The Politics of Regulation: Hexavalent Chromium and Arsenic

Hexavalent chromium, or Cr(VI), is almost constantly in the news lately. California’s Office of Environmental Health Hazard Assessment (OEHHA) has set a hotly contested Public Health Goal (PHG) of 0.020 ug/L, or 20 parts per trillion. Rep. Adam Schiff (D-CA) has introduced legislation into the U.S. House of Representatives to regulate Cr(VI), and Senator Barbara Boxer (D-CA) has introduced the companion legislation into the U.S. Senate. The U.S. Environmental Protection Agency (EPA) is re-reviewing the toxicological data for Cr(VI) after intense political and public pressure to regulate the chemical. But don’t confuse all of this frenzied activity with productivity, or even effective purpose.

The PHG setting process in California is a very rigorous one that takes into account the best available toxicological data in the scientific literature. OEHHA has identified the PHG level of 0.020 ug/L “as protective against all identified toxic effects from both oral and inhalation exposure to hexavalent chromium that may be present in drinking water.”(1) However, there is a great deal of debate among toxicologists that this PHG has been set much too low because of the methodology used in many of the studies OEHHA relied on. In contrast, there is almost no debate that almost any level of arsenic consumption can cause adverse health effects. The PHG in California has been set for arsenic at 0.004 ug/l, which is 4 parts per trillion, or 5 times lower than the PHG for Cr(VI). The EPA has a process similar to OEHHA’s for setting a Maximum Contaminant Level Goal (MCLG) which is analogous to the PHG. The MCLG that EPA has set for arsenic is 0 mg/L. “The International Agency for Research on Cancer (IARC) evaluated arsenic in 1980 and classified ‘arsenic and arsenic compounds’ in Group 1, which includes ‘chemicals and groups of chemicals, which are causally associated with cancer in humans.’ Arsenic is also known to be atherogenic, genotoxic, teratogenic, and may cause other adverse developmental effects in exposed children.’(2)

Setting PHG’s and MCLG’s is the first step in the regulatory process. These goals, along with other considerations such as Best Available Technologies (BAT) for treatment and what that treatment costs, are used to set the Maximum Contaminant Level (MCL), which is the regulatory level. The MCL for arsenic has been set at 10 ug/L, or 2,500 times higher than the PHG. Yet the political and public pressure is being applied to set the MCL for Cr(VI), a less toxic chemical by almost any measure, at or very near the PHG of 0.020 ug/L. The logic here is illusive to say the least.

I don’t think the MCL for arsenic should be lowered. There are too many small systems that can’t meet the MCL now, and many others can only meet it at great expense. That’s an expense that gets passed on to the consumer in a time when complaints about increasing water bills show up in the news a lot more frequently than news about Cr(VI). And I don’t think that the MCL for Cr(VI) should be set at or near the PHG. The same considerations that were used to set the MCL for arsenic 2,500 times higher than the PHG need to be applied to setting the MCL for Cr(VI). Water purity has to be balanced by water expense in providing an acceptable product to the public.

1) PUBLIC HEALTH GOALS FOR CHEMICALS IN DRINKING WATER, HEXAVALENT CHROMIUM (Cr VI), July 2011.  http://oehha.ca.gov/water/phg/pdf/Cr6PHG072911.pdf


2) PUBLIC HEALTH GOALS FOR CHEMICALS IN DRINKING WATER, ARSENIC, April 2004.
http://oehha.ca.gov/water/phg/pdf/asfinal.pdf

Time for Ag to Step Up and Reduce Nitrate Contamination

I find it incredibly disturbing that in California, a State with the 7^th largest economy of any country in the world, we have drinking water issues that we share with countries that are at the bottom of the economic ladder, the so called Third World Countries.  The United Nations even sent a Special Rapporteur, Catarina de Albuquerque, to the United States to report on safe drinking water and sanitation.  The report, available here - http://www2.ohchr.org/english/bodies/hrcouncil/docs/18session/A-HRC-18-33-Add4_en.pdf - was widely reported on in the press (http://newamericamedia.org/2011/09/un-report-california-county-lacks-clean-water.php ; http://articles.latimes.com/2011/apr/25/local/la-me-seville-water-20110425 ; http://www.californiaprogressreport.com/site/comment/reply/9877 ), and documents how terrible water quality conditions are in parts of California’s Central Valley, one of the most productive agricultural areas in the world.  The ground water aquifers in the area, from where most drinking water is drawn, are contaminated with nitrates, arsenic, and pesticides.  While the arsenic is most likely naturally occurring in many if not all of these areas, the nitrates and pesticides are definitely the result of intensive agricultural practices, which include both applications of nitrate fertilizers and the disposal of waste from concentrated animal feeding operations, or CAFO’s.  Currently, several of the Regional Water Quality Control Boards around California, because this is an issue not exclusive to the Central Valley,  are working on adopting new rules that will require agricultural entities to reduce groundwater and surface water pollution from nitrate fertilizers, pesticides and sediment carried from irrigated farm fields.  Needless to say, these regulations are hotly contested by the agricultural lobby as being too expensive and otherwise burdensome for farmers to deal with.  As a regulatory and water quality professional working in the highly regulated field of drinking water, I agree that regulations are burdensome, as well as irksome, but they are also highly necessary to protect public health, and it is more than past time for agriculture to step up and bear the responsibility for the havoc they are reeking on the ground water resources of this State.  Agriculture needs to stop foisting the problem off on to the residents of poverty stricken, politically orphaned, primarily Latino communities who suffer the economic damage and degraded health that is the result of this agricultural pollution.  Instead, they need to do the right thing by working hard and long, something farmers are very good at, to do the monitoring, reporting, and implementation of best management practices that will begin to turn this problem around and clean up California’s precious ground water resources.

Total Coliform Bacteria

A typical sample station for taking coliform
samples in the distribution system.

Every week, drinking water operators everywhere spend their morning driving from sample station to sample station, very carefully filling little 100 mL bottles with water from their distribution systems. At least once per quarter, and probably more often, they do the same thing for the water from each and every operating well in their systems. They cap the bottles, label them appropriately, and prepare them for transport to the laboratory where they will be tested for Total Coliform Bacteria. If the test is positive, then the sample will also be tested for a particular bacterium, Escherichia coli, more commonly known as E. coli. So what is a coliform bacterium and why do we test for it? Coliform bacteria are defined as rod-shaped Gram-negative non-spore forming bacteria which can ferment lactose with the production of acid and gas when incubated at 35-37°C (American Public Health Association, Standard Methods for the Examination of Water and Wastewater, 19th ed., APHA, Washington, DC, 1995). That’s a mouthful! In other words, a coliform bacterium is one that gives a positive test result; not a real meaningful definition. In theory, the coliform test is used to try and detect bacteria that may be present because of contamination by sewage or sewage contaminated water. A great many of the bacteria that live in the gut of mammals like humans are coliform bacteria. However, coliform bacteria can and do live just about anywhere; in the soil, in surface and groundwater, in and on plants, flowers and fruits, everywhere. So just because there may be a positive coliform sample doesn’t mean that the water is contaminated. It is just an indicator that there could possibly be a problem, and that you should do some investigating to see if there are any problems you weren’t aware of in your system; maybe a leak, an unprotected backflow situation, low chlorine residuals, etc. Drinking water systems are required to test for these bacteria in the distribution system by the U.S. Environmental Protection Agency’s Total Coliform Rule (TCR), and there are very specific steps that must be taken if a test result is positive, such as taking repeat samples. The TCR is currently being revised to better reflect the fact that a positive result does not necessarily mean the distribution system is contaminated. The revised rule is expected to be finalized later this year, and would go into effect in 2014. The California Department of Public Health (CDPH) requires that each well be tested at least quarterly, and there are no regulations related to a positive result. However many water companies, in an effort to more closely monitor and protect groundwater resources, have implemented monthly testing for their wells, and implement their own actions should a well test positive.

Although not necessarily indicative of any contamination, testing for coliform bacteria can be a very good tool for keeping track of the overall health and cleanliness of groundwater resources, the distribution system, and of the water we deliver to our customers. The job of taking all those samples is a very important one for system operators.

Carbon Disclosure Project Water Disclosure Global Report 2011

Published in late 2011, the Carbon Disclosure Project (CDP) Water Disclosure Global Report looks at corporate awareness of global water issues. A total of 238 companies responded to the information request that was the basis of the report, out of a total of 425 companies solicited for a response rate of 56%. That’s an enviable response rate for any such endeavor. Companies were chosen from the FTSE Global Equity Index Series, The Australian Securities Exchange, and The Johannesburg Stock Exchange. Key highlights from the report include:

• 59% of respondents report exposure to water related risk that has the potential to cause significant impact;
• 63% have identified water related opportunities to generate substantial change in revenues;
• Increasing numbers of companies are tracking water withdrawls and recycling/reuse data;
• Energy companies report a very high level of water related risk but a low level of board oversight of water issues.
In all, global companies are realizing the significance of water to their overall operations. As part of the information collection response, IBM replied, “Water …is fast becoming one of the planet’s most stressed resources. Access to clean water has emerged as a critical issue affecting economic activity, development, and business around the world.” Not to mention the importance to sustaining life itself for all the planets many and varied inhabitants. Read the full report here - https://www.cdproject.net/water .

Is So Cal Finally Getting Serious About Its Water Crisis?

This article from Time (http://ti.me/whFGlX ) does a good job giving an overview of Southern California’s start/stop/start again process for dealing with water self sufficiency. Every time there’s a drought, people run around screaming and yelling about reducing dependence on imported water and developing reliable local sources. The discussion includes conservation, recycling, stormwater capture, rainwater harvesting, increased groundwater use, and desalination. Plans are made, funding sources explored, consultants (lots of consultants) are contracted with to explore every aspect of each and every proposal. Then, of course, it rains, and everything comes to a screeching halt; who needs all of those expensive alternative water supply projects when the stuff is falling from the sky? It’s a problem that isn’t limited to the California southland; Australia, during a long and serious drought, was able to get several desalination plants built to try and drought-proof their water supply. Now that the drought there has eased a bit, many are questioning whether those plants are necessary or should have ever been built.


The people of Southern California will have to experience a great deal more pain from increased water costs and decreased availability before they will demand from their political institutions a determined, significant effort to reduce the dependence on imported water. The Time article indicates that the Los Angeles area has reuced it’s dependence on imported water by 25% in the past 20 years. At that rate, it will take at least another 60 years to reach water independence, which is way too long.

Why Is My Water So Hard?!?!?

 

Calcium
©2011 Inorganic Ventures, Inc.



Magnesium
©2011 Inorganic Ventures, Inc.

Who among us that live somewhere the water is hard haven’t asked that before ourselves? I certainly have, and I know why the water is hard.  It’s usually more a rhetorical cry of frustration than it is a cry for answers, but none the less, I thought someone out there might want to know a bit more about water hardness, both actual and perceived, so hold on to your hats, because here we go.  Water hardness is defined as the concentration of polyvalent cations, and is expressed as the equivalent concentration of calcium carbonate (CaCO₃) in mg/L.  Huh?  A cation is just an atom or molecule that has a positive electric charge and polyvalent means the positive charge is greater than +1.  So, for example, an atom of calcium dissolved in water is a polyvalent cation because it has a charge of +2, and is shown like this: Ca⁺².  Simple!  The most common polyvalent cations in drinking water that make up hardness are calcium (Ca⁺²) and magnesium (Mg⁺²), but can also include a whole host of ions such as iron, copper, zinc, nickel and others.  These latter elements are usually present in small enough quantities that they do not appreciably add to the hardness, however, so for the most part we can just consider calcium and magnesium.  The quantities for all these polyvalent cations that are included in hardness get converted to equivalent concentrations of calcium carbonate for simplicity and ease of comparing one sample to another.  Consumers like you and I for the most part don’t care about polyvalent/polyshmalent, cat-ions/dog-ions – all we care about is the spots on our glasses and that crusty stuff on our faucet.  Although hardness is a large part of that, it’s also affected by another measurement known as Total Dissolved Solids, or TDS.  That measurement is a bit easier to understand and is pretty much just as its name implies; it’s a measurement of all the stuff dissolved in the water.  It includes hardness, because the calcium and magnesium cations are a dissolved solid and therefore get included in TDS.  But it also includes things like sodium (Na⁺¹), sulfate (SO^-4), potassium (K⁺¹), chloride (Cl^-1) and others that can lead to those dreaded spots and crustiness when water is allowed to dry on glasses or fixtures, leaving the dissolved solids behind.  Many people also think of these compounds collectively as “salt”, and indeed when they dry, they do form salts such as the one we all know, sodium chloride or table salt, but also salts such as calcium sulfate or potassium chloride.  But fixture deposits and spotted dishes aren’t the only problems excessive hardness and TDS cause.  Over the years, calcium, magnesium, and TDS compounds can precipitate out of the water and form a coating on the insides of pipes in the distribution system or in home plumbing systems reducing the flow of water.  These precipitates can also collect in water heaters, reducing their efficiency, or plug up faucet aerators.  On the plus side, there have been some medical studies showing that the calcium and magnesium in hard water can be a significant part of the dietary intake necessary for good health, and that it can even be effective in lowering the incidence of cardiovascular disease.  Other medical studies have been inconclusive on this last point, so the jury is still out.   General hardness ratings are shown in the Table.  Where does all this stuff in the water come from?  For groundwater, the minerals in the water are those that have been dissolved from the local rocks and soils as the water moves through the aquifers beneath our feet.  Calcium, magnesium, and all the rest are very common in the local geologic structures, and water, being such a good solvent, is very effective at removing them.  Surface water, such as that in the California State Water Project, does not come in contact with rocks and soil for nearly as long as groundwater, so it has fewer of these elements dissolved in it, and therefore isn’t as hard.

Orange County Water District Groundwater Adventure Tour



Microfiltration units

Yesterday, November 10, 2011, the Orange County Water District (OCWD) held its annual tour of the Groundwater Replenishment System (GWRS), a state of the art system in Orange County, CA for recycling wastewater into drinking water and maximizing groundwater recharge from naturally occurring run-off in the Santa Ana River watershed. I was lucky enough to get a seat on the tour, which always seems to fill up fast, and along with about 150 other people, participated in the day long adventure.



Reverse osmosis cartridges



The GWRS is the world’s largest advanced wastewater purification system for indirect potable reuse.(1) The wastewater is purified using microfiltration (MF), reverse osmosis (RO), and advanced oxidation (AO) with hydrogen peroxide and ultra-violet (UV) light. The water that results meets all state and federal safe drinking water regulations for potable water. On the tour, they give you the opportunity to drink some, which I did; it tasted good, and I’ve had no ill effects, I assure you. However, rather than being used as a source of potable water directly, the water is either pumped into the ground near the coast as a barrier against seawater intrusion, or it is pumped to percolation basins so it can recharge the groundwater aquifer that underlies a large part of Orange County. The plant has a capacity of 70 million gallons per day (MGD). A 30 MGD expansion is currently in the planning stages, to be completed by 2014; and another 30 MGD expansion is planned for the future.



The far tap is the fully treated wastwater. Yummy!



The aquifer is also recharged by water draining from the Santa Ana River watershed. This recharge is enhanced by the use of rubber dams to divert the water into off-channel percolation basins, and by in-channel engineering that spreads the water out across the entire channel, maximizing the wetted area of the channel, which in turn maximizes percolation. The tour included a visit to one of the rubber dams and related off-channel features. These recharge efforts also include hundreds of acres of constructed wetlands in the area above Prado Dam, one of two large permanent dams on the river. These wetlands take water that drains from heavily agricultural areas, including large dairy farms, which is very high in nitrate, and allows natural biological attenuation to occur. The water leaving these wetlands, which flows into the recharge areas mentioned previously, has nitrate levels that are frequently non-detectable. This process prevents high nitrate water from percolating into the aquifer and causing widespread contamination. The tour group helped plant trees in the wetland area to help prevent erosion.

Inflatable rubber diversion dam on the Santa Ana River

The combination of the GWRS and the other recharge operations puts 230,000 acre-feet (AF) of water back into the aquifer every year; that’s almost half of the 500,000 AF of water that is used within the Orange County Water District.

It was a great tour, and a very educational day all around. I’d highly recommend it to anyone with an interest in water.

(1) The information is from the tour itself, and printed materials that were handed out.