Tag Archives: aluminum

Mn and Al deposits in drinking water distribution systems

Li G, Ding Y, Xu H, Jin J, Shi B. Characterization and release profile of (Mn, Al)-bearing deposits in drinking water distribution systems. Chemosphere. 2018 Jan 9;197:73-80. doi: 10.1016/j.chemosphere.2018.01.027.

Inorganic contaminants accumulation in drinking water distribution systems (DWDS) is a great threat to 2 without well crystalline form. The relative abundance of Mn and Fe in deposits changed with their distance from the water treatment plant. Compared with iron in corrosion scales, Mn and Al were more labile to be released back into bulk water during unidirectional flushing process. A main finding of this work is the co-release behavior of Mn and Al in particulate form and significant correlation exists between these two metals. Dual control of manganese and aluminum in treated water is proposed to be essential to cope with discoloration and trace metal contamination in DWDS.

Allowable Concentrations of Aluminum in Drinking Water

Willhite CC, Ball GL, McLellan CJ. Total allowable concentrations of monomeric inorganic aluminum and hydrated aluminum silicates in drinking water. Critical reviews in toxicology. 2012 May;42(5):358-442. doi: 10.3109/10408444.2012.674101.

Maximum contaminant levels are used to control potential health hazards posed by chemicals in drinking water, but no primary national or international limits for aluminum (Al) have been adopted. Given the differences in toxicological profiles, the present evaluation derives total allowable concentrations for certain water-soluble inorganic Al compounds (including chloride, hydroxide, oxide, phosphate and sulfate) and for the hydrated Al silicates (including attapulgite, bentonite/montmorillonite, illite, kaolinite) in drinking water. The chemistry, toxicology and clinical experience with Al materials are extensive and depend upon the particular physical and chemical form. In general, the water solubility of the monomeric Al materials depends on pH and their water solubility and gastrointestinal bioavailability are much greater than that of the hydrated Al silicates. Other than Al-containing antacids and buffered aspirin, food is the primary source of Al exposure for most healthy people. Systemic uptake of Al after ingestion of the monomeric salts is somewhat greater from drinking water (0.28%) than from food (0.1%). Once absorbed, Al accumulates in bone, brain, liver and kidney, with bone as the major site for Al deposition in humans. Oral Al hydroxide is used routinely to bind phosphate salts in the gut to control hyperphosphatemia in people with compromised renal function. Signs of chronic Al toxicity in the musculoskeletal system include a vitamin D-resistant osteomalacia (deranged membranous bone formation characterized by accumulation of the osteoid matrix and reduced mineralization, reduced numbers of osteoblasts and osteoclasts, decreased lamellar and osteoid bands with elevated Al concentrations) presenting as bone pain and proximal myopathy. Aluminum-induced bone disease can progress to stress fractures of the ribs, femur, vertebrae, humerus and metatarsals. Serum Al ≥100 µg/L has a 75-88% positive predictive value for Al bone disease. Chronic Al toxicity is also manifest in the hematopoietic system as an erythropoietin-resistant microcytic hypochromic anemia. Signs of Al toxicity in the central nervous system (speech difficulty to total mutism to facial grimacing to multifacial seizures and dyspraxia) are related to Al accumulation in the brain and these symptoms can progress to frank encephalopathy. There are four groups of people at elevated risk of systemic Al intoxication after repeated ingestion of monomeric Al salts: the preterm infant, the infant with congenital uremia and children and adults with kidney disease. There is a dose-dependent increase in serum and urinary Al in people with compromised renal function, and restoration of renal function permits normal handling of systemically absorbed Al and resolution of Al bone disease. Clinical experience with 960 mg/day of Al(OH)(3) (~5 mg Al/kg-day) given by mouth over 3 months to men and women with compromised renal function found subclinical reductions in hemoglobin, hematocrit and serum ferritin. Following adult males and females with reduced kidney function found that ingestion of Al(OH)(3) at 2.85 g/day (~40 mg/kg-day Al) over 7 years increased bone Al, but failed to elicit significant bone toxicity. There was one report of DNA damage in cultured lymphocytes after high AlCl(3) exposure, but there is no evidence that ingestion of common inorganic Al compounds presents an increased carcinogenic risk or increases the risk for adverse reproductive or developmental outcomes. A number of studies of Al exposure in relation to memory in rodents have been published, but the results are inconsistent. At present, there is no evidence to substantiate the hypothesis that the pathogenesis of Alzheimer’s Disease is caused by Al found in food and drinking water at the levels consumed by people living in North America and Western Europe. Attapulgite (palygorskite) has been used for decades at oral doses (recommended not to exceed two consecutive days) of 2,100 mg/day in children of 3-6 years, 4,200 mg/day in children of 6-12 years, and 9,000 mg/day in adults. Chronic ingestion of insoluble hydrated Al silicates (in kg) can result in disturbances in iron and potassium status, primarily as a result of clay binding to intestinal contents and enhanced fecal iron and zinc elimination. Sufficiently high doses of ingested Al silicates (≥50 g/day) over prolonged periods of time can elicit a deficiency anemia that can be corrected with oral Fe supplements. There is essentially no systemic Al uptake after ingestion of the hydrated Al silicates. Rats fed up to 20,000 ppm Ca montmorillonite (equivalent to 1,860 ppm total Al as the hydrated Al silicate) for 28 weeks failed to develop any adverse signs. The results of dietary Phase I and II clinical trials conducted in healthy adult volunteers over 14 days and 90 days with montmorillonite found no adverse effects after feeding up to 40 mg/kg-day as Al. Since the Al associated with ingestion of hydrated Al silicates is not absorbed into the systemic circulation, the hydrated Al silicates seldom cause medical problems unless the daily doses consumed are substantially greater than those used clinically or as dietary supplements. A no-observable-adverse-effect-level (NOAEL) of 13 mg/kg-day as total Al can be identified based on histologic osteomalacia seen in adult hemodialysis patients given Al hydroxide for up to 7 years as a phosphate binder. Following U.S. EPA methods for calculation of an oral reference dose (RfD), an intraspecies uncertainty factor of 10x was applied to that value results in a chronic oral reference dose (RfD) of 1.3 mg Al/kg-day; assuming a 70-kg adult consumes 2 L of drinking water per day and adjusting for a default 20% relative source contribution that value corresponds to a drinking water maximum concentration of 9 mg/L measured as total Al. A chronic NOAEL for montmorillonite as representative of the hydrated Al silicates was identified from the highest dietary concentration (20,000 ppm) fed in a 28-week bioassay with male and female Sprague-Dawley rats. Since young rats consume standard laboratory chow at ~23 g/day, this concentration corresponds to 56 mg Al/kg-day. Application of 3x interspecies uncertainty factor and a 3x factor to account for study duration results in a chronic oral RfD of 6 mg Al/kg-day. Of note, this RfD is 5-10 fold less than oral doses of Al silicates consumed by people who practice clay geophagy and it corresponds to a maximum drinking water concentration of 40 mg Al/L. To utilize the values derived here, the risk manager must recognize the particular product (e.g., alum) or source (e.g., groundwater, river water, clay or cement pipe) of the Al found in tap water, apply the appropriate analytical methods (atomic absorption, energy dispersive X-ray diffraction, infrared spectral analysis and/or scanning transmission electron microscopy) and compare the results to the most relevant standard. The drinking water concentrations derived here are greater than the U.S. EPA secondary maximum contaminant level (MCL) for total Al of 0.05-0.2 mg/L [40 CFR 143.3]. As such, domestic use of water with these concentrations is likely self-limiting given that its cloudy appearance will be greater than the maximum permitted (0.5-5.0 nephalometric turbidity units; 40 CFR Parts 141 and 142). Therefore, the organoleptic properties of Al materials in water determine public acceptance of potable water as contrast to any potential health hazard at the concentrations ordinarily present in municipal drinking water.

Aluminum and Silicon in Drinking Water, Isfahan, Iran

Pourgheysari H, Hajizadeh Y, Tarrahi MJ, Ebrahimi A. Association between Aluminum and Silicon Concentrations in Isfahan Drinking Water and Their Health Risk Assessments. International Journal of Preventive Medicine. 2015 Nov 12;6:111. doi: 10.4103/2008-7802.169644.

BACKGROUND: High concentrations of elements such as aluminum (Al) and silicon (Si) in drinking water can affect human health. It is suggested that high daily intake of Al is associated with increased risk of neurodegenerative disorders. Si, as an antidote of Al, may decrease Al bioavailability. The study was conducted to estimate Al and Si concentration and correlation in water and evaluate their health risk.

METHODS: In this cross-sectional study, water samples were collected from 20 points of water distribution system and the water treatment plant of Isfahan in spring and summer. Samples were analyzed using DR-5000. The health risk was evaluated via calculating chronic daily intake (CDI) and hazard index (HI).

RESULTS: Significant negative correlation was documented between Al and Si (R = -0.482, P = 0.037 in spring, and R = -0.452, P = 0.049 in summer). These values were approximately similar in all types of Al and Si. The amounts of CDI for Al in spring and summer were 6.67E-04 and 0.002 mg/kg/day, respectively. The Al HI values were below 1 in both seasons.

CONCLUSIONS: The significant correlation between Al and Si concentrations suggests that Si can eliminate Al in water, and probably it might do the same in the body. The health risk of Al intake from tap water was negligible, it was assessed in an acceptable range with an HI value of less than the standard levels. The health risk of Si remained unknown due to lack of information regarding its toxicity and adverse health effects.

Citrate Solubilizes Aluminum Present in Food, Drinking Water

The bioavailability of aluminum alone is very low. That citrate increases the bioavailability of ingested aluminum has been know for many years. People with chronic kidney disease must pay attention to this to avoid an overexposure to aluminum.

Ajay Gupta. Ferric Citrate Hydrate as a Phosphate Binder and Risk of Aluminum Toxicity. Pharmaceuticals. Oct2014, Vol. 7 Issue 10, p990-998.

Ferric citrate hydrate was recently approved in Japan as an oral phosphate binder to be taken with food for the control of hyperphosphatemia in patients with chronic kidney disease (CKD). The daily therapeutic dose is about 3 to 6 g, which comprises about 2 to 4 g of citrate. Oral citrate solubilizes aluminum that is present in food and drinking water, and opens the tight junctions in the intestinal epithelium, thereby increasing aluminum absorption and urinary excretion. In healthy animals drinking tap water, oral citrate administration increased aluminum absorption and, over a 4-week period, increased aluminum deposition in brain and bone by about 2- and 20-fold, respectively. Renal excretion of aluminum is impaired in patients with chronic kidney disease, thereby increasing the risk of toxicity. Based on human and animal studies it can be surmised that patients with CKD who are treated with ferric citrate hydrate to control hyperphosphatemia are likely to experience enhanced absorption of aluminum from food and drinking water, thereby increasing the risk of aluminum overload and toxicity.

Alum Sludge on Vegetative Buffer Strips Reduced Phosphorus in Surface Runoff

Habibiandehkordi R, Quinton JN, Surridge BW. Long-term effects of drinking-water treatment residuals on dissolved phosphorus export from vegetated buffer strips. Environmental science and pollution research international. 2014 Nov 13.

The export of dissolved phosphorus (P) in surface runoff from agricultural land can lead to water quality degradation. Surface application of aluminium (Al)-based water treatment residuals (Al-WTRs) to vegetated buffer strip (VBS) soils can enhance P removal from surface runoff during single runoff events. However, the longer-term effects on P removal in VBSs following application of products such as Al-WTR remain uncertain. We used field experimental plots to examine the long-term effects of applying a freshly generated Al-WTR to VBSs on dissolved P export during multiple runoff events, occurring between 1 day and 42 weeks after the application of Al-WTR. Vegetated buffer strip plots amended with Al-WTR significantly reduced soluble reactive P and total dissolved P concentrations in surface runoff compared to both unamended VBS plots and control plots. However, the effectiveness of Al-WTR decreased over time, by approximately 70 % after 42 weeks compared to a day following Al-WTR application. Reduced performance did not appear to be due to drying of Al-WTR in the field. Instead, the development of preferential flow paths as well as burying of Al-WTR with freshly deposited sediments may explain these observations. Better understanding of the processes controlling long-term P removal by Al-WTR is required for effective management of VBSs.

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Allowable concentration of aluminum in drinking water derived….

No primary drinking water standard for aluminum exists……this paper derives total allowable concentrations for certain water-soluble inorganic Al compounds…..Using USEPA risk assessment approach, a drinking water maximum concentration of 9 mg/L measured as total Al is derived…..

Whillhite, CC, BAll, GL, and CJ McLellan. Total allowable concentrations of monomeric inorganic aluminum and hydrated aluminum silicates in drinking water. Crit Rev Toxicol. 2012 May;42(5):358-442.

Abstarct: Maximum contaminant levels are used to control potential health hazards posed by chemicals in drinking water, but no primary national or international limits for aluminum (Al) have been adopted. Given the differences in toxicological profiles, the present evaluation derives total allowable concentrations for certain water-soluble inorganic Al compounds (including chloride, hydroxide, oxide, phosphate and sulfate) and for the hydrated Al silicates (including attapulgite, bentonite/montmorillonite, illite, kaolinite) in drinking water. The chemistry, toxicology and clinical experience with Al materials are extensive and depend upon the particular physical and chemical form. In general, the water solubility of the monomeric Al materials depends on pH and their water solubility and gastrointestinal bioavailability are much greater than that of the hydrated Al silicates. Other than Al-containing antacids and buffered aspirin, food is the primary source of Al exposure for most healthy people.

Systemic uptake of Al after ingestion of the monomeric salts is somewhat greater from drinking water (0.28%) than from food (0.1%). Once absorbed, Al accumulates in bone, brain, liver and kidney, with bone as the major site for Al deposition in humans. Oral Al hydroxide is used routinely to bind phosphate salts in the gut to control hyperphosphatemia in people with compromised renal function. Signs of chronic Al toxicity in the musculoskeletal system include a vitamin D-resistant osteomalacia (deranged membranous bone formation characterized by accumulation of the osteoid matrix and reduced mineralization, reduced numbers of osteoblasts and osteoclasts, decreased lamellar and osteoid bands with elevated Al concentrations) presenting as bone pain and proximal myopathy. Aluminum-induced bone disease can progress to stress fractures of the ribs, femur, vertebrae, humerus and metatarsals. Serum Al ≥100 µg/L has a 75-88% positive predictive value for Al bone disease. Chronic Al toxicity is also manifest in the hematopoietic system as an erythropoietin-resistant microcytic hypochromic anemia.

Signs of Al toxicity in the central nervous system (speech difficulty to total mutism to facial grimacing to multifacial seizures and dyspraxia) are related to Al accumulation in the brain and these symptoms can progress to frank encephalopathy. There are four groups of people at elevated risk of systemic Al intoxication after repeated ingestion of monomeric Al salts: the preterm infant, the infant with congenital uremia and children and adults with kidney disease. There is a dose-dependent increase in serum and urinary Al in people with compromised renal function, and restoration of renal function permits normal handling of systemically absorbed Al and resolution of Al bone disease. Clinical experience with 960 mg/day of Al(OH)(3) (~5 mg Al/kg-day) given by mouth over 3 months to men and women with compromised renal function found subclinical reductions in hemoglobin, hematocrit and serum ferritin. Following adult males and females with reduced kidney function found that ingestion of Al(OH)(3) at 2.85 g/day (~40 mg/kg-day Al) over 7 years increased bone Al, but failed to elicit significant bone toxicity. There was one report of DNA damage in cultured lymphocytes after high AlCl(3) exposure, but there is no evidence that ingestion of common inorganic Al compounds presents an increased carcinogenic risk or increases the risk for adverse reproductive or developmental outcomes.

A number of studies of Al exposure in relation to memory in rodents have been published, but the results are inconsistent. At present, there is no evidence to substantiate the hypothesis that the pathogenesis of Alzheimer’s Disease is caused by Al found in food and drinking water at the levels consumed by people living in North America and Western Europe. Attapulgite (palygorskite) has been used for decades at oral doses (recommended not to exceed two consecutive days) of 2,100 mg/day in children of 3-6 years, 4,200 mg/day in children of 6-12 years, and 9,000 mg/day in adults.

Chronic ingestion of insoluble hydrated Al silicates (in kg) can result in disturbances in iron and potassium status, primarily as a result of clay binding to intestinal contents and enhanced fecal iron and zinc elimination. Sufficiently high doses of ingested Al silicates (≥50 g/day) over prolonged periods of time can elicit a deficiency anemia that can be corrected with oral Fe supplements. There is essentially no systemic Al uptake after ingestion of the hydrated Al silicates. Rats fed up to 20,000 ppm Ca montmorillonite (equivalent to 1,860 ppm total Al as the hydrated Al silicate) for 28 weeks failed to develop any adverse signs. The results of dietary Phase I and II clinical trials conducted in healthy adult volunteers over 14 days and 90 days with montmorillonite found no adverse effects after feeding up to 40 mg/kg-day as Al. Since the Al associated with ingestion of hydrated Al silicates is not absorbed into the systemic circulation, the hydrated Al silicates seldom cause medical problems unless the daily doses consumed are substantially greater than those used clinically or as dietary supplements.

A no-observable-adverse-effect-level (NOAEL) of 13 mg/kg-day as total Al can be identified based on histologic osteomalacia seen in adult hemodialysis patients given Al hydroxide for up to 7 years as a phosphate binder. Following U.S. EPA methods for calculation of an oral reference dose (RfD), an intraspecies uncertainty factor of 10x was applied to that value results in a chronic oral reference dose (RfD) of 1.3 mg Al/kg-day; assuming a 70-kg adult consumes 2 L of drinking water per day and adjusting for a default 20% relative source contribution that value corresponds to a drinking water maximum concentration of 9 mg/L measured as total Al. A chronic NOAEL for montmorillonite as representative of the hydrated Al silicates was identified from the highest dietary concentration (20,000 ppm) fed in a 28-week bioassay with male and female Sprague-Dawley rats. Since young rats consume standard laboratory chow at ~23 g/day, this concentration corresponds to 56 mg Al/kg-day. Application of 3x interspecies uncertainty factor and a 3x factor to account for study duration results in a chronic oral RfD of 6 mg Al/kg-day. Of note, this RfD is 5-10 fold less than oral doses of Al silicates consumed by people who practice clay geophagy and it corresponds to a maximum drinking water concentration of 40 mg Al/L.

To utilize the values derived here, the risk manager must recognize the particular product (e.g., alum) or source (e.g., groundwater, river water, clay or cement pipe) of the Al found in tap water, apply the appropriate analytical methods (atomic absorption, energy dispersive X-ray diffraction, infrared spectral analysis and/or scanning transmission electron microscopy) and compare the results to the most relevant standard. The drinking water concentrations derived here are greater than the U.S. EPA secondary maximum contaminant level (MCL) for total Al of 0.05-0.2 mg/L [40 CFR 143.3]. As such, domestic use of water with these concentrations is likely self-limiting given that its cloudy appearance will be greater than the maximum permitted (0.5-5.0 nephalometric turbidity units; 40 CFR Parts 141 and 142). Therefore, the organoleptic properties of Al materials in water determine public acceptance of potable water as contrast to any potential health hazard at the concentrations ordinarily present in municipal drinking water.

Click here for full paper (fee).

Wang et al 2011: Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification

W. Wang, H. Li, Z. Ding, and X. Wang. Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification. J Environ Sci (China). 2011;23(7):1079-85.

School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China. wwd@xauat.edu.cn

Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O3/mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al(OH)3(s). This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.