Cadmium exposure in population: alcoholic beverage consumption and health risk assessment

Abstract

Risk assessment of cadmium (Cd) for human health play a key role because of toxic effect. Researchers are undergoing constant development for modelling approaches to make a risk assessment. It was carried out a central composite design combining with response surface modeling to optimize and modeling of Cd²⁺ ions in this study. Also, this study was performed to provide information about possible risk associated with alcoholic beverage consumption. Some independent process parameters including contact time and pH were chosen for optimization. Under optimal parameters, 142.9 mg g⁻¹ was determined as Cd²⁺ ions removal effectiveness. Significance independent parameters and their interactions were checked using analysis of variance. These results were verified by correlation coefficients (R² = 0.9967) of the statistical prediction. Estimated daily intake (EDI) and target hazard quotients (THQ) were calculated, to assess health risk. The Cd²⁺ ions EDI values (µg/day/person) were less than the recommended dietary allowance values and also, its THQ value was less than 1, also. When the obtained results compared with the levels set by regulatory authorities, the studied alcoholic beverages consumption do not pose a toxicological risk.

Graphical abstract

Introduction

Heavy metals, the main components of environmental pollution and non-biodegradable in nature, are a serious threat for ecosystem. Humans are exposed to these dangerous metals from a variety of sources, including contaminated food and drink. Food chain contamination is the most critical source for human exposure and the entry of these hazardous pollutants into the human body (Eticha and Hymete 2014). Harmful elements generally enter the food chain via man-made pollution. These detrimental elements can lead to severel health damage including kidney failure even so lung and blood cancer, because of their potential damage to human body especially the skeletal system (Arora et al. 2008). Heavy metal toxicity is dependent on various factors including the heavy metal chemical state, age, gender, excretion rate and bioavailability (Ismail et al. 2015). Cadmium (Cd) belongs to heavy metals and is classified as highly toxic element that are harmful for living beings even at very low concentrations (Záhorcová et al. 2016). Since Cd²⁺ ions are able to cross the placental barrier, it has been classified as a category 1 human carcinogen by the International Agency for Research on Cancer (IARC) (Al-Saleh et al. 2011; IARC 2012). The Cd²⁺ ions accumulation in biologic systems particularly in kidneys and cause various disorders. For example, it has vital risk of cardiovascular disease and developmental effects in children also, documented adverse effects on central nervous system, brain, liver, lungs and kidneys (Iwegbue et al. 2014; Sarkar et al. 2016). The Cd²⁺ ions lead to change of several metal that could represent early events of Cd²⁺ ions nephrotoxicity levels in the renal cortical (Åkesson et al. 2014; Prozialeck et al. 2016). Decrease of calcium and phosphate levels causes the formation of kidney stones. Moreover, at a more advanced stage, Cd²⁺ ions lesions can cause both acidification and concentration of urine along with a decline in bone mineral density. Because of long half life of Cd²⁺ ions, it is emphasized that it is more appropriate to evaluate a monthly value instead of weekly basis (provisional tolerable weekly intake, PTWI) was considered more appropriate by the FAO/WHO Joint Expert Committee on Food Additives (JECFA) (ATSDR 2012; Akerstrom et al. 2013; Berglund et al. 2015). As Cd²⁺ ions have long half-life, JECFA withdrew the PTWI of 7 mg kg body weight (bw) and decided to express the tolerable intake as a monthly value as a provisional tolerable monthly intake (PTMI), which was established as 25 mg kg⁻¹ bw (Muñoz et al. 2017). Furthermore, JECFA committee recommended PTWI of Cd²⁺ ions as 7 µg Cd/kg bw, for evaluating the health risk of this estimated dietary exposure (Muñoz et al. 2005). The Cd²⁺ ions concentration in urine are considered a valid biomarker of lifetime (kidney/body) accumulation from overall Cd²⁺ ions exposure and for identifying Cd-induced health effects. Because approximately 50% of Cd²⁺ ions accumulation in the body accumulates in the kidney, thus, as Cd²⁺ ions concentration calculated from the subject's urinary, exposure can be estimated from the load of Cd²⁺ ions in the renal cortex (Akerstrom et al. 2013; Berglund et al. 2015). The Cd²⁺ ions tolerable weekly intake (TWI) was stated as 2.5 μg kg bw⁻¹ by the European Food Safety Authority (Jean et al. 2018). Although several studies revealed that the Cd²⁺ ions content in alcoholic beverages is quite low, Cd²⁺ ions intake can be reached the maximum acceptable concentrations via diet (Pizzol et al. 2011). Alcoholic beverages particularly beer and wine are the most consumed drinks in Turkey, yet no data exist on the Cd²⁺ ions content of these beverages. This study focused on optimize experimental conditions to detect Cd²⁺ ions removal efficiency from alcoholic beverages using clay and its health risk assessment via consumption of these alcoholic beverages. To minimise processing costs, investigations have focused on the use of inexpensive and eco-friendly materials as adsorbents and also using a statistical approach for reducing number of experimental. Since the excessive time spent and extra chemical consumption for each variable, traditional methods have not been preferred. To optimize various process conditions, a RSM based on CCD approach was chosen and it was carried out to understand which experimental conditions, besides their interactions, play a vital role in Cd²⁺ ions removal from studied alcoholic beverages. This study mainly focused on two objectives. The first aim is to validate the validity of the used and proposed model by ANOVA, and the second aim is to optimize the selected variables using an experimental design to be able to assess Cd²⁺ ions exposure and risk for human health.

Materials and methods

Instrumentation and chemicals

In this study, a electrothermal atomic absorption spectrophotometer (ETAAS; AAnalyst^™ 800, PerkinElmer, Inc., Shelton, CT, USA)) was utilized. Because it has some advantages including practicability, sensitivity, precision, and accuracy. Batch adsorption experiments were carried out using a digital Jenco 6173 pH meter for solutions pH values and a JSR JSOS-500 model orbital shaker for shake of solutions. Hydrochloric acid, nitric acid, sodium hydroxide and cadmium standart in 5% nitric acid solution were obtained from Merck Company (Darmstadt, Germany) and all used chemicals were of analytical grade.

Acidified (with 0.5 M HNO₃) ultrapure water was used for Cd(II) stock (100 µg L⁻¹) solution preparation by dissolving an accurate quantity. Lower Cd²⁺ ions solution concentrations from stock solution were prepared by dilution for drawing calibration curve.

Adsorbent preparation procedure

Adsorbent material was treated with various solutions including sodium hydroxide, hydrochloric acid and ethanol follow Fig. 1 steps. Acid activated final product that impurity removed was kept in dry and clean containers for further use.

Fig. 1.

Acid activated clay process

Central composite design for optimization

An empirical statistical technique was selected to designed and determine experimental conditions. Presented methodology is useful to construct a regression model and an experimental study model. Used methodology offers some advantages for determining the optimum process variables with statistical technique (Alam et al. 2007; Garg et al. 2008; Tan et al. 2008). Based on CCD a quadratic model was selected for this study. When performed statistical experimental design in an adsorption process, it provides some advantages such as experimentation time and cost can be reduced (Singh et al. 2011). A statistical design called CCD has widely been used both to carried out experimental work with a minimum number of experiments and obtain a practical second-order model. In present study, the CCD approach was used both adsorption process variables optimization and to decide experiment numbers. The 2 k axial runs, 2 ^k factorial runs and central runs are the components that characterize the CCD. In present study, a total of 30 experiments (axial points; 8, factorial points; 16 and replicates; 6 at the center) were designed using CCD and they were given in Table 1. The number of experiments was calculated according to the Eq. 1.

$$N=2k+2^k+n_c$$ 1

where k and n_c represent the factors number and the center points number, respectively. The alpha (α), which depends on the number of rotational and factorial points, represents the distance from the center point of the axial point and can be calculated using below Eq. 2 (Dil et al. 2016):

$$\alpha =2^{\left(k/4\right)}$$ 2

Table 1.

Experimental factors and levels in the CCD

Factors	Levels			Star point α = 2
	Low( − 1)	Central (0)	High (+ 1)	− α	+ α
(X1) pH	3	5	7	1	9
(X2) Contact time (min)	15	20	25	10	35
(X3) Adsorbent dosage (mg)	10	15	20	5	25
4) Agitation speed (rpm)(X	100	150	200	50	250

Run	X1	X2	X3	X4	(mg g−1)
1	5	20	15	150	137.7
2	9	20	15	150	23.6
3	3	15	20	200	78.7
4	7	15	20	200	89.9
5	3	25	20	200	58.7
6	7	25	20	200	102.6
7	5	20	15	50	83.8
8	3	15	20	100	45.8
9	1	20	15	150	6.6
10	3	15	10	200	115.6
11	7	15	20	100	73.8
12	5	20	25	150	108.3
13	5	20	15	150	138.5
14	5	20	15	150	136.9
15	5	20	15	150	139.8
16	5	20	15	150	142.9
17	3	25	10	200	67.4
18	5	20	15	250	122.9
19	7	25	20	100	95.2
20	7	15	10	100	55.6
21	7	15	10	200	69.3
22	5	30	15	150	65.3
23	7	25	10	200	66.8
24	5	20	5	150	101.3
25	5	20	15	150	139.5
26	3	15	10	100	75.6
27	5	10	15	150	83.9
28	7	25	10	100	63.2
29	3	25	20	100	36.9
30	3	25	10	100	49.9

In present study, four factor that are influential on adsorption were selected for optimization and each factors coded as: − α, − 1, 0, + and + α. To design and optimize experimental conditions to remove Cd²⁺ ions using clay CCD model combining with RSM was used. As independent variables four critical factors affecting Cd²⁺ ions adsorption, namely solution pH (X₁), contact time (X₂), adsorbent amount (X₃), and agitation speed (X₄) were selected. Also, adsorbed Cd²⁺ ions amount (Y) was considered and a final equation that was derived from the regression analysis containing actual factors was presented. It was presented as below (Eq. 3):

$$\begin{array}{c}\mathit{Y}\left(\mathit{mgCd}/\mathit{gClay}\right)=-354.78+51.98X_1+20.53X_2+1.25X_3+1.79X_4+0.88X_1{X}_{2}1.22X_1{X}_3-0.04X_1{X}_4\\ +0.19X_2{X}_3-0.01X_2{X}_4+8.50E-0.04X_3{X}_4-7.88X_1^2-0.67X_2^2-0.36X_3^2-3.78X_4^2\\ \end{array}$$ 3

Table 1 representes independent variables’ levels of experimental range for adsorption of Cd²⁺ ions along with analysis of the experimental results. To propose a regression model Design Expert software program (Design Expert Version 10) was operated. The responses, during optimization process, can be simply concered with the selected factors by quadratic models. The proposed regression model is checked by means of tests including ANOVA as well as a lack of fit test.

Under predicted optimal conditions by using experiments that are identify by CCD, optimization results were verified. Predicted values of model that confirms CCD efficiency were strictly similar to results of corresponding experiments. According to obtanied data from CCD experimental design it can be said that CCD is the ideal approach to optimize the experimental variables when it used for Cd²⁺ ions removal from aqueous media by clay. It is good evidence that the difference between the experimental because predicted results can be ignored both proposed quadratic models’ efficiency and in predicting the optimum conditions. The optimal conditions were obtained to be 5.1 for pH of solution, 19.2 min for, 15.3 mg for adsorbent dosage, and 176 rpm for agitation speed respectively. Determination coefficient of R² characterizes the appropriate polynomial model. Because R² values, in the observed response values, provide a measure of how variability can be clarified by experimental variables. Fisher’s ‘F’-test and p-value perform these analyzes. Obtained experimental data and investigated four main effective factors were given in Table 2.

Table 2.

Analysis of variance (ANOVA) of the quadratic model

Source	Sum of squares	df	Mean square	F Value	p-value prob > F
Model	39686.16	14	2834.73	324.33	< 0.0001	Significant
X1-pH	618.13	1	618.13	70.72	< 0.0001
X2- Contact time	423.36	1	423.36	48.44	< 0.0001
X3- Ads dosage	43.20	1	43.20	4.94	0.0420
X4-Agitation speed	2227.23	1	2227.23	254.82	< 0.0001
X1 X2	1260.25	1	1260.25	144.19	< 0.0001
X1 X3	2376.56	1	2376.56	271.91	< 0.0001
X1 X4	318.62	1	318.62	36.45	< 0.0001
X2 X3	342.25	1	342.25	39.16	< 0.0001
X2 X4	171.61	1	171.61	19.63	0.0005
X3 X4	0.72	1	0.72	0.083	0.7777
X12	27237.60	1	27,237.60	3116.35	< 0.0001
X22	7592.40	1	7592.40	868.67	< 0.0001
X32	2265.12	1	2265.12	259.16	< 0.0001
X42	2449.44	1	2449.44	280.25	< 0.0001
Residual	131.10	15	8.74
Lack of fit	108.93	10	10.89	2.46	0.1665	Not significant
Pure error	22.17	5	4.43
Cor total	39817.27	29
R2	0.9967
R2Adj	0.9936
R2Pred	0.9834
Adeq precision	65.152

*p < 0.01 highly significant; 0.01 < p < 0.05 significant; p > 0.05 not significant

Sample collection, preparation and method application

Alcoholic beverage samples were collected randomly markets in Tunceli-Turkey. The alcohol content of the samples collected according to the criteria set by the European Commission (Union 2006) was range from 4.4 to 7.2%. Until analysis, obtained alcoholic beverages were stored in refrigerator. The presented method was used to determining level of Cd²⁺ ions concentrations in various real samples including beer and wine samples after the separation and enrichment of Cd²⁺ ions by solid phase extraction. The concentration of Cd²⁺ ions was tested for several alcoholic beverages. After concentrated Cd²⁺ ions using the adsorption technique, they were determined by the ETAAS. Instrumental operating conditions of AAnalyst 800 ETAAS were presented in Table 3. Limit of detection (LOD) and Limit of quantification (LOQ) values were calculated by using calibration graph as 0.012 µg L⁻¹ and 0.034 µg L⁻¹, respectively. The analytical method optimized and proposed using the quadratic programming combined with CCD was applied to a variety of alcoholic beverages. The acidification and solubilization of the samples was carried out by slightly changing the method used by Eticha and Hymete (2014). After acidification and degassing process, to prevent contamination, samples were placed into 250 mL glass beakers. Using the optimized experimental conditions, 200 mL of real samples were filtered and their pH were adjusted to 5. The samples were then treated according to the optimized conditions (agitated at 175 rpm with 15.29 mg of clay for 19.19 min). Adsorption and desorption procedure of Cd²⁺ ions concentrations from real samples were carried out based on previous study (Ince et al. 2021). Moreover, blanks were prepared likewise and supernatants were subsequently analyzed by using ETAAS to measurement concentration of Cd²⁺ ions. All the samples were analyzed in triplicate.

Table 3.

Instrumental operating conditions of AAnalyst 800 ETAAS

Step	Temp. (°C)	Ramp time (s)	Hold time (s)
Dry 1	110	1	30
Dry 2	130	15	30
Pyrolysis	500	10	20
Atomization	1500	0	5
Clean-out	2450	1	3
Wavelength (λ)		228.8 nm
EDL current		230 mA
Background correction		Zeeman-effect
Injection volume		20 μL
Slit width		0.7 nm

Risk assessment

Estimated daily intake (EDI)

In this survey, Cd²⁺ ions EDI, µg kg⁻¹ body weight day⁻¹, values were calculated and the results were presented in Table 4. While calculating the EDI values, the standardized person weight is 70 kg and the daily consumption of alcoholic beverages is 250 mL.

Table 4.

Daily exposure to Cd²⁺ ions levels by consuming alcoholic beverages and risk assesment for general population

Sample	Cd2+ ions amount (µg L−1)	EDI (µg kg−1)	THQ
Beer 1	0.072	0.00030	0.00030
Beer 2	0.066	0.00027	0.00028
Beer 3	0.072	0.00030	0.00030
Beer 4	0.057	0.00024	0.00024
Beer 5	0.079	0.00033	0.00033
Beer 6	0.130	0.00054	0.00054
Beer 7	0.140	0.00058	0.00058
Beer 8	0.160	0.00067	0.00067
Beer 9	0.122	0.00051	0.00051
Beer 10	0.110	0.00046	0.00046
Red wine 1	0.082	0.00034	0.00034
Red wine 2	0.099	0.00041	0.00041
Red wine 3	0.220	0.00092	0.00092
Red wine 4	0.125	0.00052	0.00052
Red wine 5	0.160	0.00067	0.00067
White wine 1	0.260	0.00108	0.00108
White wine 2	0.240	0.00120	0.00110
White wine 3	0.330	0.00138	0.00138
White wine 4	0.200	0.00083	0.00083
White wine 5	0.290	0.00121	0.00121

For evaluating the health risk of this estimated dietary exposure Cd²⁺ ions PTWI value was recommended by JECFA committee as 7 µg Cd²⁺ ions kg⁻¹ bw (JECFA 2010). The Cd EDI values were calculated using the Eq. 4:

$$\text{EDI}=\frac{\left(\text{Consumed alcoholic beverage amount}\left(\text{mL}\right)\times \text{Alcoholic beverage Cd concentration}\left(\text{mg}/\text{L}\right)\right)}{\text{Average body weight}\left(\text{kg}\right)}$$ 4

Target hazard quotient (THQ)

The THQ has been used for expressing non-carcinogenic risk effect, because it is used as marker. Morever, THQ values connects the elements concentrations in food with their toxicity, quality and quantity of food consumption and consumers’ body mass. The THQ is a very useful ratio as it provides more comprehensive information in the form of combinations of many complex parameters for assessing the potential health risk of elements in a variety of foods and beverages. To calculate and evaluate THQ values an equation was preferred by researchers (Ihugba et al. 2018) and mentioned equation was presented below.

$$\text{THQ}=\frac{\text{EDI}}{{\text{RfD}}_{\text{o}}}$$ 5

During the THQ values calculation, exposure duration as 365 days year⁻¹, exposure frequency as equivalent to the average lifetime about 70 years and alcoholic beverages consumption amount as g/person/day were represents. An estimate of the daily exposure to which a person can be exposed continuously throughout life, without significant risk of harmful effects, is expressed in Oral RfD_o (mg/kg/day). For Cd²⁺ ions, RfD_o is 0.001 (mg/kg bw/day) (Muñoz et al. 2017). The THQ value is used as a marker and according to the magnitude of this value, it is evaluated whether the agent in question has any serious effects on human health. For example, the US EPA mentioned that an index more than 1 generally indicates a potential for adverse human health effects. However, if value of THQ is less than 1, the exposed population are not experience any adverse health hazard. If the THQ value is equal to 1, the exposed population may experience non-carcinogenic health risks but its reported that as the value increases, the probability increases(Muñoz et al. 2017; Ihugba et al. 2018).

Results and discussion

Second-order polynomial model

Experimental design table (Table 1) and ANOVA table (Table 2) were presented for dexhibiting clay Cd²⁺ ions adsorption potential under optimum conditions. Based on ANOVA tablo data, selected model is very important based on model “F-value” because it measures significance of model. This model “F-value” was 324.33. While most of the model terms including X₁, X₂, X_3, X₄, X₁X₂, X₁X₃, X₁X₄, X₂X₃, X₂X₄, X₁², X₂², X₃², and X₄² are significant model terms, only one model term that is X₃X₄ is statistically insignificant. Because the "Probe > F" values presented in the ANOVA table are less than 0.05, the model terms are statistically significant, and if they are greater than 0.1, the model term is not statistically significant. The model correlation coefficient (R²) value, which is desired to be greater than 0.75 and considered sufficient (Kaplan Ince et al. 2018), was obtained as 0.9967 in this study. It can be said that 99.67% of the model-predicted values matched the experimentally. The “R²_Pred value” and “R²_Adj value” were obtained as 0.9834 and 0.9936, respectively, and the difference between them being smaller than 0.2 can be said to be in reasonable agreement. Whether a sufficient signal is obtained is measured by “Adeq Precision” and it is desirable that this value be greater than 4. Presented study “Adeq Precision” value was obtained as 65.15 and this value indicates an adequate signal. Another test parameter is the “Lack of Fit” (LOF) value, which measures the fit of the model. Because one of the most prominent features of a study is LOF greater than 0.05. If this value is greater than 0.05 (p > 0.05), it can be decided that the model is suitable. In this study, LOF value is obtained as 0.1665 and it implies the LOF is not significant relative to the pure error. As it is clearly seen from the data presented in the ANOVA table, it can be stated that the number of experiments performed is sufficient to determine the effects of the selected independent variables on Cd²⁺ ions adsorption and removal from alcoholic beverages. Obtained and presented in ANOVA table data revealed that proposed and used statistical model was adequate for predicting concentration of Cd²⁺ ions and was fitted to the second-order polynomial equation.

Response surface analysis

The regression equation is represented graphically by two-dimensional (2D) contour plots and three-dimensional (3D) response surface plots. Two factors effect on the response can be demonstrated these types of plots. Because of their usefulness, 2D and 3D graphs were made. Because, 2D and 3D graphs can help for determining response points including the minimum, middle and maximum points. Based on proposed model's measured responses and 3D response surface plots were formed and illustrated in Fig. 2. The Cd²⁺ ions adsorption efficiency of the influence of contact time–pH, adsorbent amount-pH, agitation speed-pH and agitation speed-contact time of 3D response surface was given in Fig. 2. According to 3D graphs, adsorbed Cd²⁺ ions amount increased when pH increase until 5 (p < 0.01), after which a decrease in Cd²⁺ ions adsorpion was observed. It is clear from the adsorbent contact time–pH binary interaction graph that adsorbed Cd²⁺ ions amount was increased when contact time was increased up to 20 min. Furthermore, the pH-agitation speed effect on the Cd²⁺ ions removal under other constant conditions, with an increase in agitation speed up to 180 rpm, it is clear that Cd²⁺ ions removal increased. As shown in Fig. 2, factors A (pH), B (contact time), C (adsorbent dosage) and D (initial Cd²⁺ ions concentration) were found to be very critical with respect to their centre points. Also, based on Cd²⁺ ions removal it is clear that experimental study values match predicted model values. Moreover, diagnostic plots of optimization using CCD for Cd adsorption process including interactions of normality -studentized residuals and studentized residuals besides run values of Cd²⁺ ions showed a good interaction. A perturbation plot (Fig. 3) was performed for comparing all factors that were effect on adsorption of Cd²⁺ ions. Moreover, analyze of factors variation and all the factors combined effect on a process was presented. All factors particularly pH indicates that removal of Cd²⁺ ions is highly affected by these variables. In addition to check the lambda (λ) value and enhance the significance of model, a Box-Cox plot was used for predicting any necessary transformation of the experimental value. Based on λ value (0.78) obtained from the plots, a power transformation that is proposed by system was made.

Fig. 2.

Effect of interaction between; a contact time and pH b adsorbent dosage and pH, c agitation speed and pH and d agitation speed and contact time on Cd²⁺ ions removal as 3D response surface plot

Fig. 3.

Diagnostic plots: Box-Cox plot and perturbation plot for Cd²⁺ ions removal, at the optimal conditions: solution pH 5.06 (A), contact time 19.19 min (B), adsorbent amount of 15.29 mg (C) and agitation speed 176 rpm (D)

Confirmation studies, under optimized conditions, were performed with the levels of parameters that suggested by the model gobal solutions (Table 5). The Cd²⁺ ions removal efficiency was calculated as 99%. There are a limited number of studies on the determination of Cd from alcoholic beverages (Donadini et al. 2008), examined nineteen beer brands purchased from the Italian markets and determined As, Cd²⁺ ions and Pb²⁺ ions levels using ICP-MS. They found concentrations of As, Cd and Pb ions as 10.82 ± 5.54 μg L⁻¹, 0.16 ± 0.15 μg L⁻¹ and 1.84 ± 3.24 μg L⁻¹, respectively. They reported that according to results beer samples does not pose health risk but may contribute heavy metals to the diet.

Table 5.

Possible global solutions

Number	pH	Contact time	Adsorbent amount	Agitataion speed	Cd2 + removal	Std err (Cd removal)	Desirability
1	5.1	19.2	15.30	177	142.2	1.172	0.995	Selected
2	5.1	19.2	15.34	176	142.2	1.173	0.995

Various beers produced in Ethiopia were surveyed to determine heavy metal content by (Eticha and Hymete 2014). After the digestion procedure samples were analysed by using AAS. They obtained metal concentrations as Cd²⁺ ions, 0.0014 mg L⁻¹; Cu²⁺ ions, 0.0368 mg L⁻¹; Mn²⁺ ions, 0.0954 mg L⁻¹; Pb²⁺ ions, 0.006 mg L⁻¹; Zn²⁺ ions, 1.5206 mg L⁻¹ in beer samples. According to the results, it was stated that the consumption of beers does not carry any health risk. Some elements including Cd²⁺ ions, Pb²⁺ ions and Ni²⁺ ions levels were measured by using AAS after digestion procedure by (Iwegbue et al. 2014) in various traditional alcoholic beverages consumed in southern Nigeria. They reported that these metals’ mean concentrations in traditional alcoholic beverages in the ranged of 0.02 mg L⁻¹–0.05 mg L⁻¹ for Cd²⁺ ions; 0.01 mg L⁻¹–0.19 mg L⁻¹ for Pb and nd-0.11 mg L⁻¹ for Ni. They stated that metals concentrations of in these alcoholic beverages were below statutory limits. (Muñoz et al. 2017), determined Cd²⁺ ions concentration in diet food groups in Valdiva. They analyzed alcoholic beverages besides various foods. They detected mean intake of alcoholic beverages 50.4 g/day and Cd²⁺ ions concentration 0.005 µg g⁻¹.

Method accuracy was checked by using NIST Standard Reference Material (SRM) 1643e Water (National Institute of Standards and Technology, USA). A recovery of standard addition study and standard reference material was obtained as 99%, also.

Alcohol consumption safety

As alcoholic beverages consumption, in humans, is a possible metal accumulation source, estimation of daily intakes of Cd²⁺ ions through alcoholic beverage consumption is very important. The EDI (mg/day/person) and THQ values are illustrated in Table 4.

The Cd²⁺ ions EDI values were calculated on the basis of consumption rate of daily alcoholic beverages and concentrations measured in alcoholic beverages. Based on the data obtained from this study and presented in Table 4, it can be stated that the EDI values of Cd²⁺ ions in alcoholic beverages are well below the corresponding tolerable daily intake values for 70 kg person values. Another assessment factor for risk assessment of food and food-related metal intake is calculated THQ values. Actually, estimated contaminant dose and reference dose ratio express via THQ values. It is concluded that there will be no significant risk if the values obtained are below the reference dose. Because an index value less than 1 is reported by the US EPA to be safe for human health (US EPA 2002). THQ values of alcoholic beverages consumption, in present study, are presented in Table 4. When considered consuming habits, it can be mentioned that the alcoholic beverages of daily intake has no risk for human health. Therefore, in terms of Cd²⁺ ions intake, alcoholic beverages consumption do not constitute a toxicological risk to human health.

Conclusion

It has been researched whether clay, which is an eco-friendly and economic material, can eliminate Cd²⁺ ions from the aqueous environment. The gains from this study are:

• After the CCD optimization process, at the optimum conditions, 5.06 for solution pH, 19.2 min for contact time, 15.3 mg for adsorbent dosage, 176 rpm for agitation speed, a 99% maximum Cd²⁺ ions removal was acquired.

• Once again at these optimum conditiond maximum Cd²⁺ ions adsorption capacity was calculated as 142.9 mg Cd²⁺ ions g⁻¹ clay.

• Sunstantial R² (0.9967) and R²_Adj (0.9936) values was attained from the ANOVA. As can be seen from the ANOVA table, 99.7% of the values predicted by the model match the experimental results about Cd²⁺ ions adsorption.

• The developed method was used to determine the Cd²⁺ ions levels in some real samples including beer and wine sample after the separation and enrichment of Cd²⁺ ions by solid phase extraction.

• The Cd²⁺ ions EDI values were calculated and evaluated for human health and the calculated values were found to be below the weekly tolerable values for a 70 kg person.

• Calculated Cd²⁺ ions THQ values are is far less than 1 in all studied alcoholic beverages, however if all other routes of entry of heavy metal is considered the potential health risks for human might actually be higher.

Abbreviations

ANOVA

Analysis of variance

CCD

Central composite design

EDI

Estimated daily intake

ETAAS

Electrothermal atomic absorption spectrophotometer

IARC

International agency for research on cancer

JECFA

Joint expert committee on food additives

LOF

Lack of fit

PTWI

Provisional tolerable weekly intake

RSM

Response surface modeling

SRM

Standard reference material

THQ

Target hazard quotient

TWI

Tolerable weekly intake

bw

Body weight

2D

Two-dimensional

3D

Three-dimensional

Authors’ contributions

OKI was responsible for conceptualization, resources, validation, writing and review and editing. MI was responsible for conceptualization, formal analysis, methodology, validation and writing. AO was responsible for resources and investigation.

Funding

The authors have not disclosed any funding.

Data availability

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

Declarations

Conflict of interests

The authors declare that they have no conflict of interests.