Environ Monit Assess(2009)156:303–306
DOI10.1007/s10661-008-0485-1
Trace metal levels in fruit juices and carbonated beverages in Nigeria
Akan B.Williams·Olusegun O.Ayejuyo·
Adekunle F.Ogunyale
Received:25December2007/Accepted:23July2008/Published online:13August2008©Springer Science+Business Media B.V.2008
Abstract Trace metal levels in selected fruit juices and carbonated beverages purchased in Lagos, Nigeria were determined using atomic absorption spectrophotometer(Unicam model969)equipped with SOLAAR32windows software.Fruit juices analysed were grape,pineapple,apple,orange, lemon juices and their brand names were used. Some carbonated drinks were also evaluated for metal levels.Trace metals investigated were Cr, Cu,Pb,Mn,Ni,Zn,Sn,Fe,Cd and Co.Trace metal contents of fruit juices were found to be more than the metallic contents of carbonated beverages.Pb level in the fruit juices ranged from 0.08to0.57mg/l but was not detected in the carbonated drinks.Concentrations of Pb in lemon juice a
nd Mn in pineapple juice were relatively high.Cd and Co were not detected in the selected juices and beverages.Additionally,Pb,Cu,Cr and Fe were not detected in canned beverages but A.B.Williams(B)
buchiDepartment of Chemistry,Covenant University,
P.M.B.1023,Ota,Ogun State,Nigeria
e-mail:akanwills@yahoo
O.O.Ayejuyo
Department of Chemistry,University of Lagos,
Akoka,Nigeria
A.F.Ogunyale
Department of Chemistry,Lagos State University,
Ojo,Nigeria were present in bottled beverages.However,the metal levels of selected fruit juices and carbonated beverages were within permissible levels except for Mn in pineapple juice and Pb in lemon
juice.
Keywords Carbonated beverages·Fruit juices·Nigeria·Trace metals
Introduction
Many Nigerians drink fruit juices and carbonated beverages.The increasing intake of these drinks by a sizeable population in the country is largely attributed to the increase in fast food restaurants and snack bars,the growing preference for non-alcoholic drinks due to religious beliefs,increase in prices of alcoholic drinks and preference for imported goods by most Nigerians.The gastroin-testinal tract of humans is exposed to various en-vironmental pollutants including trace metals that contaminate food and water and may have toxic effects on the body.Studies indicate that some metals act as catalysts in the oxidative reactions of biological macromolecules,hence the toxicities associated with these metals might be due to ox-idative tissue damage(Ercal et al.2001).
Reasons could be advanced for the toxicity of trace metals in humans.For instance,the metabolism of the toxic metal may be similar
to metabolically related essential ones.Such is the case with effects of Pb and Ca in the cen-tral nervo
us system and Pb,Fe and Zn in heme metabolism.Human cells that are involved in the transport of metals such as gastro-intestinal, liver or renal tubular cells are particularly sus-ceptible to toxicity(Jarup2003).Factors such as age,diet,interactions and exposure to other toxic metals influence the toxicity levels of metals in humans(Peakall and Burger2003).Children and the elderly are believed to be more susceptible to toxicity from metallic exposure.Trace metals are present in foods in amounts below50ppm and have some toxicological or nutritional signif-icance.While some inorganic elements such as Na,K,Ca,P are essential for man,elements like Pb,Cd,Hg,As are found to cause deleterious effects even in low levels of10–50ppm.Although Fe,Cu,Zn are found to be necessary in certain quantities in foods,the same elements can cause ill effects when consumed at higher levels.Hence, determination of both major and trace levels of metal contents in food is important for both food safety and nutritional considerations(Ministry of Health and Family Welfare2005).Trace metals are classified into three classes based on their effects on life.The essential nutritive metals are Co,Cu,Fe,I,Mn and Zn.However,elements such as Cu and Zn have emetic action when ingested in higher amounts.The non-nutritive non-toxic metals which are not harmful when present in amounts not exceeding100ppm include Al,B, Cr,Ni and Sn.However,the increasing chromium intake calls for concern.Nigerian consumers may be exposed to higher levels considering the rel-ative contribution of the element to the diet by beverages alone(Maduabuchi et al.2007).The non-nutritive toxic metals which are known to ha
ve deleterious effects even at amounts below 100ppm are As,Sb,Cd,F,Pb,Hg and Se (Ministry of Health and Family Welfare2005). For example,arsenic exposure induces cardiovas-cular diseases,developmental abnormalities,neu-rologic and neurobehavioral disorders,diabetes, hearing loss,hematologic disorders and various types of cancer(Tchounwou et al.2004).
Utilization of trace metals by humans influence the potential for health effects through environ-mental transport and by altering the biochemi-cal form of the element(WHO1992).Naturally, metals are redistributed in the environment by both geologic and biologic cycles(Goyer and Thomas2001).Rain water dissolves rocks and ores and physically transports material to streams and rivers,adding and deleting from adjacent soil and eventually to the ocean to be precipi-tated as sediment or taken up in the rain water to be relocated elsewhere on earth(Forner and Wittman1993).The biologic cycles include bio-concentration by plants and animals and incorpo-ration into food cycles.
Food is a major source of human exposure to metals.Potential sources of human exposure include consumer products and industrial waste as well as the working environment.Cumulative poisoning due to ingestion of food containing met-als such as lead and arsenic over a long period do occur.Some metals have detrimental effects on the quality or nutritive value of food.For example,copper causes off-flavour in milk and dairy products and tend to destroy vitamin C in fruit products.It is known that fruit jui
ces and car-bonated beverages contain trace metals.There-fore,the trace metal contribution of juices and beverages cannot be neglected(Onianwa et al. 2000).Less attention appears to be given to de-termination of trace metals in fruit juices and carbonated beverages.This investigation aims at determining trace metal content in imported fruit juices packaged in pouches and carbonated
Table1Trace metal content(ppm)of fruit juices
Fruit type Cr Cu Pb Mn Ni Zn Sn Cd Co Grape0.08ND0.080.800.200.39 1.80ND ND Pineapple ND ND0.0915.000.290.900.45ND ND Apple ND0.260.080.530.020.17 1.90ND ND Orange ND0.020.080.450.060.190.59ND ND Lemon0.05ND0.570.230.020.93 1.85ND ND
Table2Trace metal content(ppm)of carbonated beverages in glass containers
Beverage type Cu Mn Ni Zn Sn Fe Cd Co Beverage10.080.010.020.070.020.62ND ND Beverage20.190.010.020.020.020.44ND ND Beverage30.290.010.020.050.020.67ND ND Beverage40.140.010.020.020.020.21ND ND Beverage50.330.010.020.150.020.49ND ND
beverages in cans and glass bottles in Nigeria. The study serves as a guide in avoiding bio-accumulation of heavy metals in human system considering the peculiarity of environmental pol-lution being experienced in industrial and urban centres of Nigeria.
Materials and methods
The fruit juice samples were purchased in Lagos at Oke Arin,Oyingbo,Apongbon and Ikeja mar-kets.Bottled(glass)and canned samples of the same brand of carbonated drinks were obtained and analysed.The brand names of the imported fruit juices were labelled brand1,brand2,brand3, brand4and brand5respectively.The carbon-ated beverage samples analysed were similarly la-belled beverage1,beverage2,beverage3,beverage4 and beverage5.Trace metal levels in selected fruit juices and carbonated beverages were determined using atomic absorption spectrophotometer (Unicam model969)equipped with SOLAAR 32windows software.A multi-metal standard solution of nine(9)metals was prepared to give the following concentrations:Cu 1.0ppm,Zn 0.2ppm,Ni0.2ppm,Cr0.2ppm,Mn0.05ppm, Pd0.5ppm,Cd0.5ppm,Co0.2ppm,Sn0.2ppm.
In fruit juices,large particles werefirst removed by centrifuging and interference from sugar was compensated for by using standard method of additions.Fruit juices were centrifuged for15min at4,500rpm to obtain pulp free liquid.Aliquots0, 1,2and3ml of the multi-metal standard solution were added to100ml volumetricflasks containing 3,2,1and0ml of distilled water respectively and diluted to100ml with clear juice.The prepared samples were aspirated directly into the atomic absorption spectrophotometer.Carbonated bev-erages were analysed after the removal of car-bon(IV)oxide by aer
ation.Four100ml aliquot of carbonated drinks were pipetted into250ml beakers containing0,1,2and3ml of multi-metal standard solution respectively.After heating on a hot plate until the volume was reduced to75ml, the samples were cooled and diluted to100ml and the prepared samples were aspirated directly into the spectrophotometer.
Results and discussion
Levels of Pb,Cd,Cu and Zn less than0.05,0.05, 0.30–1.10and1.30–8.6mg/l have been reported (Food and Drug Directorate1990).Concentra-tions up to2.10and150mg/l for Mn and Sn re-spectively have been found in citrus juices.In this study,trace metal content of selected fruit juices, carbonated beverages in glass containers and cans are highlighted in Tables1,2and3.Trace metal levels of fruit juices were higher than metallic levels of carbonated beverages which were com-paratively low.This implies that it is relatively safer to consume carbonated beverages compared
Table3Trace metal content(ppm)of carbonated beverages in cans
Beverage type Cu Mn Ni Zn Sn Fe Cd Co Beverage1ND0.010.02 3.300.02ND ND ND Beverage2ND0.010.020.080.02ND ND ND Beverage3ND0.010.020.080.02ND ND ND Beverage4ND0.010.02 2.050.02ND ND ND Beverage5ND0.010.02 6.800.02ND ND ND
to fruit juices.Cd and Co were not detected in all selected juices and beverages and Pb was not detected in the carbonated drinks.Concentrations of Pb in lemon juice and Mn in pineapple juice were relatively high.This relatively high concen-tration of Pb in lemon juices and Mn in pineapple juice indicates the need for a more detailed study of these juices.Zn contents of canned beverages were much higher than that found in glass bottled beverages.Pb,Cu,Cr and Fe were not detected in canned beverages but were detected in glass con-taining beverages.Bio-accumulation of trace met-als do have serious health implications in human beings.For example,high level of Pb has been reported to be responsible for anemia and affect central nervous system,causing mental retardness and convulsion in childhood(Ademoroti1996). High level of Mn causes psychiatric disorder in-cluding difficulty in walking,speech and compul-sive behavior such as running,fighting and singing. However,the metal levels of selected fruit juices and carbonated beverages were within the permis-sible limits stipulated by Standard Organization of Nigeria and Codex Alimentarius(IARC1987) except for manganese(15.00ppm)in pineapple juice and lead(0.57ppm)in lemon juice. References
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