Investigation of the quality of drinking water was carried out aiming to evaluate health risks and toxicity arising from the content of heavy metals. Samples were analysed for the content of Pb, Cd, Cr, Ni, Cu, Fe, Zn, Al, and Mn. Water quality and health risk assessment were evaluated by comparing the obtained data with current National, EU, and WHO regulations as well as by using the hazard quotient and cancer risk (HQ and CR). Results showed that Al (in one sample) and Ni (in five samples) exceeded the maximum allowed limits. Based on the metal pollution index, MPI, it was concluded that none of the samples exhibited ‘very good quality’ (MPI > 0.3), whereas the overall quality of Glina bottled water was classified as toxic to humans and Trebeshina as moderately toxic. Selected samples exhibited no evident health risk to humans (HQ < 1). Among the toxic metals analysed, Ni, Cd, and Cr exhibited higher values of cancer risk index (CR > 10−4), whereas Pb exhibited the lowest value. Bottled water such as Qafeshtama, Lajthiza, Tepelena, Dukat, Spring, Living, and Aqua Pana as well as tap water collected in the area of Student's City in Tirana can be considered safe for human consumption.

  • Heavy metals can cause toxicity.

  • Severe health effects are closely related to long term use.

  • Toxicity and Cancer Risk indexes were used to evaluate water safety.

Throughout history, the quality of drinking water has been a factor in determining human welfare. Currently, waterborne toxic chemicals pose the greatest threat to the safety of water supplies in industrialized nations (U.S. Department of Health & Human Services 1999). There are many possible sources of chemical contaminants including wastes from industry, pesticide runoff from agricultural lands, general municipal wastes, etc. (Lippmann 1999). Inadequate management of chemical waste means that drinking water of hundreds of millions of people is dangerously contaminated or chemically polluted (WHO 2011). According to the World Health Organization (WHO), access to safe drinking water has been acknowledged as being essential to health, a basic human right, and a component of effective policy for health protection (WHO 2011).

Metals are considered heavy pollutants due to their toxicity, durability, and bioaccumulation in the environment. Among the heavy metals, As, Cd, Pb, Cr, Cu, Hg, and Ni are of major concern, mainly due to their presence at relatively high concentrations in drinking water and their effects on human health (USEPA 2012, 2014; Montuori et al. 2013).

Heavy metals include essential elements like iron and toxic metals like cadmium and mercury. Most of them have a tremendous affinity for sulphur and disrupt enzyme function by forming bonds with sulphur groups in enzymes. Protein carboxylic acid (–CO2H) and amino (–NH2) groups are also chemically bound by heavy metals. Cd, Cu, Pb, and Hg ions bind to cell membranes, hindering transport processes through the cell wall (Malachowski 1995).

According to the International Agency for Research on Cancer (IARC), inorganic As and Cd are classified as human carcinogens (IARC (International Agency for Research on Cancer) 2016). Arsenic is related to cancer risk and skin damage, whereas Cd is linked to kidney damage and cancer. Other effects such as heart diseases and blood cholesterol from Sb, anemia from Pb, kidney and liver damage from Hg, and gastrointestinal disorder from Cu are also reported (U.S. Department of Health & Human Services 1999; USEPA (U.S. Environmental Protection Agency 2014).

Sources of drinking water are mainly represented by fresh surface water (lakes, rivers, reservoirs) and groundwater aquifers (Manahan 2001; Cullaj et al. 2011). In the last decades, the use and demand of bottled water have increased, raising concerns regarding the quality of bottled water and the packaging material (mostly used polyethylene terephthalate (PET)) playing an important role as an adequate barrier against humidity, oxygen, and carbon dioxide (Chapa-Martínez et al. 2016).

Drinking water standards today are set by international organizations such as the WHO and US Environmental Protection Agency (USEPA), whereas each country sets national criteria for drinking water quality (USEPA 1977, 1992; WHO 2011). Thus, for example, Albania has a DCM (Decision of the Council of Ministers No. 379, dated 26.02.1998) ‘On the approval of the hygienic-health regulation for the control of the quality of drinking water’ that determines the recommended values for different parameters (including some metals) in drinking water (Decision of Council of Ministers 1998).

Commonly, human health risk evaluation is based on the comparison of the estimated concentrations with the recommended guidelines for a certain element, which in fact is not sufficient as it cannot provide adequate information on the hazard level as well as on the distinguishing of the most potential contaminant due to the long-term exposure (USEPA 1977, 1992, 1997). Human health risk of a certain hazardous substance, even if below the recommended value, is dependent on the type of element; the level of the element to which a person is exposed; the duration of exposure, and the quantity consumed (USEPA 1989, 1997, 2004, 2006, 2009). The most used guidelines on health risk assessments with regard to human exposure to different contaminants are based on the USEPA and WHO recommendations (USEPA 1989, 1997, 2004, 2006, 2009). Accordingly, risk assessment is defined as ‘the process of estimating the probability of occurrence of an event and the probable magnitude of adverse health effects on human exposure to environmental hazards over a specified period of time’. The health risk assessment of each potentially toxic metal is usually based on the quantification of the risk level and is expressed in terms of a carcinogenic or a non-carcinogenic health risk (Adamu et al. 2014; Wongsasuluk et al. 2016). The two principal toxicity risk factors evaluated are the slope factor (SF) for carcinogen risk characterization and the reference dose (RfD) for non-carcinogen risk characterization. The estimations of the magnitude, frequency, and duration of human exposure to each potentially toxic metal are reported as an average daily dose (ADDi), considering the fact that the main route of exposure to harmful substances by consuming drinking water is by ingestion.

The carcinogenic risk, CR is the possibility of an individual to develop any type of cancer during lifetime exposure to carcinogenic threats. According to USEPA (1989), the SF directly transforms the ADD of pollutants exposed over a lifetime to the continual risk of a cancer patient. Risk value, CR < 10−6 represents no carcinogenic risk to health, while a CR > 1 × 10−4 suggests a high risk of developing cancer. A risk value ranging from 1 × 10−6 to 1 × 10−4 signifies an acceptable risk to human health (USEPA 1989).

Albania's water resources amount to 41.7 × 109 m3 or 13.3 × 103 m3 per capita, of which about 65% are generated within Albania and the rest comes from neighboring countries. Consumption of drinking water is about 20–50 L per person per day (Cullaj et al. 2011). After 1990, due to population growth, the construction of the Bovilla Reservoir in 1998 was essential to address the demand for drinking water in the capital area (Cullaj et al. 2011). Bottled water is one of the few alternatives to drinking water that consumers can use. Nowadays, in Albania exist more than 14 springs which are used for bottled water production, among which eight are traded almost all over Albania, while the rest have mainly local use. The increasing use of industrialized water worldwide is associated with a loss of confidence in water supply.

In December 2021, the WHO updated chemical background documents for asbestos, Mn, Ni, and Ag. A number of chemical background documents were also published in December 2020. According to the DGWQ list of chemicals to be controlled, published by the WHO, heavy metals are of main importance (WHO 2022). The main purpose of this study was the evaluation of health risks associated with oral exposure to selected heavy metals being present in different types of drinking waters that are consumed preferably by Albanian inhabitants.

Selection of water samples

Water samples were collected from different sources in Albania, including bottled, tap, and spring water (15, 2, and 3 samples, respectively). Bottled water was collected randomly in the markets of Albania, comprising of nationally produced and imported brands. Tap water was collected in two different areas of Tirana city, aiming to differentiate water quality being supplied by different sources (respectively, Student's city is supplied by Selita natural spring water while the city center is supplied by the Buvilla reservoir). Water from natural springs is consumed untreated by many inhabitants of the three villages, Llogoraja, Tragjasi, and Dukati.

Samples collection and treatment were carried out in accordance with the standard methods ISO 5667, Part -5 and APHA/AWWA, 2017 (ISO 5667-5:2006 2006; APHA 2017). Samples were collected in polyethylene bottles, previously washed with nitric acid, HNO3 1: 1, and rinsed with deionized water. Initially, the water was allowed to flow for a few minutes and then collected in PET bottles with a volume of 1 L. Once the water samples arrived at the laboratory, spring water samples were filtered while all samples were acidified with 1 ml of nitric acid, HNO3 to pH <2. After acidification, the samples were stored in the refrigerator at 4 °C until the day of analysis.

Methodology of metals determination

Determination of the concentration of metals was performed by atomic absorption spectroscopy technique with graphite furnace atomization, AAS/GFAET. For this purpose, the Analytik Jena novAA400 instrument, equipped with a graphite furnace and autosampler type MP89 was used. For each element, instrumental conditions were first optimized, including HCL intensity, spectral bandwidth, wavelength, and graphite furnace program. The concentration of metals (Al, Zn, Cu, Fe, Cr, Mn, Pb, Cd, Ni) was calculated by the linear regression method.

Quality control of results

Quality control of results was performed through the analysis of replicates, blanks, and by analysis of a certified reference sample, CRM for the concentration of heavy metals in water, SPS-WW2 Batch 114. The experimental results for the CRM were within the limits of the confidence interval reported in the sample certificate. Statistical treatment of the results was carried out by using MINITAB19 and the Excel Analysis Tool Pack. Basic statistics such as mean and standard deviation were calculated by the descriptive statistics while the multivariate cluster analysis was used for the estimation of significant correlation between metals content in selected samples.

Metal pollution index

The pollution state of selected samples can be estimated by different indexes of pollution, of which the metal pollution index, MPI can be used as an indicator of the overall water quality related to heavy metals content and it is calculated by the following equation (Edet & Offiong 2002; Shehu et al. 2016):
where Ci is the measured concentration of each metal and MACi is the maximum admissible concentration of the ith metal. MPI values greater than 1 represent a threshold warning (Edet & Offiong 2002). Table 1 presents the MPI classification for water used for drinking and domestic purposes (Edet & Offiong 2002).
Table 1

Classification of water quality based on the MPI

MPICharacteristics class
<0.3 Very pure I 
0.3–1.0 Pure II 
1.0–2.0 Slightly affected III 
2.0–4.0 Moderately affected IV 
4.0–6.0 Seriously affected V 
>0.6 Seriously affected VI 
MPICharacteristics class
<0.3 Very pure I 
0.3–1.0 Pure II 
1.0–2.0 Slightly affected III 
2.0–4.0 Moderately affected IV 
4.0–6.0 Seriously affected V 
>0.6 Seriously affected VI 

Human health risk assessment

Average dose daily intake

There is a lack of information with regard to levels of toxic substances present in drinking waters in Albania, including heavy metals. The largest number of publications has been mainly focused on the evaluation of the environmental status of sources of water, while only few publications can be found with regard to human health risk assessment by both ingestion and/or dermal route (Shehu et al. 2021; Vallja et al. 2021). Bamuwuwamye et al. (2017) reported Pb to be a major contributor to non-cancer risks.

The two principal toxicity risk factors evaluated are the SF for carcinogen risk characterization and the reference dose (RfD) for non-carcinogen risk characterization (Li et al. 2013; Bamuwuwamye et al. 2017). The estimations of the magnitude, frequency, and duration of human exposure to each potentially toxic metal in the environment are reported as an ADD and it is calculated using the following equation:
Here, ADDi (mg/kg/day) is the average daily dose through ingestion of water, Ci is the concentration of the metal (mg/L), IR is the ingestion rate, EF represents exposure frequency, ED is exposure duration, BW indicates body weight, AT is the average time for non-carcinogens, ET represents exposure time, and CF is the conversion factor (Wongsasuluk et al. 2016). Values of all the above parameters are presented in Table 2.
Table 2

Standard values for calculating exposure assessment of trace metals in waters (USEPA 1989; Demir et al. 2015)

IndexNameValueUnit
Ci Concentration of metal in water – mg/L 
IR Water ingestion rate L/day 
Ef Exposure frequency 365 Days/year 
Ed Exposure duration 70 Years 
Bwt Average body weight 70 kg 
At Averaging time 25,550 Days 
Cf Unit conversion factor 1 × 10−3 L/cm3 
RfDi Cd = 0.0005; Cr = 1.5; Cu = 0.037; Ni = 0.020; Pb = 0.036; Zn = 0.3; Mn = 0.14; Fe = 0.7   
IndexNameValueUnit
Ci Concentration of metal in water – mg/L 
IR Water ingestion rate L/day 
Ef Exposure frequency 365 Days/year 
Ed Exposure duration 70 Years 
Bwt Average body weight 70 kg 
At Averaging time 25,550 Days 
Cf Unit conversion factor 1 × 10−3 L/cm3 
RfDi Cd = 0.0005; Cr = 1.5; Cu = 0.037; Ni = 0.020; Pb = 0.036; Zn = 0.3; Mn = 0.14; Fe = 0.7   

Hazard quotient

The human health risk of metals in the water samples was assessed as a non-carcinogenic hazard quotient, using the calculation as follows:

An HI < 1 signifies an acceptable level of risk, whereas HI > 1 represents an unacceptable risk of non-carcinogenic effects (APHA 2017).

Carcinogenic risk

The CR is the possibility of an individual to develop any type of cancer during lifetime exposure to carcinogenic threats. According to USEPA (1989), the SF directly transforms the ADD of pollutants exposed over a lifetime to the continual risk of a cancer patient. Risk value, CR < 10−6 represents no carcinogenic risk to health, whereas a value of CR > 1 × 10−4 suggests a high risk of developing cancer. A risk value ranging from 1 × 10−6 to 1 × 10−4 signifies an acceptable risk to human health, (USEPA 1989). The CR was calculated according to the formula:

Variation of metals concentration

Variation of metal concentrations in water samples is presented in Figures 1 and 2. Descriptive statistics are presented in Table 3. Water quality assessment with regard to heavy metals was based on the recommended values of the Albanian legislation, respectively Decision no. 379, dated: 25.05.2016 as well as on the WHO guidelines (WHO 2022, Guidelines for Drinking Water Quality).
Table 3

Descriptive statistics of metal concentrations

Al 20 41.7 10.3 46.2 7.5 14.4 26.3 50.8 209.8 
Zn 20 5.46 1.80 8.06 0.04 0.75 1.57 8.97 24.71 
Fe 20 7.41 1.76 7.87 0.00 0.10 4.10 16.58 21.50 
Cu 20 8.69 1.29 5.75 0.90 4.38 7.69 12.95 20.38 
Cr 20 1.75 0.21 0.93 0.47 1.18 1.62 2.39 4.53 
Mn 20 0.42 0.13 0.60 0.00 0.07 0.15 0.50 2.00 
Ni 20 18.07 4.62 20.66 1.55 6.44 9.63 22.03 89.87 
Pb 20 2.13 0.56 2.50 0.09 0.97 1.71 2.15 12.11 
Cd 20 0.076 0.006 0.026 0.05 0.06 0.065 0.10 0.13 
Al 20 41.7 10.3 46.2 7.5 14.4 26.3 50.8 209.8 
Zn 20 5.46 1.80 8.06 0.04 0.75 1.57 8.97 24.71 
Fe 20 7.41 1.76 7.87 0.00 0.10 4.10 16.58 21.50 
Cu 20 8.69 1.29 5.75 0.90 4.38 7.69 12.95 20.38 
Cr 20 1.75 0.21 0.93 0.47 1.18 1.62 2.39 4.53 
Mn 20 0.42 0.13 0.60 0.00 0.07 0.15 0.50 2.00 
Ni 20 18.07 4.62 20.66 1.55 6.44 9.63 22.03 89.87 
Pb 20 2.13 0.56 2.50 0.09 0.97 1.71 2.15 12.11 
Cd 20 0.076 0.006 0.026 0.05 0.06 0.065 0.10 0.13 
Figure 1

Variation of metals in water samples.

Figure 1

Variation of metals in water samples.

Close modal
Figure 2

Confidence intervals of metals in selected samples.

Figure 2

Confidence intervals of metals in selected samples.

Close modal

The mean concentration of heavy metals in selected water samples followed the order: Al (41.7 μg/L) > Ni (18.1 μg/L) > Cu (8.7 μg/L) > Fe (7.41 μg/L) > Zn (5.5 μg/L) > Pb (2.1 μg/L) > Cr (1.8 μg/L) > Mn (0.42 μg/L) > Cd (0.076 μg/L).

Among the analyzed metals, Al exceeded the maximum value (200 μg/L) recommended by DCM 379 of the Albanian legislation as well as the maximum value recommended by the European Directive in a tap water sample collected in the area of Tirana city center (Council Directive [98/83/EC] of 3 November 1998; Decision of Council of Ministers 1998). Also, the content of Al exceeded the limit value of 100 μg/L set by the WHO (WHO 2011, 2022). The reason stands in the fact that this area of the city is supplied with water by the Bovilla reservoir where aluminum salts are used in drinking water treatment processes to enhance the removal of particulate, colloidal, and dissolved substances via coagulation (Cullaj et al. 2011).

The concentration of Ni in bottled water samples ‘Trebeshina’, ‘BI’, ‘Evian’ and ‘Frassasi’ exceeded the maximum allowed value (20 μg/L) recommended by the Albanian legislation while in bottled sparkling water ‘Glina’ the concentration of Ni has resulted in higher than the maximum allowed value 70 μg/L, recommended by WHO (Decission of Council of Ministers 1998; WHO 2011, 2022).

With the exception of Glina water, where the Pb concentration resulted in close to the maximum permitted value, 10 μg/L recommended by the WHO, concentration of Pb was not exceeded in selected samples (WHO 2011, 2022). Concentrations of Fe, Mn, Cr, Zn, Cu, and Cd in selected samples were below the maximum allowed values, based on the Albanian legislation as well as on the EU and WHO recommendations (Decision of Council of Ministers 1998; WHO 2011, 2022).

Pearson correlation and cluster analysis

Correlation coefficients and simple cluster analysis were used to evaluate existing similarities of elements within and between samples (Figure 3). It was concluded that samples exhibited a high percentage of similarity coefficients, more than 90% regarding metals concentration (Figure 4). Despite the above, samples being produced in Albania were classified in the same group, while imported water like Frassasi, Aqua Pana, and Evian correlated better with each other.
Figure 3

Cluster analysis of metals.

Figure 3

Cluster analysis of metals.

Close modal
Figure 4

Cluster analysis of samples.

Figure 4

Cluster analysis of samples.

Close modal

A high correlation was observed between Ni–Cu (0.71), Pb–Ni (0.94), Cr–Ni (0.88), Cd–Cu (0.75), Ni–Cu (0.71), Pb–Cr (0.88) (Table 4 and Figure 3). Accordingly, metals were classified into three main groups: first group – Cu, Pb, Ni, Cd, Cr; second group – Al, Zn, Fe; and third group – Mn. Considering the above classification it is evident that metals were grouped according to their origin, i.e. metals with natural origin (second group) and metals originating by anthropogenic activities (first and third groups) (Lippmann 1999).

Table 4

Correlation matrix of elements

AlZnFeCuCrMnNiPb
Zn 0.53        
Fe 0.16 0.36       
Cu 0.23 0.01 0.27      
Cr 0.17 −0.21 −0.17 0.58     
Mn 0.00 −0.01 −0.25 −0.22 −0.19    
Ni 0.18 −0.22 −0.16 0.71 0.88 −0.20   
Pb 0.16 −0.11 −0.15 0.65 0.82 −0.19 0.94  
Cd 0.17 −0.23 −0.10 0.75 0.55 −0.27 0.63 0.44 
AlZnFeCuCrMnNiPb
Zn 0.53        
Fe 0.16 0.36       
Cu 0.23 0.01 0.27      
Cr 0.17 −0.21 −0.17 0.58     
Mn 0.00 −0.01 −0.25 −0.22 −0.19    
Ni 0.18 −0.22 −0.16 0.71 0.88 −0.20   
Pb 0.16 −0.11 −0.15 0.65 0.82 −0.19 0.94  
Cd 0.17 −0.23 −0.10 0.75 0.55 −0.27 0.63 0.44 

Values in bold present positive correlation that exist between metals, mainly related to their origin in water.

Table 5

Calculation of ADDi × 10−6 (mg/kg/day)

SampleAlZnFeCuCrMnNiPbCd
Tap water – Student's city 690 510 600 370 25 2.6 140 26 2.3 
Tragjasi reservoir 1,400 720 370 220 49 22 390 66 1.7 
Llogaraja spring 1,100 320 110 140 34 320 52 1.5 
Tragjas spring 1,100 400 220 45 9.9 400 51 2.0 
Tap water – Tirana city 6,100 700 500 280 49 16 290 48 1.7 
Trebeshina (0.5 L) 2,700 57 87 380 72 2.9 1,100 91 3.8 
Trebeshina (1.5 L) 650 19 460 84 11 1,100 100 3.8 
Living (sparkle 0.5 L) 930 45 32 140 55 2.6 250 36 2.0 
BI (0.5 L) 2,400 41 130 440 72 11 1,200 84 3.5 
Lajthiza (0.5 L) 1,500 58 140 26 17 26 45 2.6 1.7 
Qafeshtama (0.5 L) 340 33 160 46 74 1,100 14 1.7 
Glina (sparkle 0.5 L) 1,600 21 100 590 130 3.2 26,000 350 2.9 
Dukat (0.5 L) 470 52 68 39 270 39 2.0 
Dukat (1.5 L) 240 24 120 21 2.0 230 51 1.5 
Tepelena (0.5 L) 400 46 490 110 35 220 25 1.7 
Tepelena (1.5 L) 240 16 140 34 190 19 1.7 
Spring (0.5 L) 720 29 12 150 44 190 39 1.5 
Evian 510 1.2 620 360 62 8.4 600 51 1.7 
Frassassi 220 2.0 460 260 51 5.5 650 51 2.3 
Aqua Pana 810 87 490 28 2.0 170 45 2.9 
SampleAlZnFeCuCrMnNiPbCd
Tap water – Student's city 690 510 600 370 25 2.6 140 26 2.3 
Tragjasi reservoir 1,400 720 370 220 49 22 390 66 1.7 
Llogaraja spring 1,100 320 110 140 34 320 52 1.5 
Tragjas spring 1,100 400 220 45 9.9 400 51 2.0 
Tap water – Tirana city 6,100 700 500 280 49 16 290 48 1.7 
Trebeshina (0.5 L) 2,700 57 87 380 72 2.9 1,100 91 3.8 
Trebeshina (1.5 L) 650 19 460 84 11 1,100 100 3.8 
Living (sparkle 0.5 L) 930 45 32 140 55 2.6 250 36 2.0 
BI (0.5 L) 2,400 41 130 440 72 11 1,200 84 3.5 
Lajthiza (0.5 L) 1,500 58 140 26 17 26 45 2.6 1.7 
Qafeshtama (0.5 L) 340 33 160 46 74 1,100 14 1.7 
Glina (sparkle 0.5 L) 1,600 21 100 590 130 3.2 26,000 350 2.9 
Dukat (0.5 L) 470 52 68 39 270 39 2.0 
Dukat (1.5 L) 240 24 120 21 2.0 230 51 1.5 
Tepelena (0.5 L) 400 46 490 110 35 220 25 1.7 
Tepelena (1.5 L) 240 16 140 34 190 19 1.7 
Spring (0.5 L) 720 29 12 150 44 190 39 1.5 
Evian 510 1.2 620 360 62 8.4 600 51 1.7 
Frassassi 220 2.0 460 260 51 5.5 650 51 2.3 
Aqua Pana 810 87 490 28 2.0 170 45 2.9 

Water quality assessment based on MPI values

MPI values revealed that none of the samples exhibited ‘very good’ quality, i.e. with a value of MPI <0.3 (Figure 5). Tap water collected at Student's City, bottled water ‘Living’, ‘Qafështama’, ‘Lajthiza’, ‘Spring’, ‘Tepelena’, ‘Dukat’ and ‘Aqua Panna’ exhibited ‘good quality’. Frassasi and Evian bottled water; tap water taken in the area of Tirana city center; and stream water collected in the village of Tragjas were classified as ‘slightly toxic’, MPI 1–2. ‘BI’ Water and Trebeshina water were classified as moderately toxic, with values MPI 2–4. The only sample which was classified as ‘toxic’ water with regard to metals content was Glina bottled water, MPI 4–6.
Figure 5

The MPI of selected samples.

Figure 5

The MPI of selected samples.

Close modal

Health risk assessment

ADD calculations and HQ assessment

The HQ was calculated as the ratio of ADD/RfD (Tables 5 and 6). The human health risk assessment showed HQ values that suggest an acceptable level of non-carcinogenic health risk. Values of HQ ranged between 1 × 10−6 and 1.3 × 10−1 and followed the order: Ni > Cd > Pb > Cu > Al > Fe > Zn > Mn. However, all calculated values have resulted to be lower than 1, which means that all samples in the study are characterized by a low level of health risk.

Table 6

Hazard quotient, HQ × 10−3

SampleAlZnFeCuCrMnNiPbCd
Tap water – Student's city 0.69 1.69 0.85 9.16 168 0.02 7.19 7.37 4.64 
Tragjasi reservoir 1.39 2.39 0.53 5.61 325 0.16 19.7 18.8 3.48 
 Llogaraja spring 1.14 1.06 0.16 3.39 228 16.2 14.8 2.9 
Tragjas spring 1.09 1.33 5.54 300 0.070 19.8 14.5 4.06 
Tap water – Tirana city 6.06 2.32 0.71 6.87 325 0.11 14.4 13.8 3.48 
Trebeshina (0.5 L) 2.72 0.19 0.12 9.46 0.05 0.02 55.1 25.9 7.54 
Trebeshina (1.5 L) 0.65 0.06 11.6 0.06 0.08 53.7 28.8 7.54 
Living (sparkle 0.5 L) 0.93 0.15 0.04 3.48 0.04 0.02 12.6 10.4 4.06 
BI (0.5 L) 2.49 0.14 0.18 11.0 0.05 0.08 61.1 23.9 6.96 
Lajthiza (0.5 L) 1.50 0.19 0.20 0.65 0.01 0.18 2.25 0.75 3.48 
Qafeshtama (0.5 L) 0.34 0.11 0.22 1.14 0.05 5.37 3.89 3.48 
Glina (sparkle 0.5 L) 1.63 0.07 0.15 14.8 0.09 0.02 130 111 5.8 
Dukat (0.5 L) 0.47 0.17 1.70 0.03 13.5 11.1 4.06 
Dukat (1.5 L) 0.23 0.08 3.1 0.01 0.01 11.7 14.6 2.9 
Tepelena (0.5 L) 0.40 0.16 0.70 2.66 0.02 11.0 7.04 3.48 
Tepelena (1.5 L) 0.24 0.05 3.41 0.02 9.45 5.38 3.48 
Spring (0.5 L) 0.72 0.10 0.02 3.63 0.03 9.29 9.86 2.9 
Evian 0.51 0.004 0.89 9.06 0.04 0.06 29.9 14.7 3.48 
Frassassi 0.22 0.007 0.66 6.6 0.03 0.04 32.6 14.7 4.64 
Aqua Pana 0.81 0.29 0.70 13.1 0.02 0.01 8.64 12.8 5.8 
SampleAlZnFeCuCrMnNiPbCd
Tap water – Student's city 0.69 1.69 0.85 9.16 168 0.02 7.19 7.37 4.64 
Tragjasi reservoir 1.39 2.39 0.53 5.61 325 0.16 19.7 18.8 3.48 
 Llogaraja spring 1.14 1.06 0.16 3.39 228 16.2 14.8 2.9 
Tragjas spring 1.09 1.33 5.54 300 0.070 19.8 14.5 4.06 
Tap water – Tirana city 6.06 2.32 0.71 6.87 325 0.11 14.4 13.8 3.48 
Trebeshina (0.5 L) 2.72 0.19 0.12 9.46 0.05 0.02 55.1 25.9 7.54 
Trebeshina (1.5 L) 0.65 0.06 11.6 0.06 0.08 53.7 28.8 7.54 
Living (sparkle 0.5 L) 0.93 0.15 0.04 3.48 0.04 0.02 12.6 10.4 4.06 
BI (0.5 L) 2.49 0.14 0.18 11.0 0.05 0.08 61.1 23.9 6.96 
Lajthiza (0.5 L) 1.50 0.19 0.20 0.65 0.01 0.18 2.25 0.75 3.48 
Qafeshtama (0.5 L) 0.34 0.11 0.22 1.14 0.05 5.37 3.89 3.48 
Glina (sparkle 0.5 L) 1.63 0.07 0.15 14.8 0.09 0.02 130 111 5.8 
Dukat (0.5 L) 0.47 0.17 1.70 0.03 13.5 11.1 4.06 
Dukat (1.5 L) 0.23 0.08 3.1 0.01 0.01 11.7 14.6 2.9 
Tepelena (0.5 L) 0.40 0.16 0.70 2.66 0.02 11.0 7.04 3.48 
Tepelena (1.5 L) 0.24 0.05 3.41 0.02 9.45 5.38 3.48 
Spring (0.5 L) 0.72 0.10 0.02 3.63 0.03 9.29 9.86 2.9 
Evian 0.51 0.004 0.89 9.06 0.04 0.06 29.9 14.7 3.48 
Frassassi 0.22 0.007 0.66 6.6 0.03 0.04 32.6 14.7 4.64 
Aqua Pana 0.81 0.29 0.70 13.1 0.02 0.01 8.64 12.8 5.8 

CR evaluation

The risk of cancer is considered the possibility of an individual to develop a type of this disease during their lifetime as a result of exposure to a certain contaminant. In the present study, CR was assessed only for elements which are considered toxic for humans, respectively, Cr, Pb, Cd, and Ni. Results are presented in Table 7.

Table 7

CR values

SampleCrPbCdNi
Tap water – Student's city 0.005 8.59 × 10−5 0.006 0.007 
Tragjasi reservoir 0.010 0.0002 0.004 0.020 
Llogaraja spring 0.007 0.0002 0.003 0.016 
Tragjas spring 0.009 0.0002 0.005 0.020 
Tap water – Tirana city 0.010 0.0002 0.004 0.015 
Trebeshina (0.5 L) 0.014 0.0003 0.009 0.006 
Trebeshina (1.5 L) 0.017 0.0003 0.009 0.006 
Living (sparkle 0.5 L) 0.011 0.0001 0.005 0.013 
BI (0.5 L) 0.014 0.0003 0.008 0.006 
Lajthiza (0.5 L) 0.003 8.8 × 10−6 0.004 0.023 
Qafeshtama (0.5 L) 0.015 4.6 × 10−5 0.004 0.006 
Glina (sparkle 0.5 L) 0.026 0.0012 0.007 0.013 
Dukat (0.5 L) 0.008 0.0001 0.005 0.014 
Dukat (1.5 L) 0.004 0.0002 0.003 0.012 
Tepelena (0.5 L) 0.007 8.3 × 10−5 0.004 0.011 
Tepelena (1.5 L) 0.007 6.3 × 10−5 0.004 0.010 
Spring (0.5 L) 0.009 0.0001 0.003 0.010 
Evian 0.012 0.0002 0.004 0.030 
Frassassi 0.010 0.0002 0.006 0.030 
Aqua Pana 0.005 0.0001 0.007 0.009 
SampleCrPbCdNi
Tap water – Student's city 0.005 8.59 × 10−5 0.006 0.007 
Tragjasi reservoir 0.010 0.0002 0.004 0.020 
Llogaraja spring 0.007 0.0002 0.003 0.016 
Tragjas spring 0.009 0.0002 0.005 0.020 
Tap water – Tirana city 0.010 0.0002 0.004 0.015 
Trebeshina (0.5 L) 0.014 0.0003 0.009 0.006 
Trebeshina (1.5 L) 0.017 0.0003 0.009 0.006 
Living (sparkle 0.5 L) 0.011 0.0001 0.005 0.013 
BI (0.5 L) 0.014 0.0003 0.008 0.006 
Lajthiza (0.5 L) 0.003 8.8 × 10−6 0.004 0.023 
Qafeshtama (0.5 L) 0.015 4.6 × 10−5 0.004 0.006 
Glina (sparkle 0.5 L) 0.026 0.0012 0.007 0.013 
Dukat (0.5 L) 0.008 0.0001 0.005 0.014 
Dukat (1.5 L) 0.004 0.0002 0.003 0.012 
Tepelena (0.5 L) 0.007 8.3 × 10−5 0.004 0.011 
Tepelena (1.5 L) 0.007 6.3 × 10−5 0.004 0.010 
Spring (0.5 L) 0.009 0.0001 0.003 0.010 
Evian 0.012 0.0002 0.004 0.030 
Frassassi 0.010 0.0002 0.006 0.030 
Aqua Pana 0.005 0.0001 0.007 0.009 

CR = ADD × SF.

Bold values present no tendency to develop a cancer risk.

Values of CR followed the order: Ni > Cr > Cd > Pb. CR values of Ni varied from 0.006 to 0.030 suggesting high cancer risk in all selected samples. CR values for Cr and Cd ranged between 0.003–0.026 and 0.003–0.009, respectively, also suggesting a high cancer risk, while with regard to Pb, only one sample has exhibited a low cancer risk; Lajthiza bottled water and three samples have exhibited moderate cancer risk (Tepelena and Qafeshtama bottled water as well as tap water sample collected at the area of Student's city which is known to be supplied by the Selita natural springs). Trebeshina water and BI water were characterized by higher values of this parameter due to Cd while Glina water was due to Cr content. Waters Evian and Frassasi were characterized by higher CR values due to Ni content.

In this study, the quality of drinking water and the evaluation of the human health risk from heavy metals were carried out. In total, 20 samples, including bottled, tap, and natural spring water were selected for this study.

Results revealed that the mean concentration of heavy metals followed the order: Al > Ni > Cu > Fe > Zn > Pb > Cr > Mn > Cd.

Among the analyzed metals, Al exceeded the maximum recommended value in the tap water sample collected in the area of Tirana city center. The concentration of Ni in bottled water samples ‘Trebeshina’, ‘BI’, ‘Evian’, and ‘Frassasi’ exceeded the maximum allowed value (20 μg/L) recommended by the Albanian legislation (Decission of Council of Ministers 1998) while in bottled sparkling water ‘Glina’ the concentration of Ni has resulted higher than the maximum allowed value 70 μg/L, recommended by WHO (WHO 2011, 2022).

With the exception of Glina water, where the Pb concentration resulted close to the maximum permitted value, 10 μg/L, concentration of Pb was not exceeded in selected samples. Concentrations of Fe, Mn, Cr, Zn, Cu, and Cd in selected samples were below the maximum allowed values, based on the Albanian legislation as well as on the EU and WHO recommendations. The presence of heavy metals (Ni, Cu, Zn, Cd, Sb, Pb) is due to the anomalies caused by the interactions between the water and the plumbing system, especially in the cases of Pb and Ni, which are particularly soluble in acid water (Dinelli et al. 2012).

With regard to MPI, it was concluded that none of the selected samples exhibited ‘very good’ quality. Tap water collected at Student's City area, bottled water such as ‘Living’, ‘Qafështama’, ‘Lajthiza’, ‘Spring’, ‘Tepelena’, ‘Dukat’ and ‘Aqua Panna’ exhibited ‘good quality’. Frassasi and Evian bottled water; tap water taken in the area of Tirana city center; and stream water collected in the village of Tragjas were classified as ‘slightly toxic’; ‘BI’ water and Trebeshina water were classified as moderately toxic; whereas Glina bottled water was classified ‘toxic’.

Based on cluster analysis results, metals were classified into three main groups: first group – Cu, Pb, Ni, Cd, Cr; second group – Al, Zn, Fe; and third group – Mn. Considering the above classification it is evident that metals were grouped according to their origin, i.e. metals with natural origin (second group) and metals originating by anthropogenic activities (first and third groups) (Lippmann 1999).

The human health risk assessment of metal content in drinking water, based on the HQ values, suggests an acceptable level of non-carcinogenic health risk. Values of HQ ranged between 1 × 10−6 and 1.3 × 10−1 and followed the order: Ni > Cd > Pb > Cu > Al > Fe > Zn > Mn.

Different studies from Pakistan and Turkey indicated that studied drinking water sources are safe for consumption, but also could present risk at As and Cu, due to plumbing and pipe corrosion, with HQ values ranging from 1.0 to 8.7 (Muhammad et al. 2011; Demir et al. 2015).

With regard to CR calculated values, it was concluded that selected samples exhibited high values of CR, suggesting a high cancer risk index, CR of Ni, Cr, Cd, Pb > 10−4. Only one sample has exhibited a low cancer risk (Lajthiza bottled water) and three samples have exhibited a moderate cancer risk (Tepelena and Qafeshtama bottled water as well as tap water sample collected at the area of Student's city) with regard to Pb.

The above conclusions have been achieved based on the findings of just one time investigation. It is important to emphasise the CR index values, CR depends on factors such as concentration of metal, a daily dose of water consumption and body weight. In this study, calculations were made by using the maximum daily dose (i.e. 2 L/day), while usually the dose is lower, leading to lower values of CR. According to the formula of CR calculation, we can suggest that water with a certain concentration of a toxic metal can affect more people having low body weight compared to those with high BW, in a lifetime term.

While this study was conducted on a relatively low number of samples, we advise that future studies should expand our approach to larger number of water samples. Further investigation on the sources of these contaminants should be carried out, including water pipes and containers. Even though water intended for human consumption are being analysed before starting the water extraction (usually monthly) during the exploitation of the water resource, we recommend the number of parameters should be extended by including analysis of heavy metals, while health risk assessment should be considered when national standard values are determined. The future tendencies will consist of the comparison between the bottled water and the drinking water in centralized systems.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

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