Health Risk Assessment of Chemical Elements in Drinking Water Consumed in a Brazilian City Impacted by Mining Activities

Abstract

This study evaluates the non-carcinogenic risk associated with chemical elements in drinking water in Jequié, Brazil, where mining activities occur. However, intensive mineral exploration, especially of metals such as vanadium (V), manganese (Mn), nickel (Ni), and chromium (Cr), has raised concerns about potential contamination. Water samples were collected for this research, and chemical analyses were conducted to quantify inorganic contaminants. Arsenic, cadmium, chromium, copper, mercury, manganese, nickel, lead, uranium, vanadium, and zinc were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The following maximum concentrations (μg L⁻¹) were obtained: As (0.36), Cd (0.76), Cr (5.5), Cu (10.6), Hg (1.7), Mn (1.3), Ni (6.7), Pb (10.1), U (0.22), V (1.9), and Zn (175). Non-carcinogenic and carcinogenic risks, such as Estimated Weekly Intake (EWI), Target Hazard Quotient (THQ), and Cancer Risk (CR), were evaluated. In one of the 30 samples analyzed, the Pb concentration exceeded the regulatory limits established by Brazilian legislation. The results highlight the importance of continuous monitoring and effective management of water quality in areas impacted by mining to protect local community health and ensure the sustainable use of water resources. The study concludes that, in general, no non-carcinogenic risks were identified for adults or children.

1. Introduction

Jequié is located in the southwest of Bahia, Brazil, and plays a vital role in the region’s economy and culture. With an estimated population of 160,000, the city has shown constant growth, driven by commerce, services, and its strategic location in the state. The region’s semi-arid climate and rugged relief, composed of mountains and plains, are striking characteristics. These factors influence economic activities and challenges related to water supply and environmental management [1,2,3].

Jequié’s water supply is mainly supplied by the Contas River, which originates in Chapada Diamantina and flows for about 600 km to the Atlantic Ocean. The river supplies water for drinking, agriculture, and industry. The city also has the Pedras Reservoir, a vital infrastructure that helps regulate water flow and meets the region’s water needs. Water treatment and distribution are handled by a local sanitation company committed to ensuring quality and safety. Periods of severe drought, common in the semi-arid region, threaten water availability. Therefore, managing water resources efficiently remains a constant challenge, especially amid increased demand driven by population growth and expanded economic activities [4,5].

The Jequié region is situated within the São Francisco Craton, one of Brazil’s oldest geological formations. It mainly consists of metamorphic and igneous rocks [6,7]. This geological setup supports the presence of significant mineral deposits, which have attracted extensive mineral exploration. The leaching of pollutants into groundwater and surface waters, such as the Rio de Contas, poses a direct threat to the drinking and agricultural water quality used by the local population.

Research conducted in the Jequié region has detected and evidenced the presence of inorganic contaminants (Cu, Cd, Mn, Ni, Pb, and V) in water and soil samples [8,9,10,11,12]. These elements, even at low concentrations, can have long-term adverse effects. Manganese, for example, is essential in small amounts, but it can cause neurological problems at high levels. Nickel is known for its carcinogenic potential, while vanadium and chromium can cause damage to the respiratory and renal systems. Lead, in turn, is widely recognized for its toxic effects, which can affect the central nervous system in addition to causing anemia, hypertension, and other cardiovascular disorders. Vanadium, although less discussed than the previous ones, has toxicity at high levels and is associated with adverse effects on the respiratory and renal systems [13,14,15,16].

The presence of contaminants in the springs used for supply requires ongoing monitoring [9,17,18]. Additionally, it is vital to conduct epidemiological studies to assess potential health impacts on the population, particularly in communities near mining areas [19,20]. The combination of economic growth, pressure on natural resources, and the environmental effects of mining presents significant challenges. Implementing effective public policies and enforcing strict oversight of mining activities are essential for minimizing environmental impacts. Measures such as restoring degraded areas, properly managing mining waste, and promoting sustainable practices can help reduce contamination risks. Moreover, investments in sanitation infrastructure and water treatment technologies are crucial to maintaining the community’s water quality.

The control of drinking water quality in Brazil is mainly overseen by the National Water Agency and the Ministry of Health, with the enforcement of specific standards to ensure the potability of the water supplied to residents. Ordinance No. 2914/2011 of the Brazilian Ministry of Health establishes potability standards, including limits on chemical, microbiological, and physical substances, to ensure that water is safe and poses no health risks [21]. Brazil employs a network of treatment and monitoring plants to assess water quality and to track contaminants, including fecal coliforms, heavy metals, and other pollutants. Additionally, state and municipal initiatives support federal efforts by deploying advanced purification technologies and distribution systems to reduce losses and enhance access, particularly in remote areas or regions with limited water resources, such as mining areas and regions with intensive agriculture [22,23].

The concept of carcinogenic and non-carcinogenic indices is vital for evaluating health risks from chemical exposure, especially in urban or rural areas with industrial activity [24]. The carcinogenic index indicates a chemical’s ability to cause cancer in humans based on epidemiological and toxicological data. Known carcinogens, such as hexavalent chromium, arsenic, and benzene, are assessed by organizations such as the International Agency for Research on Cancer (IARC), which classifies these substances according to risk levels [25]. Conversely, non-carcinogenic indices measure adverse effects that do not involve cancer development, focusing on toxicity thresholds for systemic or organ-specific effects. These indices, including the hazard quotient (HQ) and hazard index (HI), help determine the likelihood of health effects from substances such as fluoride, nitrate, or lead [25,26,27]. Regarding drinking water, the US Environmental Protection Agency (USEPA) sets reference doses for these contaminants, providing essential benchmarks for evaluating potential health risks from daily water intake.

Research on trace metals in drinking water and their associated health risks has been conducted across various regions worldwide, reflecting a growing global concern about water safety and long-term exposure to potentially toxic elements. Studies in China have examined heavy metal levels and health risk factors in urban tap and groundwater sources, showing the presence of multiple trace elements in drinking water [28]. Similar research in India identified high levels of arsenic, lead, and other toxic metals in groundwater, with health risk assessments indicating dangers, especially for children and vulnerable populations [29]. In Brazil, evaluations of metal-contaminated groundwater near landfills revealed that prolonged consumption of contaminated water could pose non-carcinogenic and carcinogenic risks to residents [30]. Turkish studies also observed spatial and temporal variations in toxic metal levels and associated health risks, highlighting that both non-cancer and cancer risks can differ significantly within regions [31]. Research in Iran on tap and groundwater has identified various trace metals and provided risk assessments that guide mitigation efforts [26,27]. Although localized studies are emerging, comprehensive research combining detailed chemical analysis with systematic health risk evaluations remains limited in many parts of the world. The evidence emphasizes the need for ongoing monitoring and tailored regional assessments to enhance water management and safeguard public health.

This study reports the detection of arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel, vanadium, uranium, and zinc in drinking water samples consumed in Jequié, Brazil. The technique used was inductively coupled plasma mass spectrometry (ICP-MS), and the results were assessed based on non-carcinogenic and carcinogenic risk standards set by the United States Environmental Protection Agency (USEPA) and the World Health Organization (WHO), including their regulatory limits.

2. Materials and Methods

2.1. Study Area

Jequié is in southwestern Bahia, Brazil, and is surrounded by other cities that process manganese, uranium, vanadium, and nickel. The region’s water supply is drawn from the Rio de Contas, which is affected by local mining activities. A map of the study area, including the geographical location of Jequié and the sampling points, is shown in Figure 1.

2.2. Collection and Sample Preparation

Thirty drinking water samples were collected in different city neighborhoods and places with a large flow of people, such as restaurants, bars, schools, universities, public institutions, medical centers, pharmacies, and supermarkets. Sampling was conducted over three consecutive days, on 25, 26, and 28 October 2024, during which 30 water samples were collected. These samples were immediately acidified with bidistilled nitric acid (pH < 2) to preserve dissolved metals and prevent adsorption onto container walls. Before instrumental analysis, the samples were filtered through a 0.45 μm cellulose membrane to remove particulate matter. After filtration, the samples were transferred to clean plastic bottles and refrigerated at 4 °C until analysis.

2.3. Determination of the Chemical Elements Using ICP-MS

The multi-elemental determination was performed using an Agilent 8800 Triple Quadrupole ICP-MS/MS system (Agilent Technologies, Santa Clara, CA, USA) equipped with a Micromist nebulizer (Glass Expansion, Melbourne, VIC, Australia). Depending on the analytes of interest, the equipment operated in “No gas” mode or used the collision/reaction cell in “He” mode. The specific operating conditions employed are detailed in Table S1. Instrument control, data acquisition, and data processing were carried out using MassHunter Workstation software, version 4.5 (Agilent Technologies).

All the reagents used were analytical grade. Ultrapure water (18.2 MΩ·cm) was obtained from a Milli-Q purification system (Millipore-Merck, Darmstadt, Germany) and used for the preparation of all standard solutions. Suprapur^® grade nitric acid (65.0%, Merck, Darmstadt, Germany) was used for sample and standard preparation. For the optimization of the ICP-MS/MS, a Tuning/Start-up solution containing 10 μg L⁻¹ of Ce, Co, Li, Tl, and Y in HNO₃ 2% (Agilent Technologies) was used to guarantee the parameters CeO⁺/Ce⁺ < 2% and Ce₂⁺/Ce⁺ < 3%. Ge, In, and Tl were used as internal standards to correct for possible instrumental deviations and matrix effects.

The calibration solutions, with concentrations ranging from 0.1 to 100.0 μg L⁻¹, were prepared by appropriately diluting individual standard solutions of 10.0 mg L⁻¹. In addition, a 1.0 mg L⁻¹ solution of Ge, In, and Tl was used as the internal standard for all analyses. The precision and accuracy of the method were confirmed by analyzing the certified reference material EnviroMAT-Drinking Water (EP-H-3, SCP Science, ref. 140-025-032, Quebec, QC, Canada).

2.4. Human Health Risk Quantification

Health risk assessment of chemical elements in drinking water was calculated using established indices [25]. The single index that assesses the toxicity of a unique chemical element, such as Estimated Weekly Intake (EWI), Target Hazard Quotient (THQ), and Cancer Risk (CR), was calculated in this work. Integrated indices, such as the Hazard Index HI-THQ and HI-CR, were also calculated by summing the respective indices for each element. The terms used in the calculus of the index, along with their conventional values, are listed in

Table 1. Parameters and conventional values used in equations for health risk assessment.

Parameter	Definition	Unit	Adult	Children
C	Concentration of the chemical element	µg L−1	-	-
IR	Water ingestion rate	L week−1	17.5	5.0
BW	Body weight	kg	70	30
EF	Exposure frequency	day year−1	350	350
ED	Exposure duration	year	30	6
RD	Oral dose a	mg BWkg−1 day−1	-	-
AT	Averaging time	day	ED × 365	ED × 365
CPSo	Oral cancer slope factor b	mg kg day−1	-	-
THQi	Target hazard quotient for an individual contaminant	µg L−1 day−1	-	-
CRi	Carcinogenic risk for an individual contaminant	-	-	-

^a: RD values (mg BW kg⁻¹ day⁻¹) are specific for each chemical element: arsenic (0.0003), cadmium (0.001), chromium (0.0015), copper (0.00004), lead (0.0004), manganese (0.00014), mercury (0.0003), nickel (0.0002), uranium (0.000003), vanadium (0.000003), and zinc (0.0003); ^b: CPSo values (mg kg day⁻¹) are also specific: arsenic (1.5), cadmium (6.1), chromium (0.5), copper (1.5), lead (0.0085), nickel (0.84).

[25,32].

EWI is an index used to estimate the weekly intake of a particular contaminant through drinking water. It is expressed in units such as micrograms (µg) per kilogram of body weight per week or µg per liter of water. The calculation is based on average water consumption rates and the contaminant concentration in the water. EWI assesses human exposure to potentially harmful substances and compares them against limits established by regulatory agencies [33]. If the EWI is below these thresholds, the contaminant is unlikely to pose a health risk under standard consumption patterns [25]. Equation (1) was used to calculate EWI.

$$\mathrm{EWI}={\displaystyle \frac{\mathrm{C} \times \mathrm{IR}}{\mathrm{BW}}}$$

(1)

Another parameter used to assess human health risks is THQ, calculated using Equation (2) [34]. This dimensionless parameter evaluates the non-carcinogenic risk associated with the intake of contaminants, such as heavy metals, through various exposure pathways, including drinking water. THQ provides a quantitative indication of whether the exposure level to a particular contaminant exceeds the reference dose (RfD) over a given time. A THQ value less than 1 indicates that the exposure is unlikely to pose significant non-carcinogenic health risks. Conversely, a THQ value of 1 or greater suggests that exposure may lead to adverse health effects, warranting further investigation or the implementation of mitigation measures.

$$\mathrm{THQ}={\displaystyle \frac{ \mathrm{EF} \times \mathrm{ED} \times \mathrm{IR} \times \mathrm{C}}{\mathrm{AT} \times \mathrm{BW} \times \mathrm{RD}}} \times 1.0 \times {10}^{-3}$$

(2)

CR estimates the likelihood of an individual developing cancer over a lifetime due to exposure to specific carcinogens, such as heavy metals or other toxic substances, through pathways like drinking water [25,35,36]. It provides a quantitative measure of carcinogenic risk, with values interpreted as follows: CR < 1.0 × 10⁻⁶ is considered negligible, indicating an extremely low probability of developing cancer. CR between 1.0 × 10⁻⁶ and 1.0 × 10⁻⁴ falls within an acceptable or tolerable risk range, depending on regulatory standards. CR > 1.0 × 10⁻⁴ suggests a significant cancer risk, often requiring intervention or mitigation measures. As a critical tool in environmental and public health risk assessments, CR helps prioritize contaminants for regulation and remediation based on their potential to cause cancer in exposed populations. Its application ensures that public health protections align with acceptable safety thresholds while effectively addressing significant risks. The calculation of CR is established by Equation (3).

$$\mathrm{CR}={\displaystyle \frac{ \mathrm{EF} \times \mathrm{ED} \times \mathrm{IR} \times \mathrm{C} \times \mathrm{CPSo}}{\mathrm{AT} \times \mathrm{BW}}} \times 1.0 \times { 10}^{-3}$$

(3)

The Hazard Index (HI) is a cumulative metric used to assess the overall risk from exposure to multiple contaminants, calculated as the sum of individual indexes for each contaminant [37,38]. HI-THQ is the sum of individual THQs for non-carcinogenic contaminants (Equation (4)) and assesses whether combined exposure to different substances might exceed safe levels and pose a risk to human health. If HI-THQ < 1, the combined exposure is unlikely to cause significant non-carcinogenic health risks. At the same time, if HI-THQ ≥ 1, there may be a risk of adverse health effects due to cumulative exposure, warranting further investigation. The Hazard Index for Carcinogenic Risk (HI-CR) is used to evaluate the cumulative cancer risk from exposure to multiple carcinogens, calculated as the sum of individual Carcinogenic Risk (CR) values for each contaminant (Equation (5)). Interpretation of HI-CR follows these guidelines: HI-CR < 1 × 10⁻⁶ indicates negligible cancer risk, HI-CR between 1 × 10⁻⁶ and 1 × 10⁻⁴ represents an acceptable or tolerable risk, and HI-CR > 1 × 10⁻⁴ signifies a significant cancer risk, requiring mitigation.

$$\mathrm{HI}-\mathrm{THQ}=\mathsf{\sum } {\mathrm{THQ}}_{\mathrm{i}}$$

(4)

$$\mathrm{HI}-\mathrm{CR}=\mathsf{\sum } {\mathrm{CR}}_{\mathrm{i}}$$

(5)

3. Results

The recommendations for ICP-MS analyses followed the IUPAC guidelines, ensuring reliable, robust results. All measurements used 72Ge, 115In, and 205Tl as internal standards, selected to correct for instrumental drift and matrix effects. Calibration curves were prepared with at least five concentration levels, and the correlation coefficients (R2) were checked to verify linearity across the analytical range.

The limits of detection (LOD) and quantification (LOQ) were determined using the standard IUPAC equations, LOD = 3s/α and LOQ = 10s/α, where s represents the standard deviation of ten replicate measurements of the analytical blank, and α is the slope of the calibration curve for each analyte. Method accuracy was confirmed with the certified reference material EnviroMAT-Drinking Water, and Table S2 summarizes the isotopes monitored, acquisition mode, correlation coefficients, instrumental detection capabilities, and CRM recoveries.

Thirty drinking-water samples were collected, acidified, and filtered before analysis. The concentrations of arsenic, cadmium, copper, chromium, mercury, manganese, nickel, lead, vanadium, uranium, and zinc were determined by ICP-MS. Table S3 presents the elemental concentrations (µg L⁻¹) for all samples.

Arsenic concentrations ranged from 0.08 to 0.62 µg L⁻¹, with an average of 0.42 µg L⁻¹, all values remaining below the limits established by Brazilian and international regulations (

Table 2. Guideline values for maximum residue limits (μg L⁻¹) of metals in drinking water. ^a: Ordinance MS No. 2914 of 12 December 2011, Brasilia [25]; ^b: Directive on the quality of water intended for human consumption [39]; ^c: W. H. Organization, Guidelines for drinking-water quality [33]; ^d: EPA, National primary drinking water regulations [32].

Parameter	Brazilian Government a	EU b	WHO c	EPA d	This Work
					Minimum	Average	Maximum
As	10	10	10	10	0.08	0.42	0.62
Cd	3	5	3	5	0.01	0.11	0.76
Cr	50	50	-	100	0.03	1.21	5.51
Cu	2000	2000	2000	1300	0.00	4.40	10.57
Total Hg	1	1	1	2	0.00	0.28	1.72
Mn	100	50	80	50	0.00	1.03	2.45
Ni	70	20	-	20	0.05	1.93	6.67
Pb	10	10	10	10	0.35	2.26	10.07
U	3	-	-	-	0.05	0.71	1.65
Zn	5000	-	-	5000	0.00	33.19	175.00

). Cadmium levels ranged from 0.01 to 0.76 µg L⁻¹, averaging 0.11 µg L⁻¹, and were also below permitted thresholds. Chromium concentrations ranged from 0.03 to 5.51 µg L⁻¹, with an average of 1.21 µg L⁻¹, values that remain substantially below the Brazilian limit (50 µg L⁻¹).

Copper concentrations ranged from 0.01 to 10.57 µg L⁻¹, with an average of 4.40 µg L⁻¹, which is consistent with regulatory requirements. Mercury levels ranged from 0.01 to 1.72 µg L⁻¹, with an average of 0.28 µg L⁻¹; however, one sample exceeded the maximum limit of 1.0 µg L⁻¹, indicating a point-specific contamination. Manganese concentrations ranged from 0.02 to 2.45 µg L⁻¹, averaging 1.03 µg L⁻¹, while nickel concentrations varied between 0.05 and 6.67 µg L⁻¹, with an average of 1.93 µg L⁻¹.

Lead concentrations ranged from 0.35 to 5.67 µg L⁻¹ across 29 samples, with a single sample at 10.70 µg L⁻¹, exceeding both Brazilian and international limits. Zinc concentrations were more variable, ranging from 3.23 to 175.00 µg L⁻¹, with an average of 33.19 µg L⁻¹. Vanadium ranged from 0.05 to 1.65 µg L⁻¹ (average 0.19 µg L⁻¹), and uranium ranged from 0.01 to 0.22 µg L⁻¹ (average 0.10 µg L⁻¹).

The toxicity assessment of these elements was conducted using Equations (1)–(3) to calculate the Estimated Weekly Intake (EWI), Target Hazard Quotient (THQ), and Cancer Risk (CR). Calculations were performed assuming an average weekly water consumption of 17.5 L for adults (70 kg) and 7.5 L for children (30 kg). Health risk indices were estimated for As, Cd, Cu, Cr, Hg, Mn, Ni, Pb, V, U, and Zn using the maximum measured concentrations to represent worst-case exposure scenarios, a conservative and widely accepted approach in human health risk assessment. The resulting EWI, THQ, and CR values are presented in Tables S4, S5, and S6, respectively. A summary of worst-case exposure results is shown in

Table 3. Health risk indices calculated using maximum concentration values (worst-case exposure scenario). EWI reference values are based on the tolerable weekly intake (TWI); THQ reference value = 1; CR acceptable risk range = 10⁻⁶–10⁻⁴.

Chemical Element	Content (µg L−1)	Group	EWI	THQ	CR
As	0.62	Adult	0.15	0.074	3.3 × 10−5
		Child	0.36	0.17	7.8 × 10−5
Cd	0.76	Adult	0.19	0.027	1.7 × 10−4
		Child	0.45	0.064	3.9 × 10−4
Cr	5.51	Adult	1.38	1.3 × 10−4	9.8 × 10−5
		Child	3.22	3.1 × 10−4	2.3 × 10−4
Cu	10.57	Adult	2.64	0.009	not regulated
		Child	6.16	0.022	not regulated
Hg	1.72	Adult	0.43	0.20	no data available
		Child	1.00	0.48	no data available
Mn	2.45	Adult	0.61	0.63	not regulated
		Child	1.43	1.46	not regulated
Ni	6.67	Adult	1.67	0.012	2.0 × 10−4
		Child	3.89	0.028	4.7 × 10−4
Pb	10.07	Adult	2.52	0.90	3.1 × 10−6
		Child	5.88	2.10	7.1 × 10−6
U	0.22	Adult	0.055	0.0026	no data available
		Child	0.13	0.0062	no data available
V	1.93	Adult	0.48	0.023	not regulated
		Child	1.12	0.054	not regulated
Zn	175	Adult	43.8	0.021	not regulated
		Child	102	0.049	not regulated

, where values exceeding the corresponding reference or guideline limits are highlighted in bold.

4. Discussion

The highest concentrations of heavy metals were observed in samples A1, A5, A9, and A29. The study area is influenced by mining and mineral processing activities, which may contribute to the regional geochemical background and represent potential sources of metal inputs. However, elevated concentrations in drinking water may also be influenced by local factors, including water distribution infrastructure, pipe and storage system corrosion, and site-specific environmental conditions. Therefore, while mining activities cannot be ruled out, the observed spatial variability suggests that multiple sources and processes may contribute to metal occurrence, highlighting the need for further investigation to better identify contamination pathways.

The estimated weekly intake (EWI) values calculated using maximum concentrations remained below the established safety limits for all analyzed elements, indicating that weekly exposure to drinking water is generally low and unlikely to pose significant health risks under typical consumption. These results suggest that, for most elements, the observed concentrations are consistent with natural background levels or diffuse anthropogenic inputs rather than acute pollution sources.

Regarding non-carcinogenic risk, Target Hazard Quotient (THQ) values were below 1 for most elements, even under worst-case exposure scenarios, indicating a low probability of adverse non-carcinogenic effects. An important exception was observed for lead (Pb), for which the THQ exceeded unity in the child exposure group (THQ = 2.10), suggesting a potential non-carcinogenic health concern for children. This finding reflects children’s greater vulnerability due to their lower body weight and higher intake-to-body-mass ratio.

Carcinogenic risk (CR) values varied widely across elements and exposure groups. Although some CR values fell within the negligible risk range (<1 × 10⁻⁶), others exceeded the commonly accepted upper threshold of 1 × 10⁻⁴, particularly under worst-case exposure conditions. These results indicate that certain elements may pose potential long-term carcinogenic risks, especially for children, and therefore warrant attention in risk management and monitoring programs.

An integrated assessment of cumulative exposure further supports these observations. Based on maximum concentrations, the total non-carcinogenic risk (ΣTHQ) was 0.99 for adults, remaining below the reference threshold, whereas for children ΣTHQ reached 4.43, indicating a potential health concern under worst-case conditions. Similarly, the total carcinogenic risk (ΣCR) was estimated at 5.3 × 10⁻⁴ for adults and 1.2 × 10⁻³ for children, exceeding the commonly accepted risk range and driven mainly by Cd, Cr, and Ni. The corresponding total estimated weekly intake (ΣEWI) values were 54.9 µg week⁻¹ for adults and 127.8 µg week⁻¹ for children. Although detailed calculations are provided in the Supplementary Materials, including these cumulative indices in the main text emphasizes the importance of combined exposure in health risk assessment.

Overall, drinking water samples generally complied with national and international potability standards. Nevertheless, isolated exceedances of mercury and lead concentrations, along with elevated risk indices under worst-case scenarios, highlight vulnerabilities in the water supply and distribution system. These findings underscore the need for targeted monitoring, source identification, and regular evaluation of water treatment and distribution infrastructure to ensure long-term safety, particularly in regions affected by mining activities.

5. Conclusions

This study provided a comprehensive assessment of human health risks associated with chemical elements in drinking water consumed in Jequié, a city in a region influenced by mining activities. Trace elements such as Cu, Cd, Mn, Ni, Pb, and Zn were detected in all samples, with isolated exceedances of regulatory limits observed for lead. Although most non-carcinogenic risk indicators remained below critical thresholds, the Target Hazard Quotient for lead exceeded 1 for the child exposure group under worst-case conditions, indicating a potential non-carcinogenic health concern. Additionally, carcinogenic risk estimates for certain elements exceeded commonly accepted benchmark values, highlighting the importance of long-term exposure assessment.

These findings show that, although drinking water quality in the study area generally meets potability standards, localized contamination and elevated health risk indices warrant continued monitoring and more detailed investigations into contamination sources. In mining-affected regions such as Jequié, integrating routine chemical monitoring with risk assessment tools is essential to support effective water management strategies, mitigate environmental impacts, and safeguard public health.