Drinking Water Quality and Contaminants Guidebook

Joseph Cotruvo

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9780815363057
• eBook ISBN: 9781351110457
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

K347191 BCC

Drinking water quality is a sensitive issue, and the public is constantly barraged by contaminant reports now routinely at parts-per-trillion. Protection from microbial disease risks from drinking water must always be predominant; trace chemicals usually fall farther down the scale of possible health risks, but even negligible detections raise public concerns.

Drinking Water Quality and Contaminants Guidebook presents information and guidance on drinking water quality and regulatory issues reflecting experiences and judgments from the author's more than 43 years of extensive experience. It contains digested comprehensive information on important chemical, microbial, and radionuclide water contaminants, and discussions of several drinking water-related policy issues. Information is presented for long-standing regulated contaminants and chemicals of emerging concern in understandable terms for professionals and non-experts alike. Dossiers contain readily accessed information on sources, physical and chemical properties, toxicity, analytical methodology, water treatment technology, regulations and health advisories, and also include World Health Organization Guidelines. Aesthetic and acceptance factors such as water hardness and salinity that influence public perceptions of drinking water quality are also addressed.

Features:

• Compiles and interprets essential information on numerous key chemical, microbial, and radionuclide water contaminants
• Provides standardized entries for each contaminant, including occurrence, health, analytical, water treatment, regulations, and World Health Organization guidance and recommendations with source citations
• Examines many water-related topics including fracking, potable water reuse, desalination, boil water notices, bottled water, foodborne and waterborne disease, and public perceptions about public drinking water quality
• Provides essential information and the basis for management of many long-standing contaminants such as lead, mercury, disinfection by-products, E. coli, and also emerging issues such as legionella, glyphosate, BPA, and more

1 Inorganic Chemicals in Drinking Water

ARSENIC

INTRODUCTION

Arsenic is element 33 in the periodic table with an atomic weight of 75 Da. Natural arsenic is the stable isotope that contains 33 protons and 42 neutrons. Arsenic was formerly used in wood preservatives. Paris Green, perhaps the first commercial pesticide, is a copper arsenite and copper acetate complex originally prepared in 1814 and used as a general insecticide and rodenticide. Many years ago, there were unproven medical uses for arsenic, but one of the visible outcomes was a horny skin keratosis, as well as other toxicity consequences.

PHYSICAL AND CHEMICAL PROPERTIES

Arsenic is a metalloid, neither a metal nor a nonmetal. Arsenic is found in oxidation states of −3 (arsenides), 0 (elemental arsenic), +3 (arsenite and arsenic trichloride), and +5 (arsenate) so it can exist in many inorganic and also organic compounds (e.g., methylarsonic acid and its salts).

OCCURRENCE

Arsenic is widely distributed in the earth’s crust. It is found in groundwaters as arsenite (AsO₃⁻³) or arsenate (AsO₄⁻³) salts. World water concentrations range from less than 1 µg/L to multiple mg/L amounts. The median level in US drinking water in some studies was 1.5 µg/L, and the 95th percentile was 15.4 µg/L. The 1988 National Inorganics and Radionuclides Survey study of 982 groundwater supplies found 6.52 percent positives above 5 µg/L. The mean of the positives was 13 µg/L, and two exceeded 40 µg/L. There are pockets of high arsenic levels in groundwaters in the northeast and western United States as well as other locations.

Arsenic is found in foods, with fish and shellfish being by far the largest contributors to daily diet. About 99 percent of the seafood arsenic is in organic forms that are likely much less toxic than the inorganic forms.

It is common in cereals, poultry, grains, and vegetables with only trace amounts in milk. Rice can contain on the order of 6.7 µg of inorganic arsenic per cup depending upon where it was grown. Rice is grown in water so it has a greater opportunity to accumulate arsenic from the environment. In the cited Food and Drug Administration (FDA) total diet study, daily intakes ranged from 2 µg/day for infants, 23 µg/day for toddlers, up to a high of 92 µg/day for 60- to 65-year-old men, and 72 µg/day for 60- to 65-year-old women. Seafood contributed 76 to 90 percent for children (2- to 10-year-olds), 79 to 85 percent for 14- to 16-year-olds, and 89 to 96 percent for adults (≥25- to 30-year-olds); rice/rice cereals contributed 4 to 8 percent for children, 8 percent for 14- to 16-year-olds, and 1 to 4 percent for adults (≥25- to 30-year-olds).

HEALTH EFFECTS

Arsenic is acutely toxic at high doses, but it also has chronic toxicity at lower doses and it is a human carcinogen. Inorganic arsenic compounds (arsenate and arsenite) pose greater risks than the organic forms that predominate in the diet.

Skin, bladder, and lung cancer, as well as keratosis have been identified from exposures to inorganic arsenic at high, hundreds of µg/L, water and dietary exposure levels, e.g., Bangladesh and Taiwan.

In Bangladesh, for many years the World Health Organization (WHO) and others had provided thousands of drinking water wells so that microbiologically contaminated surface waters would not be used. However, unfortunately, it was later discovered that many of the wells were heavily contaminated with natural arsenic sometimes in hundreds of µg/L, resulting in high incidences of cancers in the exposed populations.

A 2013 study found no correlations between total arsenic and inorganic arsenic and total cancer risks in Japan. There was a small correlation between total and inorganic arsenic dietary intake and lung cancer with male smokers. Some studies suggest a possibility of lower birth weights at arsenic concentrations in drinking water, somewhat less than 50 µg/L. A US study of male bladder cancer mortality in 133 counties exclusively using groundwater between 1950 and 1979 found no arsenic-related cancer connection over the range of 3–60 µg/L in the drinking water.

ANALYSIS

Commonly available methods for analyzing arsenic in water include inductively coupled plasma mass spectrometry (ICP-MS; detection limit ~0.1 µg/L) (Environmental Protection Agency [EPA] method 200.8). The older hydride generation atomic absorption and flame atomic absorption (detection limits ~ 1–2 µg/L) have been deleted. The standard methods technique is 3500-As.

There are numerous easy-to-use test kits that allow quick on-site colorimetric measurements that can readily detect amounts below 5 µg/L.

They are particularly useful as a presence–absence test for screening and when monitoring the performance of treatment technology.

WATER TREATMENT

Conventional coagulation can achieve less than 10 µg/L in public water plants using either alum or ferric salts. Co-precipitation with iron or aluminum oxides is also effective. Reverse osmosis (RO) (arsenate > arsenite) and anion exchange processes using iron-based products and activated alumina are very effective. Water softening is effective by sorption if magnesium or iron precipitation occurs, but not with calcite alone.

Point-of-use (POU) technologies are particularly cost-effective in home water well or managed small community-wide water supply applications. Anion exchange, RO, and distillation are available for POU/point-of-entry (POE) applications. POU will be most cost-effective because only a few liters of water will be needed each day for drinking and cooking. Community-supplied bottled water is also a viable approach.

A detailed study of a community-wide POU-decentralized treatment for arsenic removal has demonstrated the methodology and success of the concept.

REGULATIONS

Arsenic had been regulated in the United States at 50 µg/L. This standard was lowered to 10 µg/L in 2001. The predominant impact of the standard has been in 3,000–4,000 small groundwater supplies serving about 11,000,000 people that exceed the maximum contaminant level (MCL). All arsenic pesticide registrations in the United States either have been or are being cancelled. The WHO drinking water guideline is also 10 µg/L. California’s public health goal (PHG) is 0.004 µg/L for arsenic in drinking water based on their negligible risk (1/1,000,000) estimate for lifetime extra risk of skin and internal cancers, which seems to be unrealistic. Its MCL is also 10 µg/L. By that logic, the risk at the MCL would be 2,500/million, or 2.5/1,000.

CONCLUSION

It is possible that the current California’s PHG and the EPA MCL and WHO Guidelines for Drinking Water Quality (GDWQ) are unnecessarily conservative. The burden for arsenic treatment is significant in some small groundwater systems in the United States that are the most likely exceeders. Centrally managed (by contract) decentralized POU systems might be the most appropriate technical and economic compliance choice, or even community-supplied bottled water for the small-volume drinking water and cooking uses because of the small volumes required.

SOURCES

California (2004). Public Health Goals For Chemicals in Drinking Water Arsenic. www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/california_waterfix/exhibits/docs/SHR/SHR-25.pdf.

Cotruvo JA (2013). Arsenic. Contaminant of the Month. Water Technology on Line. www.watertechonline.com/contaminant-of-the-month-arsenic/September, 2013.

EPA (2001). Fact Sheet: Drinking Water Standard for Arsenic. www.epa.gov/lawsregs/rulesregs/sdwa/arsenic/regulations_factsheet.cfm Updated 2012. Accessed February 24, 2018.

EPA (2013). Organic Arsenicals. www.epa.gov/oppsrrd1/reregistration/organic_arsenicals_fs.html. Accessed February 24, 2018.

EPA (2017). Drinking Water Contaminants—Standards and Regulations. www.epa.gov/dwstandardsregulations accessed March 25, 2018.

EPA (2012). Drinking Water Health Advisories. www.epa.gov/sites/production/files/2015-09/documents/dwstandards2012.pdf.

EPA (1994). Method 200.8, Revision 5.4: Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma Mass Spectrometry. www.epa.gov/sites/production/files/2015-08/documents/method_200-8_rev_5-4_1994.pdf.

Feasibility of an Economically Sustainable Point-of-Use/Point-of-Entry Decentralized Public Water System. EPA Grant X82952301.

Hopenhayn C. et al (2003). Arsenic exposure from drinking water and birth weight. Epidemiology. 14(5): pp. 593–602.

Lamm SH, Engel A, Kruse MB, Feinleib M, Byrd DM, Lai S, Wilson R (2004). Arsenic in drinking water and bladder cancer mortality in the United States: An analysis based on 133 U.S. counties and 30 years of observation (1950–1979). Journal of Occupational and Environmental Medicine. 46(3): pp. 298–306.

Longtin JP (1988). EPA National Inorganics and Radionuclides Survey (NIRS).

Sawada N. et al (2013). Dietary arsenic intake and subsequent risk of cancer: The Japan Public Health Center-based Prospective Study. Cancer Causes Control. 24(7): pp. 1403–14115.

Standard Methods (2017). Standard Methods for the Examination of Water and Wastewater, 23rd Edition. www.techstreet.com/standards/standard-methods-for-the-examination-of-water-and-wastewater-23rd-edition?sid=msn&utm_medium=cpc&utm_source=bing&product_id=1974889.

Tao SH and Bolger PM (1999). Dietary arsenic intakes in the United States: FDA Total Diet Study, September 1991–December 1996. Food Additives & Contaminants. 16(11): pp. 465–472.

WHO (2017). World Health Organization Guidelines for Drinking-Water Quality. http://www.who.int/water_sanitation_health/publications/drinking-water-quality-guidelines-4-including-1st-addendum/en/.

BARIUM

INTRODUCTION

Barium is a soft metal with atomic number 56 and atomic weight 137.34 Da. It has some limited commercial uses in electronics and some alloys. It is reactive so it is never found in nature as a metal, but as salts. It provides the green color in firework displays, and insoluble barium sulfate is used as the contrast medium (barium enema) for gastrointestinal (GI) tract X-ray examinations.

PHYSICAL AND CHEMICAL PROPERTIES

Barium is an alkaline earth metal in the same category as magnesium, calcium, strontium, and radium, so it has very similar chemical properties. It forms Ba²⁺ salts with many anions, and many of the salts such as barium sulfate and barium carbonate have low water solubility. However, barium chloride is 37.4 percent water soluble at 25°C.

OCCURRENCE AND EXPOSURE

Barium salts have minimal substantial occurrence in surface waters in the United States and thus negligible exposure potential from surface drinking water supplies. Many groundwaters, e.g., hard waters in the Midwest, have detectable amounts of barium along with calcium and magnesium, and some strontium. However, the overall national occurrence significance in drinking water is small. The United States Geological Survey National Water Quality Assessment Program (USGS NAWQA) studies reported 99.8 percent detections in 523 surface waters, but none exceeded the EPA MCL goal (MCLG)/MCL of 2 mg/L. There were 99.6 percent detections in 6,934 groundwaters, but only 5 (0.1 percent) exceeded 2 mg/L and 1 exceeded 6 mg/L.

HUMAN HEALTH EFFECTS

Barium at sufficiently high exposures could affect blood pressure and therefore potentially cardiovascular disease risk. An epidemiology study found no significant differences in health effects while comparing a community with 7.3 mg/L and another with 0.1 mg/L in the drinking water. An EPA health effects assessment for barium considered relevant toxicity studies including developmental and reproductive toxicity, and it revised the reference dose (RfD) for barium from 0.07 to 0.2 mg/kg/day. The assessment also concluded that barium is not likely to be carcinogenic to humans. EPA also determined that the original 20 percent drinking water relative source contribution (RSC) should be raised to 80 percent which raised the drinking water equivalent level (DWEL) to 7 mg/L. The WHO calculated a tolerable daily intake (TDI; similar to an RfD) of 0.21 mg/kg bw/day, to a BMDL₀₅ (benchmark dose, 5 percent) of 63 mg/kg/day for nephropathy in mice in a 2-year study, with a 20 percent drinking water RSC and a safety factor of 300.

During the third Six-Year Review cycle, EPA did not identify any changes in health effects information. Therefore, the RfD of 0.2 mg/kg/day remains the appropriate basis for health protection.

ANALYTI...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Author
• List of Acronyms and Abbreviations
• Chapter 1 Inorganic Chemicals in Drinking Water
• Chapter 2 Organic Chemicals in Drinking Water
• Chapter 3 Selected Microbial Contaminants
• Chapter 4 Radioactivity in Drinking Water
• Chapter 5 Disinfection and Chlorine Disinfectants
• Chapter 6 Water Quality Parameters
• Chapter 7 Special Topics
• Index