Assessment of Water Quality Index and the Probable Human Health Implications of Consuming Packaged Groundwater from Abeokuta and Sagamu, Southwestern Nigeria

Abstract

Background: Contamination of groundwater could result in serious and irreparable health problems for consumers. This study assessed the water quality and human health implications of metals in packaged groundwater from Abeokuta and Sagamu, southwestern Nigeria. Methods: One hundred and forty bags of the packaged groundwater were purchased and analyzed for physical and chemical parameters using standard procedures, while metals were determined using inductively coupled plasma optical emission spectrophotometry. Risk assessment of metals was estimated using hazard index (HI), hazard quotient (HQ), and cancer risk (CR). Water quality index (WQI) was also evaluated. Results: The observed physical and chemical parameters, except Mn and Fe, in the packaged groundwater samples were observed to be within the permissible limits of the World Health Organization. The WQI data indicated suitability for drinking purposes. The health risk data indicated high HQs > 1.0 for Ca (for adults and children at all the monitoring sites), Mn (children at all the sites, and adults at six sites), Mo (children at four sites, and adults at three sites), and Cu (children at three sites and adults at one site). Conclusion: The CRs of the packaged groundwater for Co and Ni at many sites revealed values > the acceptable limit of 1 × 10⁻⁴, indicating possible development of cancer by the consumers.

1. Introduction

Generally, water is an important nutritional requirement that promotes healthy living, maintains personal hygiene, prevents diseases, and improves quality of life [1,2,3,4]. A large percentage of people in developing countries depend mainly on groundwater from hand-dug wells or boreholes as a drinking source [5]. It is, therefore, necessary to safeguard groundwater resources for the preservation of lives. Groundwater can be contaminated with inorganic and organic substances by various anthropogenic activities such as industrialization, waste disposal, agriculture, and urbanization. Exposure to contaminated groundwater through ingestion and dermal contact may pose serious and irreversible health problems including non-carcinogenic and carcinogenic illnesses, such as inhibition of hemoglobin, psychosis, damage to the kidney and gastrointestinal tract (GIT), hemochromatosis, kidney and urinary tract illness, lung and breast cancer, teratogenic effects, neurological disorder (central nervous system (CNS) and peripheral nervous system (PNS)), poor intelligence quotient (IQ), increases in systolic and diastolic blood pressure, and poor development and low intelligent quotient in children [6,7,8,9].

Access to good-quality water is item number six on the list of Sustainable Development Goals (SDGs) [10]. It is, however, unfortunate that access to potable drinking water is still an issue of global concern, especially in developing countries, Nigeria included [11]. Despite the fractions of the national budget allotted to treat preventable waterborne diseases by the governments of developing nations, most citizens are still deprived of access to quality drinking water [12]. This might be related to problems such as social and technical costs and the political willpower to implement these systems [13]. Packaging of groundwater from boreholes into plastic materials (sachet water) for consumption is an alternative source of sustainable drinking water in most developing nations, where public drinking water is inaccessible and inadequate [14].

Packaged/sachet water is commercially manufactured, treated, and packaged into sealed polythene bags and distributed for sales and subsequent human consumption. It is a lucrative business in Nigeria, where it mostly serves the low-income socioeconomic class as a more affordable safe drinking water [3]. However, some packaged/sachet water manufacturers do not treat their water samples effectively before they are packaged for sale [15]. Unfortunately, most consumers tend to be more concerned about the appearance and taste of the packaged water than inherent potentially harmful loads of contaminants, such as physical (turbidity, suspended solids), chemical (organic (bisphenol A, phthalate esters, polycyclic aromatic hydrocarbons) and inorganic (Cd, Pb, Ni, Ba, Ti, Fe, Zn, Mn)), and microbial (total coliform, Escherichia coli) [16].

Heavy metal (HM) toxicity has become an important matter of public and scientific concern because of its evident deleterious health effects on biological systems [17]. While some HMs (e.g., Fe, Zn, Mn) are needed in trace concentrations for the proper functioning of the body system, some have no known physiological benefits (e.g., Cd, Ba, Pb, Ti, Tl, U, V). HMs are mobilized into water supply systems through anthropogenic and natural phenomena and, thus, gain entrance into the human body through ingestion (drinking) and dermal contact (bathing). They eventually become bio-available in the body system, where they contend and displace essential minerals (e.g., Ca, Cu, Mg, and Zn) and also restrict organs’ functions [18]. Several studies have reported the physicochemical and microbiological characteristics of sachet water [19,20,21,22,23], but very few have assessed its health risks [15], and few or none are on water quality index (WQI) and its relationship with health risk indices. The essence of the WQI is to determine the appropriateness of water for drinking purposes and the sustainable protection of public health [24]. A previous study of Taiwo et al. [6] revealed non-carcinogenic adverse effects of Al and Fe in groundwater from the mining areas of Ijeshaland, Osun State, Nigeria. The study also identified Cd as the major contributor to cancer risk in groundwater samples. The objectives of this study are to assess the water quality index and the probable human health impacts of metals in packaged/sachet groundwater from Abeokuta and Sagamu, Ogun State, Nigeria.

2. Materials and Methods

2.1. Study Area

Abeokuta, the largest city and capital of Ogun State, southwest Nigeria, is located at longitude 7°09′–7°39′ E and latitude 3°20′–3°54′ N. This ancient city lies on the east bank of the River Ogun, around a group of rocky outcroppings surrounded by wooded savanna. The metropolis of Abeokuta occupies four local government areas, viz: Abeokuta South (the largest fraction), Abeokuta North, and parts of Odeda and Obafemi Owode. The ancient city has a land cover of about 2320 km², which is expanding in all directions due to rapid population growth and urbanization [25].

Sagamu is an important city in Ogun State. It lies at longitude 3.63° E and latitude 6.83° N along the River Ibu and the Eruwuru stream, between Ibadan and Lagos. The city is known for the largest collection center for kolanut, thorn carvings, the carpet industry, and its Portland cement factory [26]. The map of the study area is shown in Figure 1.

2.2. Sample Collection and Analysis

One hundred and forty bags of packaged/sachet groundwater samples were purchased directly from seven different factories (i.e., 20 bags per factory) in Abeokuta and Sagamu, Ogun State, southwestern Nigeria. Samples were collected between March and June 2021. The packaged sachet water samples were subjected to analysis of their physical and chemical parameters, such as pH, total dissolved solids (TDS), electrical conductivity (EC), total suspended solids (TSS), alkalinity, hardness, chlorides, and metals (Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Zn).

pH, TDS and EC were analyzed electronically using a combined pH/EC/TDS probe (Hanna 98,130 Digit Multi-meter), which was standardized with standard buffer 4 and 7 solutions. The electrode was carefully rinsed with distilled water before measurement of the pH, EC, and TDS of the test samples. Total suspended solids (TSS) were determined gravimetrically by filtering 100 mL water samples through a pre-weighed filter paper and heating at 105 °C for 30 min (Uniscope SM 9023, Surgifriend Medicals, Okehampton Devon, UK). The oven-dried filter paper was allowed to cool in a desiccator for 15 min and then weighed in an analytical balance until a constant weight was achieved.

TSS was calculated by finding the difference between the initial weight and final weight of the filter paper and expressed as mg/L.

Alkalinity was assayed titrimetrically by measuring a 100 mL water sample into a 250 mL Erlenmeyer flask, followed by the introduction of 2 drops of phenolphthalein indicator and later a few drops of methyl orange indicator. The resulting solution was then titrated against 0.05 M H₂SO₄ until the color changed from orange to peach. Chloride was analyzed using Mohr’s method involving titration of a 100 mL water sample with 0.025M silver nitrate, while potassium chromate was used as the indicator [27]. Total hardness was assayed by titrating a 50 mL water sample with 0.05 M EDTA, while 1 mL ammonia buffer solution and 3 drops of Erichrome Black T (EBT) indicator were introduced.

The packaged water samples were analyzed for selected metals using inductively coupled plasma—optical emission spectrophotometry (ICP-OES). Prior to the determination of metals by the ICP-OES instrument, sachet water samples (100 mL) were digested with concentrated hydrochloric acid (10 mL) and heated for 30 min on a hot plate in a fume cupboard. Samples were allowed to cool and then filtered into clean (acid-washed, thoroughly rinsed, and oven-dried) digestion bottles. The digested extracts were transported to the CTX Ion Analytical Laboratory, Ikeja, Lagos, for metal analysis using the ICP-OES instrument (AGILENT 720).

Quality control procedures adopted included using reagents of analytical grade (Sigma-Aldrich Chemie, GmbH, Taufkirchen, Germany), running of blanks, and recovery experiments. Blank samples were analyzed to cancel out the background matrix effect of the extracting reagents. Furthermore, the percent recovery of the ICP-OES instrument was determined by spiking some samples with the standard solutions [28]. The recovery data ranged from 85 ± 4% (for Mn) to 101 ± 5% (for Ni).

2.3. Data Analysis

The packaged groundwater data were analyzed statistically with simple descriptive (mean and standard deviation) and inferential (regression analysis, Duncan multiple range test) assessments using the SPSS for Windows software package (version 22.0).

2.4. Water Quality Index (WQI)

The WQI model was calculated by using indices such as the water quality rating scale, relative weight, and WQI sub-index (Equations (1)–(4)) [29,30]. The WQI was estimated from packaged/sachet water parameters, namely pH, EC, TDS, total hardness, alkalinity, chloride, Ca, Cu, Fe, K, Mg, Mn, Na, and Zn (Table S1 in the Supplementary Information).

The water quality rating scale, Qi, was calculated as:

$$\mathrm{Qi}=\frac{\mathrm{Ci}}{\mathrm{Si}} \times 100$$

(1)

where Ci is the concentration of each (ith) parameter and Si is the standard value of each (ith) parameter.

Relative weight, Wi was estimated as:

$$\mathrm{Wi}=\frac{\mathrm{Wi}}{{\sum }_{\mathrm{i}=1}^{\mathrm{n}}\mathrm{Wi}}$$

(2)

where Wi is the weight of each (ith) parameter and n is the number of parameters.

The overall WQI was calculated as:

SIi = Wi × Qi

(3)

where SIi is the sub-index of the ith parameter, Qi is the water quality rating scale, and Wi is the relative weight.

WQI = ∑SIi

(4)

A WQI less than 50 denotes excellent water quality;a WQI range of 50.1 to 100 indicates good water quality; a WQI range of 100.1 to 200 designates poor water quality; a WQI range of 200.1 to 300 denotes very poor water quality; and a WQI greater than 300 specifies water unfit for consumption [31].

2.5. Health Risk Assessment

The human health risk of metals in the packaged groundwater samples was determined usingestimated daily intake (EDI), hazard quotient (HQ), hazard index (HI),andcancer risk (CR) using the USEPA models presented in Equations (5)–(8) [32,33,34].

$$\mathrm{EDI}=\frac{\mathrm{C} \times \mathrm{IR} \times \mathrm{EF} \times \mathrm{ED}}{\mathrm{BW} \times \mathrm{AT}}$$

(5)

where EDI is the estimated daily intake (µg/kg/day) of the exposed metals through consumption of the packaged/sachet groundwater, C is the concentration of metals (µg/L) observed in packaged/sachet water samples, IR is the ingestion/consumption rate of packaged/sachet water (2 L/day for adults, 1 L/day for children), ED is the exposure duration (30 years for carcinogenic effects for adults, and 6 years for children), EF is the exposure frequency (350 days/year) [23], AT is the average time, or life expectancy = 54.5 years [28,35] (AT = ED for non-carcinogenic effects, while AT = 54.5 × 365 days for carcinogenic effects for adults and 6 × 365 days for children [28]), and BW is body weight (60 kg for an adult and 15 kg for a child.

$$\mathrm{HI}={\sum }_{\mathrm{i}=1}^{\mathrm{n}}\mathrm{HQ}\mathrm{i}=1\dots \mathrm{n}$$

(6)

$$\mathrm{HQ}=\frac{\mathrm{EDI}}{\mathrm{RfD}}$$

(7)

where EDI is the estimated daily intake (µg/kg/day) of metals a person is exposed to through consumption of packaged/sachet water, RfD is the reference dose of metals (µg/kg/day) [26], and N is the number of metals observed in water samples.

HQ > 1 indicates non-carcinogenic adverse health effects, HQ < 1 denotes no adverse effects.

Cancer Risk = EDI × CSF

(8)

where EDI is the estimated daily intake (mg/kg/day) of the exposed metals through consumption of packaged/sachet water, and CSF is the cancer slope factor (1/mg/kg/day).

3. Results

3.1. Phyical and Chemical Characeteristics

The physical and chemical parameters of the packaged/sachet groundwater samples are presented in

Table 1. Physical and chemical parameters of packaged/sachet water.

	N = 140	N	Mean	SD	Minimum	Maximum	WHO [36]
pH	Iberekodo	20	7.40b	0.32	6.92	7.84	6.5–8.5
	Obada	20	7.70c	0.19	7.45	8.01
	Obantoko	20	7.65c	0.24	7.43	8.13
	Asero	20	7.46b	0.26	7.13	8.04
	Camp-Osiele	20	7.56bc	0.25	7.29	8.00
	Isolu	20	8.10d	0.51	7.32	9.53
	Makun-Sagamu	20	6.88a	0.12	6.65	7.12
EC	Iberekodo	20	144.80c	77.48	32.00	256.00	1000 *
(µS/cm)	Obada	20	39.15a	24.36	23.00	84.00
	Obantoko	20	23.85a	10.57	7.00	37.00
	Asero	20	37.10a	16.01	16.00	61.00
	Camp-Osiele	20	36.95a	3.39	26.00	42.00
	Isolu	20	61.80b	44.22	21.00	132.00
	Makun-Sagamu	20	31.40a	12.75	21.00	55.00
TDS	Iberekodo	20	72.60c	38.79	16.00	128	600
(mg/L)	Obada	20	19.55a	12.20	11.00	42.00
	Obantoko	20	11.85a	5.28	3.00	19.00
	Asero	20	18.60a	8.03	8.00	31.00
	Camp-Osiele	20	18.50a	1.79	13.00	21.00
	Isolu	20	31.60b	22.53	11.00	67.00
	Makun-Sagamu	20	15.70a	6.33	11.00	28.00
TSS	Iberekodo	20	0.01a	0.00	0.00	0.02
(mg/L)	Obada	20	0.12b	0.19	0.00	0.66
	Obantoko	20	0.00a	0.00	0.00	0.02
	Asero	19	0.00a	0.01	0.00	0.02
	Camp-Osiele	16	0.02a	0.01	0.00	0.03
	Isolu	20	0.00a	0.01	0.00	0.06
	Makun-Sagamu	20	0.05a	0.03	0.00	0.13
Hardness	Iberekodo	20	74.00ab	47.32	0.00	130.00	200.00
(mg/L)	Obada	20	5.00a	9.03	0.00	25.00
	Obantoko	20	18.30ab	29.42	0.00	135.00
	Asero	20	24.65ab	10.99	2.00	42.00
	Camp-Osiele	20	29.75ab	14.30	15.00	68.00
	Isolu	20	84.69b	266.51	0.70	1215.00
	Makun-Sagamu	20	11.25a	4.25	5.00	20.00
Alkalinity	Iberekodo	20	18.50c	6.51	5.00	30.00	120.00
(mg/L)	Obada	20	5.25a	2.91	2.50	10.00
	Obantoko	20	11.18b	3.73	5.50	17.50
	Asero	20	7.60a	3.90	4.50	20.00
	Camp-Osiele	20	6.50a	3.13	2.50	15.00
	Isolu	20	11.23b	10.25	0.00	40.00
	Makun-Sagamu	20	6.38a	3.08	1.00	12.50
Chloride	Iberekodo	20	53.50c	20.53	30.00	80.00	250.00
(mg/L)	Obada	20	10.38a	1.22	10.00	15.00
	Obantoko	20	10.33a	4.12	2.50	17.50
	Asero	20	16.00a	3.66	10.00	25.00
	Camp-Osiele	20	16.08a	2.84	12.50	24.00
	Isolu	20	30.69b	25.27	1.50	125.00
	Makun-Sagamu	20	8.77a	2.53	5.50	17.50

SD—standard deviation; dissimilar alphabets in superscript along same column are statistically different at p < 0.05, according to the Duncan multiple range test. * NDWQS [37].

. The pH of the packaged/sachet water samples varied from 6.88 ± 0.12 (Makun-Sagamu) to 8.10 ± 0.51 (Isolu). The pH values obtained in this study were within the permissible range of 6.5–8.5 for drinking water [36]. There were no significant variations in the levels of electrical conductivity (EC) observed in sachet water at different sampling sites, except at the Iberekodo site (Abeokuta). EC ranged from 31.40 ± 12.75 (Makun-Sagamu) to 144.80 ± 77.48 µS/cm (Iberekedo). The highest level of total dissolved solids (TDS, 72.60 ± 38.79 mg/L) was also observed in Iberekodo sachet water, while the lowest value (11.85 ± 5.28 mg/L) was found in Obantoko’s samples. TDS, hardness, alkalinity, and chlorides were also observed at their highest concentrations in Iberekodo sachet water. The levels of these parameters were within the acceptable limits in drinking water.

The data on major elements observed in packaged/sachet groundwater samples are shown in

Table 2. Major elements in packaged/sachet groundwater samples.

	N = 56	N	Mean	SD	Minimum	Maximum	WHO [38]
Ca	Iberekodo	8	12.88a	3.76	8.65	17.81	75
(mg/L)	Obada	8	9.47a	14.16	0.06	35.22
	Obantoko	8	86.54c	37.34	38.34	128.45
	Asero	8	36.31ab	6.66	27.44	42.36
	Camp-Osiele	8	24.12a	23.64	8.13	59.15
	Isolu	8	26.22a	19.23	8.43	52.83
	Makun-Sagamu	8	62.78bc	26.99	23.61	83.86
K	Iberekodo	8	4.68a	2.04	2.33	6.95	12
(mg/L)	Obada	8	4.54a	2.28	2.02	8.35
	Obantoko	8	3.05a	1.03	1.87	4.38
	Asero	8	20.36b	11.15	7.16	30.46
	Camp-Osiele	8	4.04a	3.62	1.8	9.42
	Isolu	8	9.26a	4.5	5.75	15.65
	Makun-Sagamu	8	5.58a	1.9	3.33	7.4
Mg	Iberekodo	8	0.30a	0.14	0.11	0.41	50
(mg/L)	Obada	8	3.12a	3.64	0.01	10.18
	Obantoko	8	4.93a	3.94	1.57	10.14
	Asero	8	4.22a	2.67	0.92	7.39
	Camp-Osiele	8	0.25a	0.11	0.12	0.36
	Isolu	8	12.33b	9.9	3.15	22.35
	Makun-Sagamu	8	7.43ab	6.07	2.83	15.97
Na	Iberekodo	8	7.53a	3.37	3.62	11.18	50
(mg/L)	Obada	8	36.05b	29.5	5.15	64
	Obantoko	8	15.80a	11.16	6.58	31.28
	Asero	8	34.91b	42.72	4.63	97.65
	Camp-Osiele	8	5.78a	2.54	2.58	8.02
	Isolu	8	15.46a	1.71	13.82	17.43
	Makun-Sagamu	8	9.27a	2.21	6.22	10.89

SD—standard deviation; dissimilar alphabets in superscripts along same column are statistically different at p < 0.05, according to the Duncan multiple range test.

. The levels of Ca were generally less than the permissible standard of 75 mg/L, except in Obantoko samples (86.54 ± 37.34 mg/L). The calcium content of sachet water purchased from this site was significantly higher than those collected from other sites, except Makun-Sagamu. K had its highest concentration (20.36 ± 11.15 mg/L) in Asero sachet water, above the WHO’s permissible level of 12 mg/L [38]. The highest significant level of Mg was established in sachet water purchased from Isolu. However, the Mg values in sachet water from all sites generally fell within the acceptable limit of 50 mg/L [38].

Although the highest significant level of Na (36.05 ± 29.5 mg/L) was observed in Obada sachet water, this was not statistically different from the Asero samples (34.91 ± 42.47 mg/L). Mg and Na had values lower than the permissible limits set by the WHO [38].

Table 3. Trace metals in packaged groundwater samples.

	N = 56	N	Mean	SD	Minimum	Maximum	WHO [36]
Co	Iberekodo	8	0.22a	0.02	0.20	0.23
(µg/L)	Obada	8	26.88ab	11.91	9.45	34.85
	Obantoko	8	4.62ab	5.44	0.89	10.86
	Asero	8	347.2b	231.5	13.87	548.5
	Camp-Osiele	8	0.89a	0.00	0.89	0.89
	Isolu	8	17.13ab	19.17	2.06	45.23
	Makun-Sagamu	8	20.25ab	27.94	0.49	40.00
Cu	Iberekodo	8	60.51a	72.75	18.23	169.5	2000
(µg/L)	Obada	8	238.7a	337.9	46.27	990.2
	Obantoko	8	76.77a	32.93	40.98	108.2
	Asero	8	1341b	1914	110.8	4194
	Camp-Osiele	8	83.20a	76.10	20.24	191
	Isolu	8	539.7ab	532.9	0.95	1030
	Makun-Sagamu	8	154.7a	163.5	1.00	363.4	300
Fe	Iberekodo	8	154.6a	133.2	8.00	420
(µg/L)	Obada	8	173.1a	214.2	18.00	896.8
	Obantoko	8	491.8a	559.1	19.00	1741
	Asero	8	178.9a	162.1	16.54	555
	Camp-Osiele	8	242.5a	317.5	23.00	901.2
	Isolu	8	172.6a	116.9	58.00	359
	Makun-Sagamu	8	561.4a	1090	12.00	3926
Mn	Iberekodo	8	7.62a	8.59	1.00	23.25	400
(µg/L)	Obada	8	1118ab	1719	26.50	4057
	Obantoko	8	340.3ab	312.2	16.00	825.3
	Asero	8	1380ab	2675	3.00	8272
	Camp-Osiele	8	46.45a	74.63	2.00	196.6
	Isolu	8	2393b	2455	9.00	4954
	Makun-Sagamu	8	1727ab	2218	4.00	4949
Mo	Iberekodo	8	1.37a	2.04	<0.1	4.00
(µg/L)	Obada	8	28.00a	0.00	28.00	28.00
	Obantoko	8	13.00ab	12.73	4.00	22.00
	Asero	8	<0.1a	0.00	<0.1	<0.1
	Camp-Osiele	8	<0.1a	0.00	<0.1	<0.1
	Isolu	8	21.00b	0.00	21.00	21.00
	Makun-Sagamu	8	20.00b	0.00	20.00	20.00
Ni	Iberekodo	8	<0.1a		<0.1	<0.1	70
(µg/L)	Obada	8	21.56b	1.01	20.14	22.86
	Obantoko	8	14.47b	8.09	3.31	22.65
	Asero	8	<0.1a		<0.1	<0.1
	Camp-Osiele	8	13.18b	0.00	13.18	13.18
	Isolu	8	5.97ab	0.00	5.97	5.97
	Makun-Sagamu	8	25.17b	2.86	23.30	29.40
Zn	Iberekodo	8	549b	653.5	5.56	1737	3000
(µg/L)	Obada	8	191.7ab	300.3	0.31	863.8
	Obantoko	8	428.1ab	435.4	33.04	1073
	Asero	8	298.7ab	222.9	147	779.7
	Camp-Osiele	8	83.77a	72.28	5.39	224.00
	Isolu	8	234.2ab	367.6	7.64	850
	Makun-Sagamu	8	429.7ab	281.4	53.00	734.4

SD—standard deviation; dissimilar alphabets in superscripts along same column are statistically different at p < 0.05, according to the Duncan multiple range test.

presents the levels of trace metals determined in packaged/sachet water samples. The highest levels of Co and Cu were observed in sachet water from Asero. Unfortunately, there is no permissible standard provided by the WHO for Co in drinking water. Therefore, Co may not be a threat in the packaged/sachet water samples in the study area, despite the high mean value of 347.2 ± 231.5 µg/L established in Asero samples. The highest Mn value was observed in Isolu sachet water samples.

The Cu levels in all the packaged/sachet water samples were within the permissible standard of the WHO [36]. Samples from Makun-Sagamu had the greatest concentrations of Fe (561.4 ± 1090 µg/L), Ni (25.17 ± 2.86 µg/L), and Zn (429.7 ±281.4 µg/L). Obada water samples had the highest values of Mo. However, Mo has no defined limit in drinking water. The Ni and Zn values for all the water samples were within the admissible limits of the WHO [36].

3.2. Water Quality Index

Figure 2 shows the overall water quality index (WQI) data for packaged groundwater from different sampling locations in the study area. The individual WQIs of samples were generally less than the acceptable limit of 100, indicating good quality (Table S1 in the Supplementary Material). However, the WQIs of sachet water from Iberekodo, Obada, Obantoko, and Camp-Osiele were less than 50, thereby indicating excellent quality. The highest WQI, 76, was documented in Isolu samples, to which Mn contributed at the highest level at 69%. In other sampling sites, such Obada, Makun-Sagamu, and Asero, Mn constituted 60%, 59% and 53% of the total WQI, respectively.

3.3. Human Health Risk Assessment

The estimated daily intake (EDI) values of metals in packaged groundwater are presented in Table S2 (in the Supplementary Material). Mn was the most-dosed metal in sachet water consumed by adults and children. Four out of the seven sampling sites showed a Mn EDI level greater than the adequate intake value of 1200 µg/day (equivalent to 80 µg/kg body weight) for children and 1800–2300 µg/day (equivalent to 30–38 µg/kg body weight) for adults [39].

Table 4. HQ and HI of metals in the packaged groundwater samples.

	HQ	Adults				Children
Metal (RfDs, µg/kg/day)		Mean	SD	Min.	Max.	Mean	SD	Min.	Max.
Ca	Iberekodo	412	120	277	569	823	240	553	1139
(0.001 *)	Obada	303	453	2	1126	605	905	4	2252
	Obantoko	2766	1194	1226	4106	5533	2387	2451	8212
	Asero	1161	213	877	1354	2321	426	1754	2708
	Camp-Osiele	771	756	260	1891	1542	1511	520	3782
	Isolu	838	615	269	1689	1676	1229	539	3378
	Makun-Sagamu	2007	863	755	2681	4014	1726	1509	5361
Co	Iberekodo	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
(60)	Obada	0.01	0.01	0.01	0.02	0.03	0.01	0.01	0.04
	Obantoko	0.002	0.003	0.000	0.01	0.005	0.01	0.001	0.01
	Asero	0.18	0.12	0.01	0.29	0.37	0.25	0.01	0.58
	Camp-Osiele	0.000	0.000	0.000	0.000	0.001	0.000	0.001	0.001
	Isolu	0.01	0.01	0.001	0.02	0.02	0.02	0.002	0.05
	Makun-Sagamu	0.01	0.01	0.000	0.02	0.02	0.03	0.001	0.04
	Mkun-Shgmu	0.19	0.11	0.08	0.29	0.38	0.22	0.16	0.58
Cu	Iberekodo	0.10	0.12	0.03	0.27	0.19	0.23	0.06	0.54
(20)	Obada	0.38	0.54	0.07	1.58	0.76	1.08	0.15	3.17
	Obantoko	0.12	0.05	0.07	0.17	0.25	0.11	0.13	0.35
	Asero	2.14	3.06	0.18	6.70	4.29	6.12	0.35	13.41
	Camp-Osiele	0.13	0.12	0.03	0.31	0.27	0.24	0.06	0.61
	Isolu	0.86	0.85	0.002	1.65	1.73	1.70	0.003	3.29
	Makun-Sagamu	0.25	0.26	0.002	0.58	0.49	0.52	0.003	1.16
Fe	Iberekodo	0.01	0.01	0.000	0.02	0.01	0.01	0.001	0.04
(700)	Obada	0.01	0.01	0.001	0.04	0.02	0.02	0.002	0.08
	Obantoko	0.02	0.03	0.001	0.08	0.04	0.05	0.002	0.16
	Asero	0.01	0.01	0.001	0.03	0.02	0.01	0.002	0.05
	Camp-Osiele	0.01	0.01	0.001	0.04	0.02	0.03	0.002	0.08
	Isolu	0.01	0.01	0.003	0.02	0.02	0.01	0.01	0.03
	Makun-Sagamu	0.03	0.05	0.001	0.18	0.05	0.10	0.001	0.36
Mg	Iberekodo	0.01	0.00	0.003	0.01	0.02	0.01	0.01	0.02
(1.1*)	Obada	0.09	0.11	0.000	0.30	0.18	0.21	0.001	0.59
	Obantoko	0.14	0.11	0.05	0.29	0.29	0.23	0.09	0.59
	Asero	0.12	0.08	0.03	0.21	0.25	0.16	0.05	0.43
	Camp-Osiele	0.01	0.00	0.00	0.01	0.01	0.01	0.01	0.02
	Isolu	0.36	0.29	0.09	0.65	0.72	0.58	0.18	1.30
	Makun-Sagamu	0.22	0.18	0.08	0.46	0.43	0.35	0.16	0.93
Mn	Iberekodo	0.49	0.55	0.06	1.49	0.97	1.10	0.13	2.97
(0.5)	Obada	71.48	109.90	1.69	259.38	142.95	219.80	3.39	518.76
	Obantoko	21.76	19.96	1.02	52.76	43.51	39.92	2.05	105.53
	Asero	88.23	171.02	0.19	528.86	176.46	342.04	0.38	1057.71
	Camp-Osiele	2.97	4.77	0.13	12.57	5.94	9.54	0.26	25.14
	Isolu	152.99	156.96	0.58	316.73	305.98	313.91	1.15	633.45
	Makun-Sagamu	110.41	141.80	0.26	316.41	220.83	283.61	0.51	632.81
Mo	Iberekodo	0.09	0.13	0.003	0.26	0.18	0.26	0.01	0.51
(0.5)	Obada	1.79	0.00	1.79	1.79	3.58	0.00	3.58	3.58
	Obantoko	0.83	0.81	0.26	1.41	1.66	1.63	0.51	2.81
	Asero	0.00	0.000	0.003	0.003	0.01	0.000	0.01	0.01
	Camp-Osiele	0.00	0.000	0.003	0.003	0.01	0.000	0.01	0.01
	Isolu	1.34	0.000	1.34	1.34	2.69	0.000	2.69	2.69
	Makun-Sagamu	1.28	0.000	1.28	1.28	2.56	0.000	2.56	2.56
Na	Iberekodo	0.07	0.03	0.03	0.11	0.14	0.06	0.07	0.21
(3.4*)	Obada	0.34	0.28	0.05	0.60	0.68	0.55	0.10	1.20
	Obantoko	0.15	0.10	0.06	0.29	0.30	0.21	0.12	0.59
	Asero	0.33	0.40	0.04	0.92	0.66	0.80	0.09	1.84
	Camp-Osiele	0.05	0.02	0.02	0.08	0.11	0.05	0.05	0.15
	Isolu	0.15	0.02	0.13	0.16	0.29	0.03	0.26	0.33
	Makun-Sagamu	0.09	0.02	0.06	0.10	0.17	0.04	0.12	0.20
Ni	Iberekodo	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
(20)	Obada	0.03	0.00	0.03	0.04	0.07	0.00	0.06	0.07
	Obantoko	0.02	0.01	0.01	0.04	0.05	0.03	0.01	0.07
	Asero	0.000	0.000	0.000	0.000	0.000	0.000	0.000	0.000
	Camp-Osiele	0.02	0.000	0.02	0.02	0.04	0.000	0.04	0.04
	Isolu	0.01	0.000	0.01	0.01	0.02	0.000	0.02	0.02
	Makun-Sagamu	0.04	0.005	0.04	0.05	0.08	0.01	0.07	0.09
Zn	Iberekodo	0.06	0.07	0.001	0.19	0.12	0.14	0.001	0.37
(300)	Obada	0.02	0.03	0.000	0.09	0.04	0.06	0.000	0.18
	Obantoko	0.05	0.05	0.004	0.11	0.09	0.09	0.01	0.23
	Asero	0.03	0.02	0.02	0.08	0.06	0.05	0.03	0.17
	Camp-Osiele	0.01	0.01	0.001	0.02	0.02	0.02	0.001	0.05
	Isolu	0.02	0.04	0.001	0.09	0.05	0.08	0.002	0.18
	Makun-Sagamu	0.05	0.03	0.01	0.08	0.09	0.06	0.011	0.16
HI	Iberekodo	413				825
	Obada	377				753
	Obantoko	2789				5579
	Asero	1252				2503
	Camp-Osiele	774				1548
	Isolu	994				1988
	Makun-Sagamu	2119				4239

HQ—hazard quotient, HI—hazard index, * mg/kg/day, SD—standard deviation, Min.—minimum, Max.– maximum, RfD—reference dose.

presents the hazard quotient (HQ) and hazard index (HI) values of metals in the packaged groundwater. Ca had the highest HQ values, greater than the acceptable limit of 1.0, in sachet water samples consumed by adults and children, thereby establishing non-carcinogenic adverse health effects. High HQs, greater than the acceptable limit of 1.0, were documented for Cu in the packaged groundwater consumed by adults (at one site) and children (at three sites).

Figure S1 (in the Supplementary Information) shows the contributions of metals to the non-carcinogenic adverse effects of sachet water. Ca was the highest contributor to the adverse health effects, with fractions ranging between 80% (Obada) and 100% (Iberekodo). Mn was the second-largest contributor to the non-carcinogenic effects, with values varying from 5% (Makun-Sagamu) to 19% (Obada).

The cancer risk (CR) data of Co and Ni in the packaged/sachet groundwater are shown in

Table 5. Cancer risk values of Co and Ni in the packaged groundwater.

			Adults				Children
Metals (CSF, 1/mg/kg/day)	CR	Mean	SD	Min.	Max.	Mean	SD	Min.	Max.
Co	Iberekodo	3.8 × 10−5	3.4 × 10−6	3.4 × 10−5	4.0 × 10−5	2.8 × 10−4	2.5 × 10−5	2.5 × 10−4	2.9 × 10−4
(9.8)	Obada	4.6 × 10−3	2.1 × 10−3	1.6 × 10−3	6.0 × 10−3	3.4 × 10−2	1.5 × 10−2	1.2 × 10−2	4.4 × 10−2
	Obantoko	8.0 × 10−4	9.4 × 10−4	1.5 × 10−4	1.9 × 10−3	5.8 × 10−3	6.8 × 10−3	1.1 × 10−3	1.4 × 10−2
	Asero	6.0 × 10−2	4.0 × 10−2	2.4 × 10−3	9.5 × 10−2	4.4 × 10−1	2.9 × 10−1	1.7 × 10−2	6.9 × 10−1
	Camp-Osiele	1.5 × 10−4	0.0	1.5 × 10−4	1.5 × 10−4	1.1 × 10−3	0.0	1.1 × 10−3	1.1 × 10−3
	Isolu	3.0 × 10−3	3.3 × 10−3	3.6 × 10−4	7.8 × 10−3	2.1 × 10−2	2.4 × 10−2	2.6 × 10−3	5.7 × 10−2
	Makun-Sagamu	3.5 × 10−3	4.8 × 10−3	8.4 × 10−5	6.9 × 10−3	2.5 × 10−2	3.5 × 10−2	6.1 × 10−4	5.0 × 10−2
Ni	Iberekodo	8.0 × 10−7	0.0	8.0 × 10−7	8.0 × 10−7	5.8 × 10−6	0.0	5.8 × 10−6	5.8 × 10−6
(0.91)	Obada	3.5 × 10−4	1.6 × 10−5	3.2 × 10−4	3.7 × 10−4	2.5 × 10−3	1.2 × 10−4	2.3 × 10−3	2.7 × 10−3
	Obantoko	2.3 × 10−4	1.3 × 10−4	5.3 × 10−5	3.6 × 10−4	1.7 × 10−3	9.4 × 10−4	3.9 × 10−4	2.6 × 10−3
	Asero	8.0 × 10−7	0.0	8.0 × 10−7	8.0 × 10−7	5.8 × 10−6	0.0	5.8 × 10−6	5.8 × 10−6
	Camp-Osiele	2.1 × 10−4	0.0	2.1 × 10−4	2.1 × 10−4	1.5 × 10−3	0.0	1.5 x 10−3	1.5 × 10−3
	Isolu	9.6 × 10−5	0.0	9.6 × 10−5	9.6 × 10−5	6.9 × 10−4	0.0	6.9 × 10−4	6.9 × 10−4
	Makun-Sagamu	4.0 × 10−4	4.6 × 10−5	3.7 × 10−4	4.7 × 10−4	2.9 × 10−3	3.3 × 10−4	2.7 × 10−3	3.4 × 10−3
	Iberekodo	3.9 × 10−5				2.9 × 10−4
∑CR	Obada	5.0 × 10−3				3.7 × 10−2
	Obantoko	1.0 × 10−3				7.5 × 10−3
	Asero	6.0 × 10−2				4.4 × 10−1
	Camp-Osiele	3.6 × 10−4				2.6 × 10−3
	Isolu	3.1 × 10−3				2.2 × 10−2
	Makun-Sagamu	3.9 × 10−3				2.8 × 10−2

CR—cancer risk, SD—standard deviation, Min.—minimum, Max.—maximum, RfD—reference dose.

. The CR values of Co were higher than the acceptable limit of 1.0 × 10⁻⁴ [32] at all the sampling sites, except in Iberekodo. Furthermore, the CRs of Ni at Obada, Obantoko, Camp-Osiele, and Makun-Sagamu were also higher than the permissible limit, establishing the probable development of cancer. The contributions of Co and Ni to the sum of cancer risk are shown in Figure S2 (in the Supplementary Material). Co formed the largest portion (42–100%) of the total cancer burden. Ni was the largest contributor (58%) to the total cancer risk at the Camp-Osiele sampling site.

3.4. Regression Model

Table 6. Regression of water quality index and the human health risk of packaged/sachet water samples.

	Regression Model	R	R2	Significance
WQI	33.94 +0.01 HI + 307.56 CR	0.387	0.149	0.723

WQI—water quality index; HI—hazard index; CR—cancer risk.

presents the regression model of WQI against hazard index and cancer risk. The model indicates a weak relationship between the water quality index and health risk indices.

4. Discussion

4.1. Phyical and Chemical Characeteristics

The sachet water samples from the Abeokuta metropolis were slightly alkaline, while those from Makun-Sagamu were slightly acidic in nature. Therefore, the pH of sachet water is comparable to the levels determined in groundwater samples from major cities in the southwestern part of Nigeria [40]. Although the EC values in water samples were lower than the permissible standard of 1000 µS/cm stipulated by the WHO [41], the level observed in Iberekodo packaged/sachet water was four times higher than those from other sampling sites. A past study by Shiaka et al. [23] observed a higher value of EC in sachet water from Zamfara, the northern part of Nigeria.

Total suspended solids (TSS) values observed in packaged/sachet water were usually very low, similar to those reported by Opafola et al. [22] in sachet water samples from a tertiary institution in Nigeria. This indicates possible good quality for these packaged groundwater samples, similar to the values reported by Ojekunle et al. [5] in groundwater from Sagamu. A previous study by Ndur et al. [19] observed lower concentrations of Ca, K, and Mg and higher Na levels in sachet water samples collected from Tarwa, Ghana.

This study showed Co levels generally higher than the range of less than 2 µg/L that is often observed in drinking water [42]. Similar to the present study, Atashi et al. [43] reported Co that varied between 172 and 204 µg/L in groundwater from Zahedan city in Iran. The average amount of Fe in the Obantoko and Makun-Sagamu samples was higher than the acceptable limit of 300 µg/L [36], similar to the past study by Naabil et al. [44] in sachet water from the Bolgatanga Municipality of Ghana. A high level of Fe in water is associated more with aesthetic quality (e.g., taste, smell, and colour)than health issues [36]. A previous study by Emenike et al. [15] reported similar high concentrations of Fe greater than the permissible standard of the WHO in packaged/sachet water collected from Ado Odo Ota, Ogun State, Nigeria.

Approximately 57% of the sampling sites had Mn contents greater than the permissible limit of 400 µg/L [36]. In groundwater, a Mn concentration of up to 1300 µg/L is attainable due to the reducing reaction in natural conditions, while the level can reach 9600 µg/L in an acidic medium [36]. High levels of Mn in water can cause brain damage in infants and young adults [45]. The WHO [46] documents that the level of Mo in drinking water rarely exceeds 10 µg/L. This concentration was exceeded in samples from Obada, Obantoko, Isolu, and Makun-Sagamu.

4.2. Water Quality Index

The WQI data at all the sampling sites indicates good quality with values generally less than 100.However, it should be noted that the dominance of Mn in the sachet water could pose health threats to consumers.

4.3. Human Health Risk Assessment

4.3.1. Hazard Quotient and Hazard Index

All the monitoring sites revealed HQs greater than 1.0 for Ca in packaged water samples ingested by adults and children. Mn also exhibited HQ > 1.0 in samples taken for children at all the monitoring sites; however, for adults, only one site has HQ < 1.0. This also established the adverse health effects of Mn through the consumption of the packaged groundwater samples. Mn is an essential trace metal providing assistance to many enzymes for their catalytic and regulatory functions. It is also needed for healthy cartilage and bone and plays a key role in wound healing [38]. High contents of Mn may result in a neurological disorder known as ‘manganism’; a condition characterized by body weakness, lethargy, slow and clumsy gait, speech disturbance, a masklike face, tremors, and psychological disturbances [36].

An adverse health effect was also estimated for Mo, with HQs greater than 1.0 in sachet water samples taken for adults (at three sites) and children (at four sites). Mo is a mineral the body requires to process proteins and genetic material such as DNA and for the metabolism of xenobiotics in the body [47]. Specifically, Mo is involved in the activation of enzymes that assist in breaking down deleterious sulfites and prevent toxins from building up in the body [48]. Furthermore, the reaction of Mo with sulfur can assist in reducing the amount of copper in the body—a possible future treatment for some chronic diseases [48]. Toxicity due to Mo rarely occurs in humans; however, high concentrations have been linked to kidney failure, diarrhea, reduced growth, and infertility in animals [48].

Ca is a major essential element required for the growth and strength of bones, maintenance of proper hormone levels, and the optimal function of nerves [49]. However, high levels of Ca can cause a condition known as hypercalcemia, which is characterized by headache, fatigue, kidney stones, excessive urination and thirst, nausea, and abdominal pain [50].Hypercalcemia may result from high Ca absorption due to lung diseases, cancer of the lung, and hyperthyroidism [49].

Correspondingly, the past work of Emenike et al. [15] reported HQs > 1.0 for Cu in selected brands of sachet water samples from Ado Odo Ota, Ogun State, Nigeria. The hazard index (HI) values of metals in sachet water were generally greater than the acceptable limit of 1.0, indicating unsafe consumption. Mgbenu and Egbueri [31] reported a high HQ value for Ni, greater than the permissible limit, for children that consumed water from Umunya district, southeast Nigeria.

The HI distribution in sachet water at the sampling locations followed the descending order of Obantoko > Makun-Sagamu > Asero > Isolu > Camp > Iberekodo > Obada. Children were at two times more adverse health risk than adults.

4.3.2. Cancer Risk

The CRs of Ni and Co revealed probable development of cancer by consumers of the sachet water. Research by the International Agency for Research on Cancer (IARC) based on animal data suggests possible human carcinogenicity from Co [42]. The carcinogenic effects of Co and Ni were established in a past study by Taiwo et al. [28] on different drink samples from Abeokuta, Ogun state, Nigeria. Furthermore, the carcinogenic adverse effects of Ni have been documented in groundwater samples from Onitsha and Lagos, Nigeria [51,52]. In 2015, cancer was responsible for 8.8 million global deaths, of which 70% occurred in low- and middle-income countries [53].

4.4. Regression Analysis between WQI and Health Risk

Even though Mn appeared to contribute the most to both the WQI and HI, the regression model revealed a very weak non-significant association, probably due to the other parameters involved in the computation. For CR, none of the carcinogenic metals was included in the WQI estimate, and they are thus weakly related. Despite being weak, the positive correlation that exists in this model indicates a probable influence of the packaged/sachet water WQI on the health of the consumers. Similarly, the past study of Ayejoto et al. [7] reported a positive association between WQI and the health risk indices of contaminated water resources from the Ojoto area, southeast Nigeria. The regression model of the WQI versus health risk suggests safe consumption of the packaged/sachet groundwater in the study area.

5. Conclusions

The present study evaluated the physical and chemical constituents of packaged groundwater collected from seven different sites/factories in Abeokuta and Sagamu, Ogun State, Nigeria. In addition, the water quality index (WQI) and implications for human health risk were assessed. The study established good and excellent water quality for the analyzed packaged groundwater, with WQI values generally less than 100. The health risk assessment revealed non-carcinogenic hazard quotients (HQs) greater than 1.0 for Ca, Mn, Mo, and Cu at some sampling sites, thereby establishing that probable deleterious health implications could arise through ingestion of the sachet water samples. Ca was the highest contributor to the non-carcinogenic adverse health effects in water samples. The sum of HQs (or HI) greater than 1.0 suggests cumulative adverse impacts. The cancer risk (CR) data indicated values higher than the acceptable limit of 1 × 10⁻⁴ for Co (at all the monitoring sites) and Ni (at four sites). The health risk data showed that the sachet water is unsafe for consumption. However, the human carcinogenic properties of Co and Ni are yet to be ascertained. Moreover, most of the metals that contributed to the total non-carcinogenic adverse effects are not toxic. Furthermore, the regression analysis showed very weak relationships between WQI and both HI and CR, thereby establishing less serious health implications for the packaged/sachet groundwater samples. For sustainable consumption of the packaged/sachet groundwater in the study area, periodic monitoring and comprehensive treatment, especially for toxic metals, is recommended.