Cancer and Non-Cancer Risk of Arsenic in Drinking Water: A Case Study

AUTHORS

Yadollah Ghafuri 1 , 2 , Hossein Kamani 3 , Edris Bazrafshan ORCID 4 , Zahra Atafar 5 , Mohammad Khazaie 2 , Amir Hossein Mahvi 5 , 6 , *

1 Department of Environmental Health Engineering, School of Public Health, International Campus, Tehran University of Medical Sciences, (IC-TUMS) Tehran, Iran

2 Environmental Research Center, Qom University of Medical Science, Qom, Iran

3 Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran

4 Health Sciences Research Center, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran

5 Department of Environmental Health Engineering, School of Public Health , Tehran University of Medical Sciences, Tehran, Iran

6 Centers for Solid Waste Research, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran

How to Cite: Ghafuri Y, Kamani H, Bazrafshan E, Atafar Z, Khazaie M, et al. Cancer and Non-Cancer Risk of Arsenic in Drinking Water: A Case Study, Health Scope. 2017 ; 6(4):e13013. doi: 10.5812/jhealthscope.13013.

ARTICLE INFORMATION

Health Scope: 6 (4); e13013
Published Online: November 21, 2017
Article Type: Research Article
Received: May 11, 2017
Accepted: September 11, 2017
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Abstract

Arsenic is a toxic element, which is found naturally in water sources. Due to its high toxicity it has become a serious problem in drinking water sources and also affects the health of communities. Therefore, in the present study, risk estimation and the probability of adverse health effects of exposure to arsenic from drinking water was evaluated in the rural areas of Qom province. Water samples were taken from 44 rural areas with regard to the number of rural areas and also the type of water distribution systems. The intensity, duration and frequency of exposure to arsenic in drinking water were determined. Then the hazard quotient and cancer risks ware calculated. Results showed that more than 16% of the rural population was exposed to arsenic with level above 10 μg/L in the rural regions of Kahak County (10 ± 6.29 μg/L). Results of risk assessment showed that hazard quotient (HQ) were 1.7 and 2, while the cancer risk (CR) were 76 × 10-5 and 42 × 10-4 for 2 groups of age 1 and 2, respectively. The results indicated that the hazard quotient is higher than 1 (HQ > 1) for group 1 and group 2. For carcinogenic effects, the study indicated that the population in the Kahak region are exposed to arsenic in drinking water with the concentration of > 10 µg/L and they are at a very high risk for cancer, due to the fact that the cancer risk for the 2 groups are more than 7.6 and 42 times the environmental protection agency (EPA) criteria, respectively. Therefore it is recommended that at first, the source and water supply system in Kahak region is to be substituted with safe drinking water and to provide health facilities and screening tests for exposed populations.

Keywords

Risk Cancer Arsenic Drinking Water Risk Assessment

Copyright © 2017, Journal of Health Scope. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

1. Introduction

It is estimated that 200 million people throughout the world are exposed to arsenic in drinking water that exceed the recommended limit of 10 µg/L as set out in the guidelines of the world health organization (WHO) (1). Arsenic (As) is a toxic element, which is found naturally in water sources, soil, and sediments (1, 2). The nature of the soil parent material appears to be the main factor determining the As concentration in soils, although due to its low supergene mobility, the soils are slightly enriched in As compared with their soil parent rocks (3, 4). The consumption of arsenic from contaminated water may adversely affect human health. The international agency for research on cancer (IARC) classifies (As) as a group 1 based on epidemiological studies (5). The exposure of arsenic from drinking water has been reported in many countries such as: Taiwan, Argentina, Chile, Mexico, India, Bangladesh, China, Vietnam, and Cambodia. The most common sign of exposure to arsenic is hyper pigmentation, especially on the trunk, and keratosis on the palms and soles. These skin lesions generally develop within 5 - 10 years after the initial exposure, although shorter latencies have been reported. Many other signs and symptoms have also been noted such as chronic cough, crepitation’s in the lungs, diabetes mellitus, hypertension, and weakness (1, 6).

The WHO guideline and permissible limit by health ministry of Iran for Arsenic in drinking water is 10 μg/L (6). Qom province is one of the central regions in Iran with a harmful as well as dry climate and with many economic and cultural potentialities. The rural population of Qom province is about 84000 inhabitants, where water supply systems have considerable challenges regarding water quality and quantity. High concentration of As and the physico-chemical parameters in groundwater in rural drinking water in Qom province has been previously reported. Mining activity and geology of the study area including rural county of Qom province and possible leaching of As in ground water has an important factor in the health of inhabitants (1, 2). The present study addresses these through a human health risk assessment in the rural of Qom province for exposure by arsenic in drinking water.

2. Methods

2.1. Description of Study

Methodology of the study was anticipated in 2 phases including: environmental monitoring of arsenic in rural water supply and the arsenic health risk assessment in rural regions having concentration of arsenic higher than Iranian national drinking water standard (> 10 µg/L). The limitation of the Qom rural with consideration to the Qom province contains 5 counties and 180 rural regions that are presented in Figure 1.

Location of Studied Area and Sampling Points
Figure 1. Location of Studied Area and Sampling Points

2.2. Sampling Analysis

Water samples were taken from 44 rural areas of the Qom province with regard to the number of rural areas and also the type of water distribution systems. Factors such as the kind of water sources were considered. The sampling period was from May through October 2016. The information including sample code, name of sampler, the geographical location of sampling, and sampling date were recorded for each sample. Physical parameters such as: alkalinity, electrical conductivity, temperature, and pH were measured (7-9).

An automatic absorption spectrometer (AAS) equipped with graphite furnace was applied for sample measurements. Hydrochloric acid (0.02 N) was applied to preserve the samples prior to delivery to the laboratory. The analytical LOD, calculated as 3 times the standard deviation (SD) of the lowest detectable calibration standard (0.2 μg/L), was determined. The total alkalinity and total hardness of the samples is being determined by standard titrimetric methods (7-9).

2.3. Human Health Risk Assessment

Considering the process of human health risk assessment, 4 steps were taken including hazard identification, dose-response assessment, exposure assessment, and risk characterization (9). In the risk assessment, addressing uncertainties is necessary in order to avoid inaccurate or biased estimates. Therefore Monte Carlo simulation and sensitivity analysis were implemented using the @risk software (version 6.0, Palsida Corporation, USA) (10).

2.3.1. Hazard Identification

In this study, hazard identification related to the concentration of arsenic that must be concern and adverse effects were determined.

2.3.2. Dose- Response Assessment

Dose-response assessment for ingested toxicants in terms of reference dose (RfD) for non-cancer effects and cancer slope factor (CSF) for cancer effects was extracted by Integrated information system (IRIS), where the toxicity reference dose (RfD) is 0.0003 mg/kg/day and cancer slope factor (CSF) for arsenic is 1.5 mg/kg/day (11, 12).

2.3.3. Exposure Assessment

The concentrations of arsenic in water are determined from rural water supply distribution. In addition, the intensity, duration, and frequency of exposure to arsenic in drinking water were assessed by the questionnaire and interview with settlements of rural regions. The interview was conducted to collect all exposure factors. A bout questionnaire questions that used to estimate of intake contain body weight, the duration of frequency, and the exposure duration. The reliability of the questionnaire by alpha coefficient 0.87 was determined. With consideration, arsenic enters into the human body through several pathways; the average daily dose (ADD) through drinking water intake was calculated.

Average daily dose (ADD) for deterministic risk assessment and lifetime average daily dose (LADD) for cancer effects were calculated according to the following equations (13, 14):

At above equation C: represent the amount of Arsenic in rural drinking water (µg/L)

IR: water consumption for individuals less than 13 years old 1 lit/day and anyone older than this age 2 lit/day was considered.

ED: exposure duration with regard to the age range of population containing 0 - 14 and 15 - 65, respectively.

EF: exposure duration (365 day/year)

BW: body weight for people under 15 years old. The weight of 50% of the corresponding WHO age-weight curve was considered for 15 years old and older as 70 kg.

AT: average life time (ED × 365 days/years)

ADD and LADD were expressed in mg/kg/y

2.4. Risk Characterization

Risk characterization was carried for deterministic risk assessment by hazard quotient (HQ) and cancer effects. Hazard quotient (HQ) was estimated through Equation 3:

Cancer risk (CR) was calculated by the following equation:

For cancer risk results, the acceptable level of 1 case per 10,000 is set in this study.

3. Results

3.1. Arsenic Concentration in Rural Water Supply System

Results of study showed that the concentrations of arsenic in rural water supply system are 0 to 30 μg/L (mean value of 3.16 μg/L and σ = ± 4.86) as shown in Table 1. More than 16% of the rural population was exposed to arsenic with level above 10 μg/L and 70% of the population was exposed to arsenic with levels 1 to 10 μg/L.

Rural regions of Kahak County did not meet the standard for concentration (mean value of 10.12 μg/L and σ = ± 6.29). The rate of hardness and alkalinity in the Kahak County (mean value of 371 mg/L, σ = ± 143 and 231 mg/L, σ = ± 74.1) was determined, respectively. The results of water sampling from 5 counties of Qom province consisted of Kahak, Salafchegan, Markazi, Dastjerd, and Jafarieh about physico-chemical parameters (pH, As, Alkalinity and Hardness) are also represented in Table 1.

Table 1. pH, Alkalinity, Hardness an As in Collected Samples
CountyRural RegionpHAs, ppbHardnessAlkalinity
MarkaziQomrud7.952313150
Ganavat6.3129850
Agholak6.90310100
Kalageneshin7.10350260
Eslamabad8.090250150
KahakKahak88290210
Bidhand7.214360213
Fordo7.806245180
Kermejagan7.648200190
Veshnaveh7.4212294250
Venarch7.8030800450
Khaveh7.5012450290
Khurabad7.903380200
Khadijehkhatun7.1015500280
Abarjes7.7010500250
Siru6.811370220
Virij8.095180140
Dastgerd7.107378167
Verjan7.207310145
Meiam7.4012360190
Zanburak7.5012400280
Salafchegan7.632650310
Rahjerd7.702607308
Tajkhatun8.081100250
Jandab8.302100200
Disijan7.901420210
Senjekan7.702180145
SalafcheganGhalecham7.832470210
Bagheiek7.712450220
Enaiatbeik7.371680240
Khalajabad7.602480250
Iekebagh7.300460270
Jafarieh7.92196180
JafariehPachian7.582220160
Tagharud7.62313140
Dastjerd7.700170210
Ghahan7.550411210
Zizegan7.561100200
Sanavand7.610300240
DastjerdEslamabad7.401350185
Ahmadabad7.661390240
Varzaneh7.201210105
Hasanabad7.521690230
Veshareh7.631210220

3.2. Health Risk Assessment

Considering the results of arsenic concentration in drinking water of the rural population, it is obvious that the major exposure with arsenic in drinking water is related to the region of Kahak County (mean value of > 10 μg/L), which is much higher than the Iranian National drinking water standard and WHO guidance (1). Therefore, the exposure risk assessment was applied for the region of Kahak County. A survey on the demographic categories for amounts of water consumption from the distribution water supply system in Kahak County region was done by applying the exposure parameter and was evaluated from an interview and a structure questionnaire including detailed questions on the variable used to estimate the intake amounts such as: body weight, duration, frequency, and exposure duration. With consideration to most cases, arsenic concentration for all of rural area of Kahak county were not available and therefore we assumed the As concentration value of 30 μg/L, which corresponds to a worst-case scenario (equally of As concentration of venarch region in the Kahak county).

The results determined that 2 group for exposure dose must be considered. Group 1: exposed population containing individuals from 0 - 14 years old with the annual water intake of 0.5 L/d. Group 2: the exposed population with the average age ranged from 15 - 65 years old with the annual intake of 1 L/d. The exposure dose for arsenic in drinking water was calculated for the 2 mentioned groups are represented in Tables 2 and 3.

Table 2. Exposure Dose for Deterministic Effects (Non-Cancer Effects)
GroupC, µg/LIR, L/dBW, kgED, yEF, d/yADD, mg/kg/y
Non-Cancer Effects1300.52973655 × 10-4
230150333656 × 10-4
Table 3. Exposure Dose for Stochastic Effects (Cancer Effects)
GroupC, µg/LIR, L/dBW, kgED, yEF, d/yATLADD, mg/kg/y
Cancer Effects1300.5297365255505.1 × 10-5
230150333652555028 × 10-4

For risk characterization at this study, the deterministic risk assessment (non-cancer effects) and the stochastic risk assessment were estimated. In this method, the protocols and criteria related to USEPA (12) were considered. The results of risk characterization for the 2 groups in this study are represented in Table 4.

Table 4. Outputs of Risk Characterization
GroupNon-Cancer EffectsCancer Effects
ADDHQLADDCR
15.1 × 10-41.75.1 × 10-576 × 10-5
26 × 10-4228 × 10-442 × 10-4

4. Discussion

The results of this study, especially with considering the outputs of risk characterization (Table 3) for non-carcinogenic effects by arsenic in drinking water of Venarch region of Kahak county indicated that the hazard quotient (HQ) for Group 1 and Group 2 is higher than 1 (HQ > 1) and the possibility of risk of disease for 2 groups especially individuals within the age of 15 - 65 years old. Of course, these concentrations of arsenic can cause the adverse health effects on children with the ages lower than 14 years.

In the cancer risk assessment, the cumulative probability of total risk calculated by using the Monte Carlo simulation is shown in Figures 2 and 3. The mean cancer risk calculated for group 1 was 76 × 10-5 based on point estimation, however, as shown in Figure 2, the 90% probability CR for group 1 exposed to As concentration with > 10 µg/L, ranged from 63.5 × 10-5 to 88.5 × 10-5. The mean cancer risk calculated for Group 2 was 42 × 10-5 based on point estimation. In Figure 3, the 90% probability CR for Group 2 exposed to As concentration with > 10 µg/L ranged from 35 × 10-4 to 48 × 10-4.

Cancer Risk Assessment for Group 1
Figure 2. Cancer Risk Assessment for Group 1
Cancer Risk Assessment for Group 2
Figure 3. Cancer Risk Assessment for Group 2

For carcinogenic effects, considering 10-4 as a limit for CR (7, 12, 13), the results are indicated that the individual in the rural regions of Kahak county are exposed to arsenic in drinking water. The concentration of 30 µg/L of arsenic are known to have a very high risk for cancer due to the fact that the cancer risk for the 2 group are more than 7.6 and 42 times the EPA criteria, respectively. With regard to the results of this study, although the low Arsenic exposure by drinking water and with intake rate of (0.5 L/day) and the concentration of arsenic in drinking water was 3 times higher compared to the recommended international standards (10 µg/L) (1), the potential risk for non-carcinogenic effects and carcinogenic effects have been increased.

This result was comparable to the other studies that ar carried out in other countries. In the study of arsenic in drinking water toxicological risk assessment in the North Region of Burkina Faso, arsenic concentration ranged from 0 up to 87.8 micrograms per liter. The risk induced by arsenic for non- cancer effects when children are aged between 0 - 14 are subject to arsenic concentrations below 87 g/L. The risk is huge in all cases and HQ > 1 for carcinogenic effects (13). In another study of a population chronically exposed to arsenic through drinking water from Argentina, a wide range of concentration from non-detectable (ND) to 2000 μg/L, in 68% of the locations of the study, the population had a HQ greater than 1, and the CR ranged between 5 × 10-5 and 2.1 × 10-2 (9). Health risk assessment for exposure to arsenic in drinking water in Hanam Province, Vietnam, showed that arsenic concentrations in tube-well water ranged from 8 - 579 ppb and the skin cancer risk would be 11.5 times higher if the water was not filtered with water induced potential risk for population (15). The results of the study regarding exposure of children to arsenic in drinking water in the Tharparkar region of Sindh, Pakistan, indicated that 2 age groups (5 - 10 and 11 - 14 years) exposed to total arsenic concentration in the groundwater was 6.51 - 9.98 µg/L and in addition, HQ (2.2 - 2.3) was determined (14). Figures 4 and 5 represented the correlation observed between the amount of arsenic concentration versus hardness and alkalinity measured in the rural drinking water of Qom province.

Arsenic Concentration Versus Hardness of Drinking Water in the Kahak County
Figure 4. Arsenic Concentration Versus Hardness of Drinking Water in the Kahak County
Arsenic Concentration Versus Alkalinity of Drinking Water in the Kahak County
Figure 5. Arsenic Concentration Versus Alkalinity of Drinking Water in the Kahak County

The results in Figure 5 (R2 = 0.47, P value < 0.05) and Figure 4 (R2 = 0.51, P value < 0.05) exhibited a small correlation between high levels of arsenic concentration in drinking water of rural regions of Kahak County with a rate of hardness and alkalinity. In the study of Benner et al. statistical analyses reveal that a positive exists between total hardness of groundwater and the arsenic content in it. It is determined that mining activities has an important role in increasing of arsenic concentration (16-18).

5. Conclusions

In this study, the exposure of drinking water was assessed. However, not only water but also the food sources are the major potential source of arsenic exposure in the polluted areas. It is obvious that the mining activities such as magnetic extraction in the rural region of Kahak County induced the increasing of arsenic in drinking water sources.

The lack of local awareness and poor reporting of the health aspects of arsenic in drinking water in Kahak region are the main obstacles for control of adverse effects of arsenic problems. Therefore, it is recommended that for the first time, the source and water supply system in rural region of Kahak is substituted with safe drinking water as well as providing health facilities and screening tests for exposed populations.

Acknowledgements

Footnote

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