|Year : 2017 | Volume
| Issue : 4 | Page : 1019-1023
|Role of reverse osmosis membranes on the concentration fluctuations of heavy metals in used water by dialysis instrument of hemodialysis patients
Meghdad Pirsaheb1, Kiomars Sharafie1, Shahram Naderi2, Hamid Reza Ghafari3, Touba Khosravi1
1 Department of Environmental Health Engineering, Public Health School, Kermanshah University of Medical Sciences, Kermanshah, Iran
2 Department of Environmental Engineering, Islamic Azad University, Hamedan Branch, Hamedan, Iran
3 Department of Environmental Health Engineering, Faculty of Health, Hormozgan University of Medical Sciences, Bandar Abbas; Department Environmental Health Engineering, Public Health School, Tehran University of Medical Sciences, Tehran, Iran
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|Date of Web Publication||5-Oct-2017|
| Abstract|| |
Background: Hemodialysis (HD) patients have poorly functioning kidneys in terms of blood detoxification; therefore, they need regular and continued HD to be able to continue their lives. Objectives: This study was aimed to survey changes in the concentrations of lead, cadmium, chromium, and zinc by seven dialysis instruments at hospitals of Kermanshah Province. Materials and Methods: One hundred and twenty-six samples were collected from three different dialysis cycles and tested using inductively coupled plasma system. Results: Results showed that the mean concentrations of lead, cadmium, chromium, and zinc were 18.53 ± 8.25, 0.706 ± 0.42, 86.06 ± 5.56, and 112.67 ± 63.56 pbb in the feed water of the reverse osmosis (RO) system (tap water), 18.81 ± 5.32, 0.719 ± 0.53, 84.25 ± 2.46, and 43.39 ± 19.4 in the permeated water of the RO, and 12.56 ± 6.32, 1.39 ± 0.87, 66.15 ± 13.54, and 60.38 ± 22.39 in permeated water of the dialysis instrument, respectively. Efficiency of RO in the dialysis instrument was 61.5 and 2.1% for zinc and chromium removal, respectively while this system was not effective in terms of removing lead and cadmium metals. Increases in lead and cadmium levels in the permeated water of the RO system compared to the feed water indicated that the performance of RO was decreased. Conclusions: It can be concluded that lead and cadmium reduction in the permeated water of the dialysis instrument showed that these two dangerous metals were increased in the blood of HD patients, which might be due to the malfunction of RO membrane.
Keywords: Dialysis, heavy metals, instrument, membrane, reverse osmosis
|How to cite this article:|
Pirsaheb M, Sharafie K, Naderi S, Ghafari HR, Khosravi T. Role of reverse osmosis membranes on the concentration fluctuations of heavy metals in used water by dialysis instrument of hemodialysis patients. Ann Trop Med Public Health 2017;10:1019-23
|How to cite this URL:|
Pirsaheb M, Sharafie K, Naderi S, Ghafari HR, Khosravi T. Role of reverse osmosis membranes on the concentration fluctuations of heavy metals in used water by dialysis instrument of hemodialysis patients. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Sep 19];10:1019-23. Available from: http://www.atmph.org/text.asp?2017/10/4/1019/215885
| Introduction|| |
Inter heavy metals with unauthorized range in human body have harmful effects on human health.,
Hemodialysis (HD) patients have poorly functioning kidneys in terms of blood detoxification; therefore, they need regular and continued HD to be able to continue their lives.,, Two lit of drinking water is required per person every day; since any HD patient undergoes HD therapy for 4 h, the amount 300 lit of water is required for him/her. It is notable that the contaminants existing in drinking water may be released to the bloodstream through the digestive tract, whereas during dialysis, contaminants in dialysate are directly released to the bloodstream. Thus, it is vital to observe the quality standards, especially chemical characteristics of dialysate. Dialysate contains a mixture of ingredients of concentrated electrolytes and water in the 1–34 ratio. Condensed liquid would be commercially produced in the same quality and controlled conditions; but, the used water may have different qualities. In the case of using ordinary tap water, it is possible for potentially toxic substances to be transmitted from the dialysate to the patients' blood; hence, the water quality used to prepare dialysate is extremely important. In general, there are pretreatment systems (mainly reverse osmosis [RO]) before the dialysis instrument, which provide high water quality in accordance with the relevant standards. Many experts believe that some unfortunate incidents in the dialysis centers can be attributed to the dysfunction of pretreatment systems and the resulting poor feed water quality of the dialysis instrument. Minimal concentration of trace elements such as heavy metals in dialysate can significantly disturb the concentration of trace elements in the dialysis patients. Therefore, it is particularly important to consider elements such as aluminum, nickel, cadmium, lead, and chromium. For instance, the increase of nickel level can cause acute nickel toxicity. Furthermore, aluminum not only creates acute toxicity in dialysis patients, in a long run, but also causes brain and bone diseases through the disturbed balance of calcium phosphate. Based on the foregoing, it is very important to reduce the level of heavy metals in the water used in the dialysis instrument of HD patients. For alleviating the concerns about water used in HD patients, manufacturers of dialysis instruments have embedded the RO membrane in the dialysis instrument. Improper operation and maintenance of dialysis instruments and RO membrane decrease their efficiency in terms of removing water contaminants, which would jeopardize the health of HD patients in other aspects. Asadi et al. reported that the mean lead and cadmium levels were less than standard of the Association for the Advancement of Medical Instrumentation (AAMI) in the feed water of the dialysis instruments at hospitals of Qom. In another research conducted by Marjani and Vaghari  in Gorgan Medical Educational Center, it was revealed that the aluminum level in the feed water of the dialysis instrument exceeded the standard. Furthermore, Arvanitidou et al. stated that nickel, iron, and aluminum levels were higher than the standard in feed water of the 85 dialysis instrument centers in Greece.
The aim of the current study was to evaluate the concentration changes of heavy metals (lead, cadmium, chromium, and zinc) in used water at different stages of seven dialysis instruments and determine the role of RO membrane in the mentioned changes.
| Materials and Methods|| |
This work was a descriptive analytical study that was conducted in winter 2016. First, seven hospitals, including Imam Reza (Kermanshah), Hazrat Rasool (Javanrood), Shohada (Harsin), Moaven–ol-Malek (Sahneh), Imam Khomeini (Sonqor), Dr. Chamran (Kengavar), Imam Khomeini (Kermanshah), and Qodes (Paveh), which had dialysis instruments for HD patients, were selected in Kermanshah Province. For the sampling, 2 samples of feed water of the RO system (raw water), 2 samples of permeated water of the RO (feed water of the dialysis instrument), and 2 samples of condensed permeated water of the dialysis instrument were collected on two different days. In order for the samples to represent actual samples from the feed water of dialysis instrument, sampling days were randomly selected without prior arrangement with the hospitals. According to the repeated three times of experiments, in total, 126 samples (stored in 2-L plastic containers) of lead, cadmium, chromium, and zinc were measured using inductively coupled plasma (ICP) system (model DV-Optima 2100). Given that the samples were collected from the outlet of the RO system, it was not required to prepare the samples for injection into ICP. According to the Instructions of Standard Methods for the Examination of Water and Wastewater to save the samples, 5 ml of concentrated nitric acid was added and the pH value was reduced to <2. It should be noted that the pressure of RO (constructed of polyamide) used for water purification in the dialysis instrument at all the hospitals was between 200 and 250 patient safety indicators. To comply with the research ethics, the names of the hospitals and parameters were remained confidential.
To compare the mean concentrations measured by standard the AAMI, one-sample t-test at the significance level of α = 0.05 was used and role of the RO system in decreasing heavy metals was studied using paired t-test in SPSS software (version 16, SPSS Inc., Chicago, Delaware).
| Results|| |
Results showed that the mean concentration of each of the considered metals with a significant difference was less than the standard announced by the AAMI (P < 0.05) [Table 1]. In terms of the performance of RO system, results of the statistical paired t-test indicated that the RO system not only failed to reduce the concentration of lead and cadmium (P > 0.05) but also slightly increased the level of these two metals in the permeated water of RO system. However, this issue was reversed in the case of chromium and zinc (P < 0.05) [Table 2] and [Table 3]. [Figure 1],[Figure 2],[Figure 3],[Figure 4] show the trend changes of the considered metals in feed water of RO system and feed and permeated water of the dialysis instrument. Efficiency of RO membrane before the dialysis instrument in the removal of zinc and chromium was 61.5 and 2.1%, respectively; however, this system was not effective in terms of removing lead and cadmium metals [Figure 5].
|Table 1: Descriptive statistical parameters of the considered heavy metals in the raw feed water in reverse osmosis systems of the dialysis instruments at the hospitals of Kermanshah Province|
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|Table 2: Descriptive statistical parameters of the considered metals in the permeated water of reverse osmosis (feed water of the dialysis instrument) at hospitals of Kermanshah Province|
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|Table 3: Descriptive statistical parameters of the considered metals in the permeated water of the dialysis instrument of hospitals of Kermanshah Province|
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|Figure 1: Trend zinc in the water entering the reverse osmosis and inlet and outlet water of the dialysis systems. F.W of RO = Feed Water of Reverse Osmosis, P.W of RO = Permeated Water of Reverse Osmosis, P.W of RO = Permeated Water of Dialysis Instrument|
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|Figure 2: Trend cadmium in the water entering the reverse osmosis and inlet and outlet water of the dialysis system|
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|Figure 3: Trend of chromium in the water entering the reverse osmosis and inlet and outlet water of the dialysis systems|
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|Figure 4: Trend of lead in the water entering the reverse osmosis and inlet and outlet water of the dialysis systems|
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|Figure 5: Performance average of reverse osmosis membrane of studied dialysis systems in removal of heavy metals|
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| Discussion|| |
Results showed that the concentrations of each of the considered metals in the three types of samples (feed water of RO, permeated water of RO [feed water of the dialysis instrument], and permeated water of electrodialysis) had different trends. Lead and cadmium concentrations increased and chromium concentration was not significantly reduced after the reverse osmosis system (about 2.1% removal).
The first reason may be that after sometime, metals would be gradually accumulated on semipermeable membrane pore system because of concentration gradient and osmotic pressure. Furthermore, when raw water is pumped toward the membrane, metals may be moved to another side of the membrane. As a result, accumulated metals may be added to the permeated water of RO system,, which may indicate that the membrane is durable and the number of dialysis and volume of water passing through the device increase over time and result in the replacement requirement of the membrane system. The second possible reason could be related to the RO system's dialysis instruments which have nonselective membranes and high efficiency in removing the dissolved minerals. As a result, water pH tends to acidification, which would be effective in the corrosion of metal equipment such as pipes transmitting water to HD instrument. If these equipment have high impurity metal alloys, some metals may be added to the used water., The study by Baseri et al. indicated that the mean pH of feed water to the RO system of dialysis instrument was decreased from 7.6 ± 0.24–6.78 ± 0.19. Alizadeh et al. showed that the pH of permeated water of the RO system toward the feed water of dialysis instrument was decreased at the hospitals of Zahedan University of Medical Sciences. Asadzadeh et al. reported that pH of the permeated water of the RO system of dialysis instrument at Bahman Hospital of Gonabad decreased to 5.1.
Based on the results and the above-mentioned problems associated with the membrane of RO systems, chromium and lead concentrations of the feed water into the dialysis instrument were significantly higher than the maximum allowable of the AAMI standard (P < 0.05). Considering the importance of these two metals in terms of health (particularly, for HD patients), it is essential to take necessary measures for cleaning or replacing the RO membrane systems of dialysis instruments.
In this regard, results of the present work were in line with those of some previous studies and did not match some others.
In the study by Sandgol et al. in Khatam-al-Anbia Hospital and Marjani and Vaghari's  work in Educational and Therapeutic Center of Panjom–e–Azar in Gorgan, the aluminum level in the feed water of dialysis instruments was higher than the standard while in this study, all of the considered metals were significantly less than the standard. Arvanitidou et al. stated that the level of nickel, iron, and aluminum in the feed water of the dialysis instruments of 85 health centers of Greece was higher than the standard. Furthermore, the study that was conducted on 30 elements in Mexico by Sobrino et al. showed that among the considered elements, only aluminum was higher than AAMI standard while this issue was the opposite in the current study.
However, the study by Asadi et al. indicated that mean lead and cadmium levels in the feed water of dialysis instruments at hospitals of Qom were less than the AAMI standard. Furthermore, the study by Baseri et al. showed that the quality of feed water of dialysis instruments of a hospital in Kashan was in accordance with the standard in terms of lead, cadmium, chromium, and copper, which was similar to the present study.
Results also indicated that lead and chromium concentrations were increased in the permeated water of dialysis instrument, which may be due to higher concentration of the considered metals in the feed water of dialysis instrument than the one in blood of HD patients. Therefore, the metals transmitted from feed water to blood and the resulting levels were decreased in the condensed water (feed water of dialysis instrument). Hence, prevention from the increased level of heavy metals (more than the AAMI standard) in feed water of dialysis instrument can prevent its transfer to blood.
| Conclusions|| |
Increasing lead and cadmium levels in the permeated water of RO system compared to the raw water inlet indicates the performance loss of RO system and that the polyamide membrane of RO system should be periodically washed or replaced. Feed water quality of all the dialysis instruments at the hospitals of Kermanshah Province in terms of cadmium and zinc was in accordance with the AAMI and EPA standards; however, this issue was the opposite in terms of lead and chromium metals. Reduction of lead and chromium levels in the permeated water of dialysis instrument indicated the addition of two mentioned dangerous metals to the blood of HD patients, which could be associated with the fault of RO membrane and high level of the mentioned metals in its permeated water. Hence, monthly monitoring of the performance of HD instruments in terms of the water quality produced by RO (especially, in terms of heavy metals) by the operators is recommended for proper operation and maintenance of high performance of HD instruments. Improper monitoring of all the HD instruments at hospitals of Kermanshah Province and deficient investigation of their function and membrane lifetime (due to the lack of access to them through the supervisors of dialysis part and low knowledge of the instrument operators) were among the limitation of this study.
This study is the result from Master's thesis (Shahram Naderi). Authors warmly appreciate the efforts of Kermanshah Province's hospitals' managements and laboratory supervisors of Azad University of Kermanshah for their cooperation in this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]
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