  commodity,  containing  pesticide  residues  above  the   temporary maximum levels of residues (tMRLs) is considered illegal in the EU. In the new legislative framework, tMRLs have been set on beans but also apply to cocoa and chocolate products. In the light of this development, it is imperative for cocoa exporting countries like Nigeria to make concerted effort to ensure their cocoa produce meet up with the set standards as Europe is the final destination of cocoa produce in most developing nations.

Since cocoa produce that has its pesticide residue far above the minimum required level stated by EU are restrained in the foreign exchange market, this implies that those local farmers that are not aware of this legislation are only producing for  themselves. Knowing well that the market of cocoa is not only situated within the country but extends outside this country, hence farmers that are still using the banned chemicals will definitely be running at a loss. Information available at theFederal  Environment  Protection Agencyindicated  that the Federal Government of Nigeriarecognizes the problems of pesticides use andhas put in place legal and administrativeprocedures aimed at regulating and monitoringpesticide manufacture, importation,  distribution,use  and  disposal  so  as  to  protect  users  as  well  as  the  nation’s

environment from the effects of thesepesticides.16   However, the marketing of pesticides  in

Nigeria  is very much unorganized  and lacks proper  legislative  control.  This has  made  it difficult to determine the various market sizes, types, and shares of pesticides in use. Hence there is no dependable official statistics on the type and amount of pesticides imported into the country.18This is indeed a pathetic situation that requires immediate attention, which can only come from well structured and organized research.

1. 2     OBJECTIVE OF THE STUDY

The   intensive   use   of   pesticides   leads   to   environmental   problems   such   as contamination of soil, farm produce and underground water. On application of pesticides to destroy pests and pathogens, only 15% of the applied amount hits the targeted pests, with the remaining 85% being distributed in the soil and air.19 The soil is the main matrix for pesticide disposition and the bulk of pesticide residues are generally confined to the upper 20cm of the top soil.20  Pesticide residue in the soil can move  from  the surface when they dissolve  in runoff water,  or percolate  down through  the  soil, and eventually reach the  groundwater. Plants take up pesticides dissolved in water. These pesticides are distributed in most part of the plants especially in fruits rich in fat like cocoa beans.   Most farmers are only interested in

protecting their crops from pests in order to get good harvest but have little concern for the detrimental effects of these pesticides on the soil, environment and their health.20  In order to comply with the maximum residue limit regulation and produce high quality cocoa beans for exportation,  it  becomes  expedient  to  assess  organochlorine  –  α-HCH,  β-HCH,  γ-HCH, Heptachlor,   Heptachlor-epoxide   (B),  Aldrin,   Dieldrin,   Endrin,   Endosulfan   (I,  II  and sulphate),    DDT,  cis- and trans-Permethrinresidue  in  cocoa beans and soil from selected cocoa plantations in Ondo State, Nigeria.

The general objective of the study is to determine organochlorine pesticides residue in both cocoa beans and soil of cocoa farm, and assess the pesticide management practices among farmers in selected cocoa plantation in Ondo state, Nigeria. The specific objectives are to:

(i) Identify pesticide management practices adopted by the farmers in the study area

(ii) Determine the level of organochlorine  pesticides residue in the cocoa beans from  the selected farms

(iii) Determine soil physicochemical parameters (soil organic matter / total organic carbon, particle size analysis and pH)andthe level of organochlorine pesticides residue in the top soil of the selected cocoa farms

(iv) Evaluate the bioaccumulation factor

(v) Compare the values of the organochlorine pesticides in cocoa and soil with the accepted

Maximum Residual Limits (MRLs) established by international organisations

(vi) Provide required suggestions and make useful recommendations based on the findings of this research to both the farmers and the Government.

1. 3     JUSTIFICATION OF THE STUDY

Until recently,  environmental  pollution  monitoring  and  control  have  not  received much attention in most part of cocoa producing States in Nigeria. One important aspect of this is the availability of adequate and reliable data on the levels of key pollutants resulting from   applications   of   pesticides.   The   occurrence,   persistence,   and   consequences   of organochlorine  pesticides  in the environment  will  continue  to represent  an environmental issue  for  contemporary  and  future  generations.  To  address  this  issue,  it is  necessary  to determine the levels of organochlorine pesticides in some areas of likely predominance. This informs the choice of the selected study area, Ondo State. This is a major cocoa producing area in Nigeria where large cocoa plantations are situated. Thus, the findings of this research can serve as a basis on measure of the presence and persistence of organochlorine pesticides in major cocoa farms in Nigeria.

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