Lead, cadmium and nickel in chocolates and candies from suburban ...

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Journal of Food Composition and Analysis 18 (2005) 517–522

Original Article

Lead, cadmium and nickel in chocolates and candies from suburban areas of Mumbai, India Sudhir Dahiya*, Rupali Karpe, A.G. Hegde, R.M. Sharma Environmental Studies Section, Health Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India Received 18 July 2003; received in revised form 11 May 2004; accepted 14 May 2004

Abstract Nickel, lead and cadmium contents were determined in 69 different brands of chocolates and candies available in local markets of suburban areas of Mumbai, India. The majority of these chocolates and candies are made mainly from cocoa, milk solids, dry fruits, fruit flavours and sugar. Out of 69 brands of chocolates and candies analysed, 23 were cocoa-based, 22 milk-based and another 24 were of fruit flavour and sugar-based. Cadmium level ranged from 0.001 to 2.73 mg/g with an average of 0.105 mg/g. Nickel ranged from 0.041 to 8.29 mg/g with an average of 1.63 mg/g and lead level ranged from 0.049 to 8.04 mg/g with an average of 0.93 mg/g. Cocoa-based chocolates are found to have higher contents of the analysed heavy metals than milk-based chocolates, fruit flavour- or sugar-based candies. r 2004 Elsevier Inc. All rights reserved. Keywords: Lead; Nickel; Cadmium; Chocolate; Cocoa; Candies

1. Introduction The future of any nation depends on the health, prosperity and progress of the forthcoming generation. In the present era of industrialization and development, one concern should be the health of the future generation. Children are the most vulnerable age group to any kind of contamination in the food chain. Chocolates and candies/toffees are the favourite food items of children and are often presented to them as token of love and affection from their parents and relatives. *Corresponding author. E-mail address: [email protected] (S. Dahiya). 0889-1575/$ - see front matter r 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.jfca.2004.05.002

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Consumption of chocolates and toffees is not limited to a part of society. There are many types of locally made toffees and chocolates available in the market at a cheaper price than known brands. Out of these, only 60–70% have food labels listing ingredients on the wrappers. The most common ingredients listed are sugar, liquid glucose, milk solids, cocoa solids, hydrogenated vegetable oil (HVO), vegetable fats, malt extract, soya solids, permitted emulsifier, salts, buffering agents, permitted stabilizer, sodium bicarbonate, cocoa butter, wheat flour, edible starches, vegetable oil, added flavour, soya lecithin, yeast and flour improvers, etc. Out of the abovementioned ingredients, milk solids, cocoa solids, cocoa butter, hydrogenated vegetable oil, vegetable fats, permitted emulsifier, buffering agents and permitted stabilizer may be the source of nickel, lead and cadmium contamination.

Toxicity of nickel, lead and cadmium Nickel in chocolates made the news headlines in the early 1990s. Nickel in various types of chocolates and toffees was reported by Selavpathy and Sarala Devi (1995) with a range of 0.15– 3.55 mg/g with a mean of 0.88 mg/g. Nickel is the main known contaminant resulting from the manufacturing process of chocolate, when its hardening is done by hydrogenation of unsaturated fats using nickel as catalyst. Cocoa butter is another important ingredient which may contain high concentrations of nickel (Selavpathy and Sarala Devi, 1995). Some other pathways for nickel to toffees are raw materials, their processing and canning for transportation and storage in nickel containers (Melsallam, 1987). Nickel at trace amount may be beneficial as an activator of some enzyme systems (Underwood, 1977). At higher levels, it accumulates in the lungs and may cause bronchial haemorrhage. Other symptoms include nausea, weakness, dizziness, etc (Nielson, 1977). However, nickel compounds are not currently regarded as either human or animal carcinogens (WHO, 1984), but the possibility that Ni can act as a promoter has been reported (WHO, 1991). Cadmium toxicity came in the headlines after the Itai-Itai disease was found to be caused by high intakes of cadmium in Japan. When cadmium is ingested in excess amounts, it induces toxicity symptoms like gastrointestinal pains, nausea, respiratory distress, diarrhoea, impaired reproductively, kidney damage and hypertension (Schroeder, 1965; Underwood, 1977; Somer, 1974). Ingested lead accumulates in the different organs of the body. The adverse effects associated with lead are under-development of central nervous system in the foetus and the newborn babies. It is especially dangerous because it can damage the brain and peripheral nerves. Lead affects everyone, but children are at a higher risk as they are still at growing stage. This may disrupt the junction of mitochondria in the developing brain. It is important for energy production within a neuron, and a change in their function may damage the cell. Lead may also affect brain function by interfering with neurotransmitter release and synapse formation (Mo et al., 1988). Exposure to lead has been associated with reduced IQ, learning disabilities, slow growth, hyperactive, antisocial behaviour and impaired hearing. Lead is known to damage the kidney, liver and reproductive system, basic cellular processes and brain function (US EPA, 1984). This work has been done in view of the toxic effects of these heavy metals and their presence in chocolates, which can be deleterious to children. The present study reports concentration of lead, nickel and cadmium in the chocolates and candies available in suburban areas of Mumbai, India.

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2. Materials and methods 2.1. Sample preparation and analysis A total of 69 different brands of chocolates and candies were procured from the different suburban areas of Mumbai. Two different batches of the same brand of chocolates packed on different dates were purchased to observe the variation in the elemental contamination levels of the products. All the chemicals used were AR grade. Standard stock solutions were prepared from lead nitrate (Pb(NO3)2) for lead, from nickel sulphate for nickel, and from cadmium sulphate for cadmium, dissolved in nitric acid. These stock solutions were standardized with the primary standard Certified Reference Material (Hay V-10). Demineralized water from Millipore Elix-3 was used for all dilutions and preparation of solutions. After weighing (milk and cocoa based 5 g and sugar based 10 g) the chocolates were taken for wet digestion with mixture of nitric acid (HNO3) and perchloric acid (HClO4) in the ratio 3:1 for decomposition. After gentle heating for 16 h, colourless solution was obtained which was evaporated to near dryness. On completion of digestion and adequate cooling of residues, solutions were made up to 10 mL with 0.04 mol/L nitric acid. All the chocolates/candies samples were processed and digested in triplicate. The variation among the elemental content in these replicates was within 78%. One blank was always prepared with each batch. Quality assurance of trace metals analysis was done by analysing Certified Reference Material (CRM) Hay V-10, supplied by Analytical Quality Control Services (AQCS), International Atomic Energy Agency (IAEA). The results agree within 77% of the certified values (Table 1). The determination of elemental concentrations by Atomic Absorption Spectrophotometer model GBC (Avanta PM) in all the digested solutions was made in triplicate and percentage of relative standard deviation (%RSD) in the concentrations of analytical replicates was 72%. All the measurements were made under optimization of the parameters mentioned in Table 2. The deuterium lamp background correction was applied for measurements carried out with respective hollow cathode lamp.

3. Results and discussion The range and arithmetic mean concentrations of cadmium, nickel and lead in the different types of chocolates and candies are given in Table 3 as averages of three replicates of the

Table 1 Concentrations of trace metals in certified reference material (Hay V-10) from IAEA Trace metals

Pb Cd Ni

Concentration (mg/g) Certified values

Observed values

1.6 (0.8–1.9) 0.03 (0.02–0.05) 4.0 (3.8–4.9)

1.6 (1.45–1.73) 0.027 (0.02–0.03) 3.8 (3.7–4.2)



Table 2 Parameters for the elemental measurements by AAS Element

Wavelength (nm)

Band width (nm)

Flame

Sensitivity (mg/mL)

Cadmium Nickel Lead

228.8 232.00 217.00

0.5 0.2 1.0

Air–C2H2 Air–C2H2 Air–C2H2

0.009 0.04 0.16

Table 3 Lead, nickel and cadmium concentrations in the different types of chocolates Chocolates analysed Type Cocoa based Milk based Sugar-based candies Total

n 23 22 24 69

Lead concentration (mg/g)

Nickel concentration (mg/g)

Cadmium concentration (mg/g)

Range 0.236–8.04 0.234–2.62 0.049–0.97 0.049–8.04

Range 0.049–8.290 0.137–8.288 0.041–1.150 0.041–8.230

Range 0.010–2.730 0.010–0.852 0.001–0.027 0.001–2.730

Mean 1.915 0.613 0.269 0.927

Mean 2.763 1.739 0.434 1.626

Mean 0.244 0.071 0.005 0.105

individual chocolates/candies. Coefficient of variation in the nickel concentration ranged from 0.8% to 30.2% with an average of 1278% in the chocolates of same brands from different batches for all the 69 brands analysed in this study. The variation in the chocolates from different batches was high for lead with coefficient ranging from 2.8% to 45.6% with an average of 26714%. In case of cadmium, the variation in the chocolates of the same brand was at a minimum, ranging from 0.6% to 12.4% with an average of 674%. The variations are mainly due to heterogeneity in the samples as all the chocolates were taken from different batches rather than to instrument uncertainties, which are minimal in the analysis as instrumentation measurements were made in triplicate. A recovery study for analytical procedure was carried out by spiking some chocolates with standard solutions and comparing them with unspiked samples. Recoveries of all the metals were found to be more than 85%. From a preliminary survey of a small group of children, it was found that cocoa-based chocolates are their first choice and that they eat daily 2–3 chocolates. The weight of chocolates varies from 4 to 40 g, but the majority of the chocolates weight about 20 g. As chocolates are not a regular food item, ingestion rate of 20 g/day is taken for all the metal intake estimation in this study. Chocolates were divided into three categories, namely cocoa- , milk- and sugar-based candies, on the basis of their ingredients and labelling name. The range and average concentrations of lead, nickel and cadmium in all three types of chocolates are given in Table 3. Lead has been a well-known contaminant in all types of food items from the early phase of food industrialization in different parts of the world. A possible association between increased lead content in blood and reduced intelligence quotient has been substantiated and a lower threshold could not be set (FAO/WHO, 1993). A provisional tolerable weekly intake (PTWI) has been

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established at 25 mg/kg body weight (FAO/WHO, 1993), which is equal to 375 mg per week for a child having a body weight of 15 kg. The average lead concentration in cocoa-based chocolate is 1.92 mg/g as shown in Table 3. A child who eats a 20 g chocolate daily on an average basis will ingest 270 mg of lead in a week. The lead content from the chocolate itself will exceed 70% of the PTWI and contributions from other sources will further increase the intake. The average concentration of lead in milk-based chocolates is almost 30% of the cocoa-based chocolates (Table 3). Sugar-based and other candies have less than 15% lead content in comparison to the cocoa-based chocolates. The dietary intake of nickel does not lead to any health risk in the general population. Although troublesome to some sensitized individuals, a tolerable oral intake of nickel has not been established. Like lead, nickel levels in cocoa chocolates were higher than in the milk-based chocolates and sugar or fruit flavoured candies. The dietary contribution of nickel has been reported to range from 200 to 900 mg/day (Schroeder, 1965; Myron et al., 1978; Clemente et al., 1980; Smart and Sherlock, 1987; Nielson and Flyvholm, 1984; Larsen et al., 2002). In Indian foods the nickel content reported by Krishnamurti and Pushpa (1991) is much higher (240– 3900 mg/day). The contribution of nickel content from chocolates will not affect the daily intake as the daily intakes from chocolate will be 55.26 mg/day (cocoa-based), 34.78 mg/day (milk-based) and 8.68 mg/day (sugar-based candies), if 20 g of chocolate is taken by any individual (Table 3). Thus, the nickel intake from chocolate can be considered as less harmful. Cadmium accumulates in the body mainly in the kidneys and the liver, having a half-life of several decades. The toxic effect occurs in the kidneys and may lead to proteinuria. PTWI has been established at 7 mg/kg of body weight (FAO/WHO, 1989). For a child with a body weight of 15 kg, the PTWI would be 105 mg/week. If someone ingests 20 g cocoa-based chocolate daily, it will contribute approximately 33.5% of PTWI. Because chocolates are not the major food items the cadmium intake from other sources like food and water is likely to exceed PTWI for children. In case of milk-based and sugar candies the intake of cadmium is much less than cocoa-based chocolates (Table 3). There are no well-defined limits for these elements in chocolates in most of the countries except a few. The maximum level of lead in chocolate defined by FAO/WHO (2001) is 1 mg/kg. In Poland, the Polish national standard for lead in chocolates is 0.30 mg/kg and for cadmium 0.05 mg/kg (FAO/WHO, 2001). According to these limits laid down by the Poland regulatory agency, 42 chocolates out of 69 contained concentrations higher than the authorized limits. In case of cadmium, 19 chocolates contained more than the prescribed concentration level. The sources of contamination for these metals are mainly the raw materials used, manufacturing processes and leaching of these metals from the vessels in which they are stored, especially the ones still in use that have lead shouldering seals. Processing of chocolates is done in steel containers from which nickel contamination is possible in addition to the contamination from the catalyst used in preparation of the HVO.

4. Conclusions The concentrations of all analysed elements were highest in the cocoa-based chocolates followed by milk-based and sugar- and fruit flavour-based chocolates. The higher concentration



of these elements in the chocolates is due mainly to their higher contents in the raw materials such as cocoa beans, cocoa solids, and cocoa butter. The daily intake of cocoa-based chocolates must be reduced to keep the PTWI for lead and cadmium within the prescribed limits. Raw materials having lower content of these elements should be used to decrease the concentrations of these metals in chocolates. Acknowledgements The authors are thankful to Dr. V. Venkat Raj, Director, Health Safety and Environment Group, Bhabha Atomic Research Centre, Trombay, for valuable support and encouragement throughout this study. References Clemente, G.F., Cinga Rossi, L., Santaroni, G.P., 1980. In: Nriagu, J.O. (Ed.), Nickel in Environment. Nickel in Foods and Dietary Intake of Nickel. John Wiley and Sons, New York, pp. 493–498. FAO/WHO, 1989. Toxicological Evaluation of Certain Food Additives And Contaminants. WHO Food Additive Series, 24, Geneva. FAO/WHO, 1993. Evaluation of Certain Food Additives and Contaminants. WHO Technical Report Series, 837, Geneva. FAO/WHO, 2001. Draft Standards for Chocolates and Chocolate products. Joint FAO/WHO Standards Programme. CODEX Committee on Cocoa Products and Cocoa Chocolates, 19th Session, 3–5 October 2001, Fribourg, Switzerland, CX/CPC 01/3. Krishnamurti, C.R., Pushpa, 1991. Toxic Metals in the Indian Environment. Tata McGraw-Hill, New Delhi, p. 161. Larsen, E.H., Andersen, N.L., Moller, A., Petersen, A., Mortensen, G.K., Petersen, J., 2002. Monitoring the contents and intake of trace elements from food in Denmark. Food Additives and Contaminants 19 (1), 33–46. Melsallam, A.S., 1987. Heavy metal contents of canned orange juice. Food Chemistry 26 (1), 47–58. Mo, S.C., Choi, D.S., Robinson, J.W., 1988. A study of the uptake by duckweed of aluminium, copper and lead from aqueous solution. Jounal of Environmental Science and Health 23 (2), 139–156. Myron, D.R., Zimmertman, T.J., Shuler, T.R., Klevay, L.M., Lee, D.E., Nielson, F.H., 1978. Intake of nickel and vanadium by humans. A survey of selected diets. American Journal of Clinical Nutrition 31 (3), 527–531. Nielson, F.H., 1977. Nickel toxicity. In: Advances in Modern Toxicology, Vol. 2 (Toxicology of Trace Elements). Hemisphere Publishing Corporation, Cambridge, pp. 129–146. Nielson, F.H., Flyvholm, M., 1984. Risk of high nickel intake with diet. In: Nickel in Environment. Proceedings of the Joint Symposium, Lyon 8–11 March 1983, Lyon International Agency for Research on Cancer, (IARC Scientific Publication No. 53), pp. 333–338. Schroeder, H.A., 1965. Cadmium and hypertension. Journal of Chronic Diseases 18, 647–651. Selavpathy, P., Sarala Devi, G., 1995. Nickel in Indian chocolates (toffees). Indian Journal of Environmental Health 37 (2), 123–125. Smart, G.A., Sherlock, J.C., 1987. Nickel in the food and diet. Food Additives and Contaminants 4 (1), 61–71. Somer, E., 1974. Toxic potential of trace metals in foods,—a review. Journal of Food Science 39, 215–217. Underwood, E.J., 1977. Trace Elements in Human and Animal Nutrition, 4th Edition. Academic Press, New York. US EPA, 1984. Cost and benefit of reducing lead in gasoline. Draft Final Report, Office of Policy Analysis, US EPA 230-03-84-005, Washington, DC. WHO, 1984. Guidelines for Drinking Water Quality, Vol. II. Health Criteria and other supporting information, Geneva, p. 126. WHO, 1991. International Programme on Chemical Safety. Environmental Health Criteria, Vol. 108, Geneva, p. 286.