PJPHM-15-005-Takrama-cocoa

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Peak Journal of Public Health and Management Vol. 3(4), pp. 56-61, September, 2015http://www.peakjournals.org/sub-journals-PJPHM.htmlISSN 2329-2997©2015 Peak Journals

Full Length Research Paper

Cadmium contamination of cocoa beans and cocoa growingagricultural soils of Ghana: There is no cause for public alarm

Jemmy Takrama1*, Alex A. Afrifa1, Kwasi Ofori-Frimpong1, William A. Jonfia-Essien2, PaulAgyemang2 and Isaac Galyuon3

Accepted 10 September, 2015

Cadmium is a toxic environmental contaminant which occurs naturally and canaccumulate in agricultural crops and hence enter the human food chain.Cadmium has been detected in chocolate and other cocoa products. In

response to a call by the International Cocoa Organization (ICCO) (necessitatedby an EU proposal to set limit values in cocoa beans imports) to determinecadmium concentrations in agricultural soils and cocoa beans worldwide, theCocoa Research Institute of Ghana (CRIG) conducted a survey on cocoa soilsand beans in all the growing areas of Ghana to establish Cd levels. Cocoa beansamples (n=67) and agricultural soils (n=64) on which cocoa is grown togetherwith forest soils (n=64) adjacent to cocoa farms were collected from severalcocoa growing areas and analysed using Flame Atomic AbsorptionSpectroscopy. Results of this study showed that mean total Cd concentrationof the cocoa beans was 0.269 mg/kg in the range 0.248 - 0.336 mg/kg in nibs. Intop layer of soils, Cd occurred at an average of 0.047±0.002, 0.035±0.002 and0.035±0.002 mg/kg respectively in fertilized, unfertilized and forest soils.Analysis of our results with respect to international consumption dataconcluded that cocoa beans from Ghana do not pose any health risk withrespect to Cd accumulation on account of regular ingestion.

Key words: Cardio-vascular health, ICCO, malaria, natural cocoa powder, aquaregia, FAAS, TWI, EFSA, JECFA.

INTRODUCTION

Great interest is focused on cocoa and cocoa productsfor their beneficial health effects because of the highlevels of antioxidants they contain. Antioxidants of cocoa,highest in cocoa solids relative to wine and tea (Arts etal., 1999; Lee et al., 2003), have been proven to boost

cardio-vascular health (Cienfuegos-Jovellanos et al.,2009; Desch et al., 2010). The European Food Safety

Authority (EFSA) and the Food Advisory Committee ofthe United States of America have shown that flavonoidsin cocoa and chocolate products are associated with alower risk of cardiovascular disease and contribute to themaintenance of endothelium-dependent vasodilatation(EFSA, 2012). In Ghana, some physicians recommendcocoa products as a form of treatment. For instance,Physician Atsina (Winter, 2010) used cocoa powder asan adjunct to treatment of hypertension and diabetes in

his clinic in Ghana for several years. Addai (2010), astrong advocate for unsweetened natural cocoa powdeconsumption, recommended two to five cups a day tohelp protect against malaria. Cadmium, however, is atoxic element in humans and has become a topic of

concern in many countries. Exposure to cadmium maylead to renal tubular dysfunction (nephrotoxicity) and ahigh intake of Cd can lead to disturbance in calciummetabolism and formation of kidney stones. A high intakeof Cd can also affect the skeletal, endocrine, reproductiveand respiratory systems (WHO, 2010; EFSA, 2009Nawrot et al., 2006; Morgan and Sherlock, 1984). Foodaccounts for approximately 90% of Cd exposure to thenon-smoking population. Food groups that contributesignificantly to total cadmium dietary exposure are ricewheat, starch root vegetables, tubers, leafy vegetables,

1Cocoa Research Institute of Ghana(CRIG), P. O. Box 8, Tafo, Ghana.2Quality Control Company Ltd, P. OBox M45, Accra, Ghana.3Department of Molecular Biologyand Biotechnology, University o

Cape Coast, Cape Coast, Ghana.

*Corresponding author. E-mail

[email protected]


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Figure 1. Map of cocoa growing regions of Ghana showing sites (red dots) where sampling for cocoa beans andsoil samples were taken. Samples were taken from several farms around the towns indicated.

other vegetables and shellfish. Baby foods andchocolate/cocoa products are also important contributorsto the exposure of infants/toddlers andchildren/adolescents, respectively (EFSA, 2009; UNEP,2010).

To reduce consumers’ exposure to Cd in foods, the EChas proposed a Tolerable Weekly Intake (TWI) forcadmium of 2.5 µg/kg bodyweight (EFSA, 2009; EU,2014). The Joint FAO/WHO Expert Committee on Food

Additives (JECFA), however, has determined a TWI of 10µg/kg bodyweight for this contaminant as providingappropriate level of protection (JECFA, 2011). Currently,the Codex Alimentarius Commission (CAC) is in the

process of elaborating maximum limits of this metal inchocolate and cocoa-derived products to provideharmonized maximum limits to protect health and ensurefair practices in the cocoa trade (WHO, 2015). Theconsequences of Cd contamination in chocolates andcocoa-derived products are an issue of commercialinterest that impacts the economy of cocoa producingcountries (ICCO, 2012). In order to determine the actuallevels of cadmium concentrations in cocoa beans andagricultural soils in cocoa growing areas, the CocoaResearch Institute of Ghana (CRIG) in response to a callby the International Cocoa Organization (ICCO)

conducted this study to ascertain Cd levels prevalent inGhana as a precautionary measure. The results of theinvestigation are presented in this paper. The effect ofhigh consumption of natural cocoa powder is alsodiscussed.

MATERIALS AND METHODS

Study area

The cocoa growing areas as shown in Figure 1comprises all cocoa growing districts in Ghana. The

cocoa districts are similar to the geopolitical regions ofthe country except that the Western Region of Ghana isdivided into Western North (WN) and Western South(WS) cocoa districts because of its large size. The othersare Central Region (CR), Eastern Region (ER), AshantRegion (AR), Brong Ahafo Region (BA) and Volta Region(VR).

Sample collection and preparation

Approximately 0.5 kg each of fermented and dried cocoa


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beans were sampled from cocoa buying centres of theProduce Buying Company Ltd by Quality Control Officersof the Quality Control Company Ltd. For cocoa beans, 7-15 samples (0.5 kg each) were collected from the buyingcentres at the indicated locations in each of the sevencocoa regions.

Soils were sampled at three different depths: 0-15 cm,15-30 cm and 30-45 cm according to procedures adoptedby CAOBISCO/ECA (2011) and in each category thesoils were taken from fertilized cocoa farms, unfertilizedcocoa farms and forest soils adjacent to the cocoa farms.

At a given farm, three samples (about 2 g each) werecollected randomly from three different points in the farm.

A composite sample was prepared for each depth level.The soil samples were collected with the aid of earthchisel and hand trowel and placed in polyethylene bagsand sealed. In the laboratory, the samples weredisaggregated, air-dried, placed at room temperature for3 days after which they were ground. The samples weresieved using 2 mm sieves, packed into polyethylene bagsand stored until analysis.

Cocoa bean samples were prepared by separating theshells from nibs and Cd determined independently in thenib and shell fractions. Deshelled nibs (20 g) were groundin mortar and 1.0 g of this was digested in 40 ml aqua-regia (HCl/HNO3). An average of 3.0 g cocoa shells wasobtained from deshelling 20.0 g of cocoa beans. The 3.0g of shells were mixed and a sub-sample of 1.0 g wasdigested in 40 ml aqua-regia.

Cadmium in soils was determined by the Mehlichmethod (Mehlich, 1984): 2.0 g air-dried, ground andsieved soils were digested with 20 ml Mehlich-3 solution.The digest was filtered through Whatman No. 42 filter

paper into 25 ml volumetric flask. A Varian Spectra AA220FS model Flame Atomic Absorption Spectrometer(FAAS) (Varian Australia Pty Ltd, Mulgrave VIC 3170,

Australia) at the Cocoa Research Institute of Ghana wasused for the analyses. The concentration of Cd wasdetermined on the FAAS after calibration with referenceCd standard solutions. All chemicals used were ofreagent grade.

Data analysis

Means and standard deviations of soil and cocoa beans

data were determined using SPSS version 16 software.Difference between cocoa shells and nibs wasdetermined using the Student’s t-test. Graphicalrepresentations were made using Microsoft Excelprogram.

RESULTS AND DISCUSSION

Analysis of the cocoa beans data showed that, 60individual samples forming 90% of total bean samples

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collected contained Cd levels 0.6mg/kg but less than 0.8 mg/kg. However, the mean totaCd concentration of cocoa beans from the variousgrowing regions ranged from 0.248-0.336 mg/kg in thenibs (n=67) and 0.275-0.359 mg/kg in the shells (n=67

with a mean value of 0.269 mg/kg in nibs. There were nosignificant differences (p>0.05) in cadmium levels from althe cocoa regions (Figures 2 and 3). Further analysisusing t-test showed no significant differences between Cdlevels in shells and nibs (p>0.05) meaning similar levelsof Cd occur in both shells and nibs of cocoa beans.

Cd concentration was very low in all the soils in thecocoa growing regions of Ghana. In the top layer of soilsCd was found to occur at an average of 0.047±0.0020.035±0.002 and 0.035±0.002 mg/kg respectively infertilized, unfertilized and adjacent forest soils (Table 1)These soil Cd levels were not significantly different fromeach other (p>0.05). Cadmium concentrations at thedifferent depths of sampling (0-15, 15-30, 30-45 cm) werenot significantly different from each other (p>0.05)Between the cocoa regions; however, there weresignificant differences between Cd levels (p


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Figure 2. Cd concentration of cocoa beans from different cocoa growing districts of Ghana1.1WN=Western North cocoa district, WS=Western South cocoa district, CR=Central Region,

AR=Ashanti Region, BA=Brong Ahafo Region, ER=Eastern Region, VR=Volta Region, Cdconcentrations encountered in the beans were grouped into four categories: 0 to


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Table 1. Occurrence of Cd in cocoa growing soils at different depths1

Region

Depth 0-15 cm Depth 15-30 cm Depth 30-45 cm

Fert

Cd

mg/kg

Unfert

Cd

mg/kg

Forest

Cd

mg/kg

Fert

Cd

mg/kg

Unfert

Cd

mg/kg

Forest

Cd

mg/kg

Fert

Cd

mg/kg

Unfert

Cd

mg/kg

Forest

Cd

Mg/kg

WN 0.036 0.032 0.039 0.026 0.028 0.032 0.026 0.031 0.031WS 0.018 0.012 0.012 0.014 0.011 0.012 0.017 0.013 0.010CR 0.015 0.012 0.010 0.012 0.010 0.011 0.012 0.012 0.011 AR 0.038 0.036 0.030 0.034 0.032 0.035 0.032 0.032 0.040BA 0.055 0.049 0.065 0.040 0.038 0.070 0.043 0.036 0.065ER 0.082 0.053 0.041 0.047 0.046 0.033 0.036 0.034 0.035VR 0.088 0.050 0.045 0.043 0.038 0.043 0.050 0.050 0.043

MEANS 0.047 0.035 0.035 0.031 0.029 0.034 0.031 0.030 0.0341WN=Western North, WS=Western South, CR=Central Region, AR=Ashanti Region, BA=Brong Ahafo Region, ER=Eastern Region.VR=Volta Region, Fert = fertilized, Unfert = unfertilized. Limit of Quantification (LOQ) = 0.005, SEM = 0.002. Regional mean soil values werecalculated using data points from all sites for each regions (n=10) except Volta Region (VR) where n=4].

Cd. This indicates that cocoa powder sold as a singleproduct to the final consumer (i.e. drinkable cocoapowder) would contain 0.269 µg/g Cd. Since Cd isassociated with the fat free cocoa solid, cadmium contentin raw cocoa powder is the same as the Cd content in thebeans (WHO, 2015). Thus, the amount of Cd in cocoapowder, if consumed as beverage, constitutes the highestintake level for any consumer of a cocoa product. InGhana, unsweetened cocoa powder is recommended aselixir for lowering high blood pressure and alleviatingmalaria parasitaemia (Addai, 2010; Winter, 2010) andmany adult Ghanaians drink cocoa powder beverageliberally. Assuming a 70 kg man drinks unsweetenedcocoa powder beverage three times a day and at eachintake consumes one teaspoonful, this translates to about2 g cocoa powder if teaspoon is scooped flat asrecommended (Addai, Pers. com) or 4 g if teaspoon isheaped. This converts to 1.6-3.2 µg Cd/day or 11.2-22.4µg Cd/week depending on consumption rate. Thetolerable weekly intake (TWI) recommended by JECFA is5.8 µg/kg body weight (JECFA, 2013). According to theJECFA evaluation, the 70 kg man should safely consume406 µg Cd per week. Thus, the recommended dose fornatural cocoa consumption in Ghana is about 36-18-foldless. On the other hand, going by the 2.5 µg/kg bw

proposed by the EC in Regulation No. 1881/2006 (EU,2014), this amount (175 µg/wk) is again 16-8-fold higherthan can be ingested via the recommended dose (11.2-22.4 µg Cd/wk) in Ghana. This simplified analysisindicates that cocoa beans from Ghana may not poseany health risk with respect to Cd accumulation onaccount of daily ingestion because the recommendedcocoa intake delivers Cd levels that are far below theprovisional tolerable weekly intake levels determined byCodex or that proposed by the EU. Hence, cocoa beansfrom Ghana are safe, so far as Cd levels are concerned.

Conclusion

Cadmium concentration in cocoa beans and cocoa soilsin Ghana were determined and found to be very lowrelative to levels found in other countries, particularlyPeru and Venezuela. Mean Cd concentration in cocoabeans was 0.269 mg/kg; a simple calculation relatingconsumption rate in Ghana to internationallyrecommended exposure rates indicated that cocoaproducts from Ghana pose no health risk to theconsuming public.

ACKNOWLEDGEMENT

We are grateful for Technical support from Very Rev Agyenim Boateng and staff of Quality Control CompanyLtd. for the nationwide sample collection, and Devine

Addo, for Atomic Absorption Spectroscopic analysis. Wealso thank Mr. Francis Aneani for the statistical analysisand Prof. FK Addai for critically reading through themanuscript. This paper is published by permission of theExecutive Director of the Cocoa Research Institute oGhana.

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