Assessment of trace elements in soumbara seasoning from the Abidjan Market (Côte d'Ivoire)

Abstract

This study aims to assess the level of contamination by trace elements (TMEs) in soumbara sold on markets (Abidjan Cty) to evaluate the risks of exposure for consumers. Seventy-five samples taken from the markets (Abobo market, Adjamé market, Cocody market, Treichville market, and Port-Bouët market) were analysed using inductively coupled plasma optical emission spectrophotometry (ICP-OES) from Spectro Arcos (USA). The results showed the presence of lead, cadmium, chromium, iron, manganese, copper, zinc, nickel, and cobalt in the samples analysed. The average lead content varied from (0.012±0.011) mg/kg (in soumbara sold on the Adjamé market) to (0.015±0.014) mg/kg (in soumbara sold on the Cocody market). The cadmium content was (0.019±0.012) mg/kg in soumbara sold on the Adjamé market. In soumbara sold on the Port-Bouët market, the content was (0.015±0.012) mg/kg. The average manganese content in soumbara sold on the Treichville was (1.663±1.447) mg/kg. The average iron, manganese, copper, zinc, and nickel content exceeded the required General Standard for Contaminants and Toxins in Food and Feed from Codex Alimentarius (CXS 193-1995), with the other trace elements present in trace amounts. However, the Risk Quotient (AHM/DHTP) for all the trace elements was less than 1. Consumption of soumbara sold in Abidjan markets would not present a health risk to consumers.

Keywords:
Abidjan city market; Risk; Soumbara; Trace elements; ICP-OES; Cote d’Ivoire

HIGHLIGHTS

The average iron, manganese, copper, zinc, and nickel content exceeded the required General Standard for Contaminants and Toxins in Food and Feed from Codex Alimentarius (CXS 193-1995)

The risk quotient is less than < 1

Producers must be trained in good production and hygiene practices to prevent product contamination

1 Introduction

Soumbara is a traditional fermented food commonly consumed in West and Central Africa. Fermented néré grains are ground into powder to obtain soumbara (Mertz et al., 2001; Yagoub et al., 2004). It is mainly used as a condiment to enhance the flavour of foods. One of the most important properties of soumbara is its ability to reduce blood pressure (Gutierrez, 2000; Diawara & Jakobsen, 2004). This property is the main reason why this food is widely consumed, as it is recommended for people suffering from high blood pressure (Gutierrez, 2000). This pod-shaped food is consumed not only for its sweet, floury pulp, but also for its seeds, which are used to prepare fermented condiments in West Africa. These dried seeds are among the hardest (Razzavi et al., 2007). In Côte d'Ivoire, as in most West African countries, soumbara is widely consumed by the rural population. It is used to prepare dishes to enhance the flavour of sauces accompanying cereal-based dishes such as rice, millet, sorghum, maize, etc. (Compaoré et al., 2013;Oguntoyinbo et al., 2007). Soumbara is also an important source of protein for low-income families, and it contains 28% to 48% protein (Souare, 2022). However, this food is processed traditionally, without any safety procedures or standards, which means that the quality of soumbara varies. With the rise of illegal gold panning in the north of the country, environmental pollution is on the increase. Illegal gold miners use chemicals that do not comply with environmental standards. The Néré tree (Parkia biglobosa) that produces the fruit used to make soumbara is found in the wild (Simon et al., 2016). Local people generally only have what nature provides to satisfy their multiple needs for nutrition and traditional care (Ayihouenou et al., 2016). Currently, the concern raised by emissions of trace metal elements (TMEs) is mainly related to health issues. These concerns are associatedwith the persistence of TMEs in the natural environment, their bioaccumulative nature in the environment, and their effects on health (Stenbeck, 2004). A large number of contaminants of various origins and types can contaminate soils and the environment and enter the food chain. Once transferred to humans via the digestive tract, they combine with organic sulphur compounds in our bodies to cause serious disorders, including brain damage (Picot, 2003), in the short or long term. Food is the main route of exposure to many of these metals in the absence of any specific source. The food crises caused by environmental pollution have led consumers to demand the right to food safety (Laurent et al., 2005). Therefore, food contributes to the increase in trace elements in the body (Miranda et al., 2005). In humans, trace elements are concentrated in tissues mainly through the food chain (Anyanwu et al., 2018). Therefore, trace elements are absorbed directly by ingestion or inhalation, and then concentrate in the various parts of the human body, leading to chronic or acute effects on human health (Were et al., 2008). Trace elements pollution contributes to food insecurity and increases the risk of diseases linked to contamination, such as liver and kidney disease, cardiovascular disease, cancer, pneumonia, and anaemia (Anyanwu et al., 2018; Lauwerys et al., 2007; Testud, 2005). Hence, the setting by the competent bodies of standards and quantitative safety limit values (toxicological reference values) above which health would be threatened. Evaluating the level of contamination of these trace elements in terrestrial organisms is therefore a way of assessing the chemical quality of the environment and foodstuffs. This study aimed to assess the level of trace metal (TME) contamination in soumbara sold on markets in order to evaluate the risks of consumer exposure.

2 Material and methods

The plant material consisted of soumbara sold on the markets of Abidjan in Côte d'Ivoire (Figure 1).

Figure 1
Soumbara sold in markets in Abidjan, Côte d’Ivoire.

2.1 Study sites

Markets were chosen and selected according to population density and income. The study was conducted in five large soumbara markets in the city of Abidjan (Abobo market, Adjamé market, Cocody market, Treichville market, and Port-Bouët market). Abobo and Adjamé markets were chosen because of the high density of the low-income population. The Cocody market is home to the majority of high-income earners. Treichville and Port-Bouët markets were selected because of their low-income populations, but also because they are home to a large sub-regional population.

2.2 Sampling

Five (5) markets in the city of Abidjan (Cocody market, Abobo market, Treichville market, Adjamé market, and Port-Bouët market) were selected. In each market, five (5) soumbara sellers were selected at random. For each sample, 500 g of soumbara were taken from each vendor. Three (3) samples were taken. A total of 75 samples were taken for this study. Once collected, the samples were sent to the laboratory within 4 hours for analysis.

2.2.1 Determination of the optimum conditions of ICP-OES for trace elements

Before trace element quantification, conditions for sample preparation and for ICP-OES Arcos (USA) analysis were carefully chosen in order to define the optimal settings for the analysis. These conditions are shown in Table 1. After optimization, the selected method was demonstrated to be the most selective and sensitive. Quantification limits were obtained through the signal/noise (10×S/N) method. The correlation coefficient(R2), detection limits (LOD), and quantity limits (LOQ) of each element are shown in Table 2. According to these measurements, it was seen that the sensitivity of the method was high, and the detection limit could be used easily in the quantitative analysis of metals with very low concentrations.

Table 1
The operating parameters of the determination of trace elements by ICP-OES.

Instrument	Spectro Arcos
Viewing height (mm)	12
Wavelength	Nm
Replicates	3
RF Power (W)	1450
Spray chamber	Cyclonic
Nebulizer	Modified Lichte
Nebulizer flow (L/min)	0.8
Plasma Torc	Quartz, fixed, 3.0 mm injector tube
Replicate read time	50 s per replicate
Plasma Gas Flow (L/min)	13
Auxiliary Gas Flow (L/min)	0.7
Sample aspiration rat(mL/min)	2
Sample Pump Rate (rpm)	25

Table 2
Figures of merit of the ICP-OES method showing correlation coefficient (R2), Limits of Detection (LOD), and Limits of Quantitation (LOQ) of each element.

Elements	R2	LOD (mg/L)	LOQ (mg/L)
Mn	0.9950	0.015	0.065
Fe	0.9991	0.013	0.036
Cu	0.9995	0.004	0.007
Pb	0.9994	0.002	0.004
Cr	0.9997	0.0004	0.0015
Co	0.9960	0.015	0.050
Ni	0.9999	0.0003	0.0011
Zn	0.9997	0.007	0.020
Cd	0.9998	0.004	0.016

2.2.2 Analytical performance

Validation of the proposed method was carried out using certified reference material NIST-SRM 1515-Apple Leaves. The comparison of the metal content of the certified reference material with the values measured by our method is shown in Table 3. Our method demonstrated high accuracy, allowing us to analyse the metal amounts in our real sample.

Table 3
The results of the analysis with microwave digestion procedures of NIST SRM 1515 Apple Leaves certified reference material (µg/g), N = 4.

Elements	Certified value	Microwave digestion	RSD (%)
Fe	83 ± 5	81.0 ± 4.6	3.41
Cu	5.64 ± 0.24	5.56 ± 0.27	2.42
Pb	0.470 ± 0.024	0.450 ± 0.007	8.16
Ni	0.91 ± 0.12	0.88 ± 0.11	10.3
Zn	12.5 ± 0.3	12.1 ± 0.6	11.2

2.3 ICP-OES analysis of soumbara samples

The dried soumbara samples were brought to a fixed weight in the oven. The dried soumbara samples were washed and dried at 100 °C for 48 hours. The cleaned samples were ground in the grinder. Before determining the number of metals, a microwave digestion procedure was performed using a microwave digestion system (SH230N Heavy Metal Digestor) to achieve total digestion in a short time, avoiding metal loss through volatilisation and minimising the amount of acid added. The digestion procedure was as follows: 0.5 g of the sample was placed in a polytetrafluoroethylene (PTFE) digestion vessel (100 ml), 15 ml of nitric acid (HNO₃,65%), and 20 ml of hydrogen peroxide (H₂O₂,30%) were added. The samples were then kept at room temperature for 6 hours for homogenisation and slow digestion. The vessels were then closed, and the digestion process was carried out by applying a temperature programme of 170 °C for 18 minutes to the samples inside. After the digestion procedure, all digestion containers were left closed overnight to cool. The next day, the contents of the containers were transferred to vials, and the final volume was adjusted to 10 ml with ultrapure water. The colourless solutions obtained were read for further analysis. The emission wavelengths used in the qualitative and quantitative analysis of each metal are shown in Table 4. This shows how the light characteristics of its wavelength are used to determine the metal being measured. This is connected to a computer which displays the results in ppm (mg.kg^-1) (Bon et al., 2011).

Table 4
Elements trace of selected wavelength for metals quantified by ICP-OES.

Elements	Wavelength (nm)
Fe	238.20
Cu	327.39
Pb	220.35
Cr	267.71
Ni	231.6
Zn	206.2
Cd	228.8
Mn	279.8
Co	420

2.4 Hazard characterization of Pb, Cd, Ni, and Zn

The quantifiable hazard considered is the maximum tolerated human consumption limit per week and per kg body weight. The provisional tolerable weekly intake (PTWI) is 25 ug/kg bw/week, 2.5 ug/kg bw/week, 13 ug/kg bw/week (Schrenk et al., 2020), 175,000 ug/kg bw/week for lead, cadmium, nickel, and zinc, respectively (General Standard for Contaminants and Toxins in Food and Feed from Codex Alimentarius (CXS 193-1995)), where bw/week: body weight per week.

2.4.1 Estimating exposure

The estimated exposure is calculated using the following Formula 1 (Kouame et al., 2023):

$$AHM=C*Q/P$$ (1)

AHM: Average weekly intake of metallic elements (ug/kg bw/ week) C: Concentration of each metallic element in soumbara

Q: Quantity of soumbara consumed per week per person (Kané, 2019)

$Q=0.09865kg$

P: body weight of an adult equal to 70 kg

2.4.2. Determining the hazard quotient

The hazard quotient (Q) was obtained using the following Formula 2:

$$Q=AHM/DHTP$$ (2)

AHM: Average weekly intake of metallic elements

DHTP: Temporary Tolerable Weekly Intake

The result of the risk quotient allows conclusions to be drawn about the potential occurrence of effects, but also about their significance.

Q < 1 means that the exposed population is unlikely to develop the health effects under study.

Q > 1 means that toxic effects are likely to occur in the population.

2.5 Statistical processing

The analysis of variance (one-way ANOVA) was performed using XLSTAT 2014.1 software at the 5% significance level. In the event of a significant difference between the parameters studied, the means were ranked using the ANOVA method with post-hoc TUKEY test.

3 Results and discussion

3.1 Chemical hazards detected in soumbara sold on markets

The levels of trace elements (lead, cadmium, chromium, iron, manganese, copper, zinc, nickel, and cobalt) detected in soumbara sold on the markets varied from one market to another. The quantity varied from 0.012±0.011 mg/kg (in soumbara sold on the Adjamé market) to 0.015±0.014 mg/kg (in soumbara sold on the Cocody market) for lead. Cadmium levels varied from 0.015±0.012 mg/kg (in soumbara sold on the Port-Bouët market) to 0.019±0.012 mg/kg (in soumbara sold on the Adjamé market). Chromium levels ranged from 0.375±0.259 mg/kg (Port-Bouët market) to 0.075±0.034 mg/kg (in soumbara sold on the Treichville market). The results vary considerably from one market to another. The trace elements (lead, cadmium, and zinc) detected in the soumbara sold at the markets showed levels below the General Standard for Contaminants and Toxins in Food and Feed from Codex Alimentarius (CXS 193-1995). Nickel, copper, manganese, and iron levels were higher in soumbara sold on markets in Abidjan, Côte d'Ivoire. The difference in values is not significant at the 5% level. These results can be seen in Table 5.

Table 5
Quantity of trace elements detected in soumbara sold on the market.

Parameters	Markets
	Abobo	Treichville	Cocody	Port-Bouët	Adjamé	Limit threshold mg/kg (CXS 193-1995)
Pb (mg/kg)	0.013 ± 0.012a	0.013 ± 0.011a	0.015 ± 0.014a	0.014 ± 0.013a	0.012 ± 0.011a	0.1 - 0.3
Cd (mg/kg)	0.013 ± 0.011a	0.013 ± 0.012a	0.013 ± 0.012a	0.015 ± 0.012a	0.019 ± 0.012a	0.05 - 0.2
Cr (mg/kg)	0.125 ± 0.105a	0.075 ± 0.034a	0.158 ± 0.143a	0.375 ± 0.259a	0.140 ± 0.126a	0.2 - 0.5 ND
Fe (mg/kg)	3.462 ± 2.751a	3.487 ± 2.416a	3.472 ± 1.331a	3.512 ± 2.261a	3.537 ± 2.487a
Mn (mg/kg)	0.803 ± 0.631a	1.663 ± 1.447a	1.213 ± 1.111a	1.523 ± 1.349a	0.683 ± 0.461a
Cu (mg/kg)	0.672 ± 0.521a	0.618 ± 0.445a	0.614 ± 0.440a	0.619 ± 0.447a	0.616 ± 0.443a
Zn (mg/kg)	0.485 ± 0.248a	0.481 ± 0.254a	0.485 ± 0.248a	0.487 ± 0.246a	0.481 ± 0.253a
Ni (mg/kg)	0.401 ± 0.352a	0.935 ± 0.630a	0.610 ± 0.539a	0.635 ± 0.485a	0.450 ± 0.423a
Co (mg/kg)	0.020 ± 0.018a	0.025 ± 0.013a	0.043 ± 0.031a	0.080 ± 0.011a	0.040 ± 0.016a

In the same column, mean values followed by an alphabetical letter are not statistically different (p ≤ 0.05) (TUKEY treatment 5 4.018417 0.05), PP: Physicochemical parameters, Pb: Lead, Cd: Cadmium, Cr: Chromium, Fe: Iron, Mn: Manganese, Cu: Copper, Co: Cobalt, ND: Not determined

3.2 Trace elements contamination rates in soumbara sold in Abidjan markets

Of the 75 samples analyzed, 84% were contaminated with lead (Pb), 38% with cadmium (Cd), 40% with nickel (Ni), and 89% with zinc (Zn). Lead (Pb) and zinc (Zn) had the highest contamination rates in soumbara sold on the markets of Abidjan in Côte d'Ivoire. These results can be observed in Figure 2.

Figure 2
Percentage of soumbara sold in markets in Abidjan, Côte d'Ivoire, contaminated with trace elements.

3.3 Estimated intake of lead (Pb), cadmium (Cd), nickel (Ni), and zinc (Zn)

The study revealed that the weekly intake value for trace elements (AHM) is 0.0183 ug/kg bw/ w; 0.0183 ug/kg bw/ w; 0.6835 ug/kg bw/ w; and 0.5651 ug/kg bw/ w, respectively, for lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni) for soumbara sold at the Abobo market. As for the Treichville market, the weekly trace elements intake (AHM) for this food was 0.0183 ug/kg bw/ week; 0.0183 ug/kg bw/ week; 0.6778 ug/kg bw/ week; and 1.3176 ug/kg bw/ week, respectively, for lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni). For Cocody, it was 0.0211 ug/kg bw/ w; 0.0183 ug/kg bw/ week; 0.6835 ug/kg pc/p; and 0.8596 ug/kg bw/ week for lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni). As for Port-Bouët, it was 0.0197 ug/kg bw/ week; 0.0211 ug/kg bw/ week; 0.6863 ug/kg bw/ week; and 0.8948 ug/kg bw/ week for lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni), respectively. The weekly intake of heavy metals (AHM) for soumbara sold at the Adjamé market was 0.0169 ug/kg bw/ week; 0.0267 ug/kg bw/ week; 0.6778 ug/kg bw/ week; and 0.6341 ug/kg bw/ week for lead (Pb), cadmium (Cd), zinc (Zn), and nickel (Ni), respectively. However, the risk quotient (AHM/DHTP) was less than one (1) for all trace elements in soumbara sold at markets in Abidjan, Côte d'Ivoire. The consumption of soumbara does not pose any risk to consumer health. These results can be seen in Table 6.

Table 6
Estimated trace elements inputs in soumbara sold in Abidjan markets.

Markets	Heavy metals	AHM (ug/kg pc/p)	DHTP (ug/kg pc/p)	AHM/DHTP
Abobo	Pb	0.0183	25	0.000732
	Cd	0.0183	2.5	0.00732
	Zn	0.6835	175000	0.0000039
	Ni	0.5651	13	0.043469
Treichville	Pb	0.0183	25	0.000732
	Cd	0.0183	2.5	0.00732
	Zn	0.6778	175000	0.0000038
	Ni	1.3176	13	0.101353
Cocody	Pb	0.0211	25	0.000844
	Cd	0.0183	2.5	0.00732
	Zn	0.6835	175000	0.0000039
	Ni	0.8596	13	0.066123
Port-Bouët	Pb	0.0197	25	0.000788
	Cd	0.0211	2.5	0.00844
	Zn	0.6863	175000	0.0000039
	Ni	0.8948	13	0.068830
Adjamé	Pb	0.0169	25	0.000676
	Cd	0.0267	2.5	0.01068
	Zn	0.6778	175000	0.0000038
	Ni	0.6341	13	0.0487769

4 Discussion

This study aimed to assess the level of trace metal element (TME) contamination in soumbara sold on markets to evaluate the risks of consumer exposure. Trace metal elements (TME) are the third most important source of risk for food and feed after mycotoxins and microorganisms (Dauguet et al., 2011). These trace metals are bioaccumulative. This explains their toxicity. Mercury, lead, and cadmium are among the most dangerous (Bernard et al., 2012). They are among those attracting the attention of the international community (Guédénon, 2009). This study showed the presence of lead and cadmium in the soumbara sample analysed from the Cocody, Abobo, Treichville, Adjamé, and Port-Bouët markets. The average content of lead, cadmium, nickel, etc., remained below the standard (0.1 mg/kg) (General Standard for Contaminants and Toxins in Food and Feed from Codex Alimentarius (CXS 193-1995). The results of this study are similar to those (Kouamé, 2013; Alfred et al., 2019; Capo-Chichi et al., 2013), which showed the presence of cadmium and lead in cassava during research work. The presence of trace elements in food products requires the source of contamination to be identified (Bernard et al., 2012). For example, plants capture trace elements in the soil that have no known metabolic function (e.g., Cd, Hg, Pb, As, etc.) and are therefore considered "non-essential" (Mench & Denis, 2004). According to previous work carried out (Bouka et al., 2013) on Manihot esculenta cassava tubers in the phosphate extraction zone, the highest concentrations of Cd (0.67 mg.kg-1) and Pb (1.86 mg.kg-1) were observed at Asso Apégan. Compared with this work, our results for soumbara show lower concentrations of cadmium and lead. Soumbara is packaged during production in transparent plastic bags. According to a study (Diaby et al., 2022), the trace metal elements in plastic bags are sources of food contamination, and their migration increases with variations in temperature and time. Origins may also explain the disparities between concentrations, with imported soumbara coming from a variety of sources, ranging from the sub-region to the north of Côte d'Ivoire. Contamination of soumbara by trace elements could also be linked to the raw material, certain elements involved in the processing, and poor maintenance of production equipment. The ingestion of cadmium can lead to anaemia, digestive problems, and kidney damage, which in turn leads to bone disorders, unlike lead, which causes neurological disorders leading to encephalopathy and digestive problems in the body (Attar, 2020). Food is still the main source of exposure to trace elements for the general population who are not occupationally exposed, and the estimation of human exposure to metal pollutants is based on habits and concentrations of trace elements (Laurent et al., 2005) through the estimation of averages. However, the different types of food do not contribute to the same extent to this exposure.

The risk quotient (AHM/DHTP) for all the trace elements detected in soumbara was less than 1. However, frequent consumption of soumbara can increase the concentration of trace elements in the consumer's body. It is therefore important for people to be vigilant and to vary their diet to ensure better health.

5 Conclusion

This study aimed to assess the level of trace elements (TME) contamination in soumbara sold in markets to evaluate the risks of consumer exposure. It was found that soumbara sold in markets contained trace elements (TMEs) such as Cr, Ni, Co, Fe, Cu, Mn, Zn, Pb, and Cd. The average content of Iron, Manganese, Copper, Zinc, and Nickel exceeded the required standard (European Commission, 2023), while the other trace elements were present at trace levels. However, the Risk Quotient (AHM/DHTP) for all trace metal elements was less than 1. Consumption of soumbara sold in Abidjan markets does not present a health risk to consumers. Excessive consumption of this product could lead to illness. However, Producers must be trained in good production and hygiene practices to prevent product contamination.

Acknowledgements

The authors sincerely thank all the women soumbara producers who freely agreed to take part in this study.

Data Availability Statement

All data generated or analysed in this study are included in this published article.

• Cite as:
  Tanoh, K. R., Alfred, K. K., Bouatenin, K. M., Djué, Y. F., & Marina, K. (2026). Assessment of trace elements in soumbara seasoning from the Abidjan Market (Côte d'Ivoire). Brazilian Journal of Food Technology, 29, e2025112. https://doi.org/10.1590/1981-6723.1122025
• Funding:
  None.

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Edited by

• Section Editor:
  Silvia P. M. Germer.

Publication Dates

• Publication in this collection
  06 Mar 2026
• Date of issue
  2026

History

• Received
  09 Oct 2025
• Accepted
  19 Dec 2025