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How Safe is Our Drinking Water?

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Guest Michele Quander-Collins

DC WASA is Leader in Protecting the Potomac River and Chesapeake Bay


The Chesapeake Bay is the largest estuary in the United States, and water quality is the most important measure of the Chesapeake Bays health. A number of restoration projects and programs, from 5 states and the District of Columbia, have been undertaken to improve the poor water quality in the Bay and address the degraded habitats and the low populations of many species of fish and shellfish. The District of Columbia Water and Sewer Authority continues to be a leader in this effort.

DC WASAs Blue Plains Advanced Wastewater Treatment Plant is the largest plant of its kind in the world, and is also the largest single point discharger to the Chesapeake Bay. DC WASA has long been a leader in working to clean up the Bay by voluntarily reducing nitrogen levels and annually exceeding goals established by the Chesapeake Bay Agreement in 1987 and 2000. (Nitrogen aids the growth of algae in the Bay, causing the depletion of oxygen needed by fish and other aquatic life).


Blue Plains is located at the southern tip of the District, on a 150-acre site along the Potomac River. Wastewater from the District and several counties in Maryland and Virginia is treated at Blue Plains and returned to the Potomac River. The Potomac is a tributary of the Chesapeake Bay. To further reduce nitrogen levels discharged into the Potomac, DC WASA is investing upwards of $1 billion for improvements at its Blue Plains facility.


While Blue Plains is the largest single point source discharger to the Chesapeake Bay, a Chesapeake Bay Commission Report documents that less than 26 percent of the Bays nitrogen is due to discharges from municipal wastewater treatment plants. Two- thirds of the nitrogen load in the Bay comes from agricultural and airborne influences.

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Naturally Occurring Sources of Pollution



•Microorganisms: Bacteria, viruses, parasites and other microorganisms are sometimes found in water. Shallow wells — those with water close to ground level — are at most risk. Runoff, or water flowing over the land surface, may pick up these pollutants from wildlife and soils. This is often the case after flooding. Some of these organisms can cause a variety of illnesses. Symptoms include nausea and diarrhea. These can occur shortly after drinking contaminated water. The effects could be short-term yet severe (similar to food poisoning) or might recur frequently or develop slowly over a long time.

•Radionuclides: Radionuclides are radioactive elements such as uranium and radium. They may be present in underlying rock and ground water

•Radon: Radon is a gas that is a natural product of the breakdown of uranium in the soil — can also pose a threat. Radon is most dangerous when inhaled and contributes to lung cancer. Although soil is the primary source, using household water containing Radon contributes to elevated indoor Radon levels. Radon is less dangerous when consumed in water, but remains a risk to health.

•Nitrates and Nitrites: Although high nitrate levels are usually due to human activities (see below), they may be found naturally in ground water. They come from the breakdown of nitrogen compounds in the soil. Flowing ground water picks them up from the soil. Drinking large amounts of nitrates and nitrites is particularly threatening to infants (for example, when mixed in formula).

•Heavy Metals: Underground rocks and soils may contain arsenic, cadmium, chromium, lead, and selenium. However, these contaminants are not often found in household wells at dangerous levels from natural sources.

•Fluoride: Fluoride is helpful in dental health, so many water systems add small amounts to drinking water. However, excessive consumption of naturally occurring fluoride can damage bone tissue. High levels of fluoride occur naturally in some areas. It may discolor teeth, but this is not a health risk.

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:huh:Human Activities Can Pollute Ground Water?


• Septic tanks are designed to have a “leach field” around them — an area where wastewater flows out of the tank. This wastewater can also move into the ground water.

Bacteria and Nitrates: These pollutants are found in human and animal wastes. Septic tanks can cause bacterial and nitrate pollution. So can large numbers of farm animals. Both septic systems and animal manures must be carefully managed to prevent pollution. Sanitary landfills and garbage dumps are also sources. Children and some adults are at extra risk when exposed to water-born bacteria. These include the elderly and people whose immune systems are weak due to AIDS or treatments for cancer. Fertilizers can add to nitrate problems. Nitrates cause a health threat in very young infants called “blue baby” syndrome. This condition disrupts oxygen flow in the blood.

•Concentrated Animal Feeding Operations (CAFOs): The number of CAFOs, often called “factory farms,” is growing. On these farms thousands of animals are raised in a small space. The large amounts of animal wastes/manures from these farms can threaten water supplies. Strict and careful manure management is needed to prevent pathogen and nutrient problems. Salts from high levels of manures can also pollute ground water.

•Heavy Metals: Activities such as mining and construction can release large amounts of heavy metals into nearby ground water sources. Some older fruit orchards may contain high levels of arsenic, once used as a pesticide. At high levels, these metals pose a health risk.

•Fertilizers and Pesticides: Farmers use fertilizers and pesticides to promote growth and reduce insect damage. These products are also used on golf courses and suburban lawns and gardens. The chemicals in these products may end up in ground water. Such pollution depends on the types and amounts of chemicals used and how they are applied. Local environmental conditions (soil types, seasonal snow and rainfall) also affect this pollution. Many fertilizers contain forms of nitrogen that can break down into harmful nitrates. This could add to other sources of nitrates mentioned above. Some underground agricultural drainage systems collect fertilizers and pesticides. This polluted water can pose problems to ground water and local streams and rivers. In addition, chemicals used to treat buildings and homes for termites or other pests may also pose a threat. Again, the possibility of problems depends on the amount and kind of chemicals. The types of soil and the amount of water moving through the soil also play a role.

•Industrial Products and Wastes: Many harmful chemicals are used widely in local business and industry. These can become drinking water pollutants if not well managed. The most common sources of such problems are:

◦Local Businesses: These include nearby factories, industrial plants, and even small businesses such as gas stations and dry cleaners. All handle a variety of hazardous chemicals that need careful management. Spills and improper disposal of these chemicals or of industrial wastes can threaten ground water supplies.

◦Leaking Underground Tanks & Piping: Petroleum products, chemicals, and wastes stored in underground storage tanks and pipes may end up in the ground water. Tanks and piping leak if they are constructed or installed improperly. Steel tanks and piping corrode with age. Tanks are often found on farms. The possibility of leaking tanks is great on old, abandoned farm sites. Farm tanks are exempt from the EPA rules for petroleum and chemical tanks.

◦Landfills and Waste Dumps: Modern landfills are designed to contain any leaking liquids. But floods can carry them over the barriers. Older dumpsites may have a wide variety of pollutants that can seep into ground water.

•Household Wastes: Improper disposal of many common products can pollute ground water. These include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and detergents can harm drinking water. These are often a problem from faulty septic tanks and septic leaching fields.

•Lead & Copper: Household plumbing materials are the most common source of lead and copper in home drinking water. Corrosive water may cause metals in pipes or soldered joints to leach into your tap water. Your water’s acidity or alkalinity (often measured as pH) greatly affects corrosion. Temperature and mineral content also affect how corrosive it is. They are often used in pipes, solder, or plumbing fixtures. Lead can cause serious damage to the brain, kidneys, nervous system, and red blood cells. The age of plumbing materials — in particular, copper pipes soldered with lead — is also important. Even in relatively low amounts these metals can be harmful. EPA rules under the Safe Drinking Water Act limit lead in drinking water to 15 parts per billion. Since 1988 the Act only allows “lead free” pipe, solder, and flux in drinking water systems. The law covers both new installations and repairs of plumbing.

◦For more information on avoiding lead in drinking water, visit the EPA's Lead in Drinking Water web site.

•Water Treatment Chemicals: Improper handling or storage of water-well treatment chemicals (disinfectants, corrosion inhibitors, etc.) close to your well can cause problems.

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Cumulative TMDLs by Pollutant

District Of Columbia, Middle Potomac-Anacostia-Occoquan Watershed

This chart includes TMDLs since October 1, 1995.


Below is a list of all pollutants or stressors that are causing impairment in assessed waters of the watershed and the number of miles, acres, or square miles that are impaired by each cause in each waterbody type. While most of the cause names (such as nutrients or metals) are standard and widely used by all states, others may be unique to a given state.


Pollutant Number of TMDLs Completed Number of Causes of

Impairment Addressed



DDT 25 25

Dieldrin 25 25

Heptachlor Epoxide 25 25

PAH1 - 2 & 3 Ring Polycyclic Aromatic Hydrocarbons 25 25

PAH2 - 4 Ring Polycyclic Aromatic Hydrocarbons 25 25

PAH3 - 5 && Ring Polycyclic Aromatic Hydrocarbons 25 25

Chlordane 24 24

DDE 24 24

DDD 23 23

Fecal Coliform 22 22

Polychlorinated Biphenyls (PCBs) 19 19

Copper 16 16

Lead 16 16

Zinc 16 16

Arsenic 14 14

Pathogens 9 9

Biochemical Oxygen Demand (BOD) 6 6

Suspended Solids 5 5

Oil and Grease 4 4

Mercury 2 2

Nitrogen 2 2

Phosphorus 2 2

Suspended Sediment 2 2

Toxics 2 2

pH 2 2


Total: 360 TMDLs; 360 Causes of Impairment




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Guest Guest



Cryptosporidium is a microbial pathogen found in surface water throughout the U.S. Although filtration removes Cryptosporidium, the most commonly-used filtration methods cannot guarantee 100 percent removal.


EPA only requires monitoring of our source water for Cryptosporidium because the approved test method is not sensitive enough to reliably detect the minimal remaining organisms (if any) in the treated water.


Cryptosporidium was not detected in our required monitoring in 2007 for our Patuxent source water, but our required monitoring for our Potomac source water indicated the presence of these organisms in 2 of the 24 samples collected.


Current test methods do not allow us to determine if the organisms are dead or if they are capable of causing disease. Based on our Cryptosporidium monitoring results to date for the Potomac source water, our existing treatment process is anticipated to meet pending EPA requirements for treatment of Cryptosporidium; nevertheless, as a precaution, we are proceeding with the installation

of UV disinfection to provide an extra barrier of protection against Cryptosporidium.


Cryptosporidium must be ingested to cause disease, and it may be spread through means other than drinking water. Ingestion of Cryptosporidium may cause cryptosporidiosis, an abdominal infection.


Symptoms of infection include nausea, diarrhea, and abdominal cramps. Most healthy individuals can overcome the disease within a few weeks. However, immuno-compromised people, infants and small children, and the elderly are at greater risk of developing life threatening illness.


Potential sources of contamination in the Potomac River watershed include urban and agricultural land uses, and potential spills from highways and petroleum pipelines. Contaminants of particular concern include natural organic matter and disinfection by-product (DBP) precursors, pathogenic microorganisms (Cryptosporidium, Giardia, fecal coliform), taste and odor causing compounds, ammonia, sediment/turbidity, and algae.

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extremely small amounts of three compounds in the Potomac River source water were detected. They were:


• Atrazine – a commonly used herbicide for maize products – found at 0.1

parts per billion.

• Carbamazepine – an anti-epileptic medication – found at a maximum of

0.012 parts per billion; and

• Sulfamethoxazole – an antibiotic – found at 0.003 parts per billion.



Atrazine and carbamazepine were found in the Washington Suburban Sanitary Commission’s treated waters.


Atrazine was detected at a level of 0.1 parts per billion in the drinking water from the Potomac River, and at 0.3 parts per billion in the drinking water from the Patuxent River. This concentration of atrazine is ten times lower than the Maximum Contaminant Level (MCL) set by the EPA, which is 3 parts per billion.


The concentration of carbamazepine was 0.010 parts per billion in the drinking water from the Potomac River, but none was detected in the Patuxent River drinking water. The detected level of carbamazepine in drinking water from the Potomac River is about 1,200 times lower than a conservatively estimated acceptable daily intake level of 12 parts per billion.

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Guest Marty_*

The Washington Suburban Sanitary Commission, Fairfax Water and the Washington Aqueduct, along with many water utilities across the nation, have contributed to and participated with the American Water Works

Association Research Foundation (AwwaRF) to study endocrine disruptors, personal care products and pharmaceuticals. To date, AwwaRF has conducted 21 projects on this subject totaling approximately $4.9 million.

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Guest Chesapeake Wildlife

Last year, researchers with the U.S. Geological Survey found male fish with immature female eggs, right here in the Potomac River.


What’s in the water?


These fish, called intersex fish, may occur as a result of chemicals in the water that mimic or antagonize hormone levels. Known as endocrine disruptors, these substances can interfere with an organism’s normal hormone functions. Endocrine disruption has the potential to compromise proper development, leading to reproductive, behavioral, immune system and neurological problems, as well as the development of cancer.


Endocrine disruptor compounds can enter a waterway from sewage outfalls, industrial and municipal pollution, and agricultural runoff. Endocrine disruptors may be entering the Potomac River watershed through synthetic estrogen, such as those in birth control pills and hormone replacement therapy, or from those hormones associated with livestock operations.


Current Research


Federal agencies are now investigating the effects of organic pollutants and endocrine disruptors on hormone activity in fish in the Potomac River watershed. The U.S. Fish & Wildlife Service and our partners at U.S. Geological Survey, Maryland Department of Natural Resources and D.C. Department of the Environment (formerly the Department of Health), collected water samples and fish at various sites in the Potomac River watershed.


Smallmouth and largemouth bass were selected as the target fish because they are sensitive to pollution and frequently display the physical symptoms of intersex. Biologists measured concentrations of endocrine disruptor chemicals in the water and sampled bass from the Monocacy River and Conococheague Creek in Washington County, Maryland, and the Potomac River in Washington, D.C.




Eighty to 100 percent of the male smallmouth and 30-35 percent of the largemouth bass exhibited intersexbass collected at all sites exhibited intersex. Both sexes at all sites had relatively low gonadosomatic indexes (GSI), meaning their gonads were especially light-weight relative to body weight.


Current Status


Further research to determine the extent, causes, and population impacts of intersex and other forms of endocrine disruption is needed.


Coordination across State lines (e.g., West Virginia, Virginia, Maryland, Pennsylvania and District of Columbia) and a comprehensive watershed evaluation are essential components of a long-term plan to address endocrine disruptors in the Potomac River.


For more information, please contact Chris Guy at (410)573-4529.

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Guest RTP Procurement

EPA needs new treatment and measurement technologies for organic and inorganic contaminants and disease-causing organisms, especially for small systems. Microorganisms of concern include Cryptosporidium and other cyst-like organisms and emerging pathogens such as caliciviruses, microsporidia, echoviruses, coxsackieviruses, adenoviruses, and others.


Areas of interest include, but are not limited to:


Improved detection and measurement techniques including screening kits for algal neurotoxins (especially cyanobacterial anatoxin) and cytotoxins in drinking water systems.


Improved detection and measurement techniques for microbial pathogens that also address viability or infectivity, including online devices for continuous monitoring of pathogens and optimization of three-dimensional cell culture systems for growth of waterborne enteric viruses and bacteria for routine laboratory use.


New amplification systems used in conjunction with microarrays that detect multiple classes of pathogens (viruses, protozoa, bacteria) found in water and improved microfluidics-based devices for concentrating organisms in large volume samples.


Field test kits for rapid, cost-effective detection of Type E Botulism Toxin. Botulism is a neuromuscular disease caused by several strains of Clostridium botulinum. The toxin is often produced when spores in sediments germinate and the bacterium enters the vegetative growth cycle. Type E is one of the strains that cause human botulism and it has caused waterfowl and fish kills in the Great Lakes and other US waters.


Development of innovative unit processes, particularly for small drinking water systems, for removal or inactivation of contaminants such as pesticides, organic pollutants, pharmaceuticals and personal care products and pathogens.


EPA SBIR Program Solicitation No. PR-NC-09-10319


U.S. Environmental Protection Agency

Solicitation No. PR-NC-09-10319 - SBIR Phase I

Closing Date: May 20, 2009 at 12:00 p.m. (Noon)

Attention: Stacey Passwaters, SBIR Phase I

RTP Procurement Operations Division (E105-02)

Research Triangle Park, NC 27711


All inquiries concerning this solicitation shall be submitted to the following E-mail address:


If E-mail is not available to you, written or telephone inquiries may be directed to:

U.S. Environmental Protection Agency

Attention: Stacey Passwaters, SBIR Phase I

RTP Procurement Operations Division (E105-02)

Research Triangle Park, N.C. 27711

Telephone: (919) 541-1344

Fax: (919) 685-3196

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Guest toxic

Microbial Contaminant Candidates


Caliciviruses Virus (includes Norovirus) - causing mild self-limiting gastrointestinal illness

Campylobacter jejuni Bacterium - causing mild self-limiting gastroentestinal illness

Entamoeba histolytica Protozoan - parasite which can cause short as well as long-lasting gastrointestinal illness

Escherichia coli (0157) - Toxin-producing bacterium causing gastrointestinal illness and kidney failure

Helicobacter pylori Bacterium - sometimes found in the environment capable of colonizing human gut that can cause ulcers and cancer

Hepatitis A virus - Virus that causes a liver disease and jaundice

Legionella pneumophila Bacterium - found in the environment including hot water systems causing lung diseases when inhaled

Naegleria fowleri Protozoan - parasite found in shallow, warm surface and ground water causing primary amebic meningoencephalitis

Salmonella enterica Bacterium - causing mild self-limiting gastrointestinal illness

Shigella sonnei Bacterium - causing mild self-limiting gastrointestinal illness and bloody diarrhea

Vibrio cholerae Bacterium - found in the environment causing gastrointestinal illness

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Guest Wesley

Toxaphene is considered as an endocrine disruptor, because it mimics estrogen and may produce reversible, or irreversible biological effects in individuals by interfering with normal hormone function. Endocrine disruptors act through a number of mechanisms by temporary, or permanently altering feedback loops involving the brain, pituitary, testes, ovary, thyroid gland, or other organs. Their actions are attributed to mimicking, or interfering with normal functioning of sex hormones such as estrogen, progesterone, and testosterone.


ATSDR’s oral intermediate (15 to 365 days) Minimal Risk Level ( MRL )for toxaphene is at 0.001 mg/kg/d ( milligrams/kilogram/day ) which is based on adverse liver effects in animals studies. An MRL is the amount of chemical that the general population can be exposed to over a specified duration that is unlikely to result in adverse health effects. The MRL is based on acute exposure (1 to 14 days); intermediate exposure (15 to 365 days); and chronic exposure (greater than 365 days).

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Guest LAW_*

Toxaphene is an insecticide containing over 670 chemicals. It is usually found as a solid or gas, and in its original form it is a yellow to amber waxy solid that smells like turpentine.


It does not burn and evaporates when in solid form or when mixed with liquids. Toxaphene is also known as camphechlor, chlorocamphene, polychlorocamphene, and chlorinated camphene.


Toxaphene was one of the most heavily used insecticides in the United States until 1982, when it was canceled for most uses; all uses were banned in 1990. It was used primarily in the southern United States to control insect pests on cotton and other crops. It was also used to control insect pests on livestock and to kill unwanted fish in lakes.

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Guest Rookie

Camphechlor residues generally occur in agricultural crops as well as in meat from domestic livestock and fish.


Camphechlor residues on growing leafy crops have a half-life of 5 - 10 days.


On alfalfa and clover, the half-life is in the range of 9 - 13 days.


The residue level is controlled by time of application, dosage rate, and appropriate pre-slaughter or pre-harvest intervals (WHO, 1975).


Because livestock is treated with camphechlor to remove external insects and because some feeds are contaminated with camphechlor, camphechlor residues are found in meat and poultry.


Camphechlor, when fed to rats for 7 days at 25 mg/kg diet, caused an increase in the metabolism of estrone and inhibited the increase in uterine weight produced by this compound (Welch et

al., 1971).

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Guest elbrus

You might check out Halogenated Organic Compounds



Simple aromatic halogenated organic compounds are very unreactive; halogenated aliphatic compounds are moderately or very reactive. For both subgroups, reactivity generally decreases with increased degree of substitution of halogen for hydrogen atoms. Halogenated acetylene compounds are unstable and should be treated as explosives. Low molecular weight haloalkanes are highly flammable and can react with some metals to form dangerous products. Low molecular weight haloalkenes are highly flammable, peroxidizable and may polymerize violently. They may react violently with aluminum. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they are incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides.



Many halogenated hydrocarbons have moderate to high toxicity by inhalation. The brominated materials tend to be particularly toxic. Much of the toxicity is due to the fact that these substances are not metabolized, but persist and accumulate in fatty tissues (they tend to be fat-soluble). The combustion of chlorinated organic compounds may produce poisonous phosgene gas (COCl2). Other materials formed by incomplete combustion are classes of chlorinated organic compounds, chlorodibenzodioxins and chlorodibenzofurans. These compounds cause cancer in laboratory tests.


Other Characteristics

This class of compounds is extremely important in industry in the production of polymers, pesticides, and fire retardants.

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Guest mayhem

Conventional waste water treatment focuses mostly on lowering pathogenic bacteria to minimize threats to human health and reduce nitrogen and phosphorus levels that cause excessive algal growth and low dissolved oxygen in aquatic environments.


While conventional treatment process have shown a somewhat limited ability to remove some of these trace organics, plants that utilize nitrification/denitrification and other advanced processes have proven to be much more effective, although at higher costs (LaGuardia; Mills).


Since endocrine disruptors are mostly organics, the chemicals are fairly resistant to the technologies developed to treat pathogens and inorganic compounds at wastewater facilities.


Anaerobic processing is a model example of a wastewater treatment technology that is extremely effective in reducing environmental impairment from nitrogen compounds, but largely inadequate for treating EDCs. This process diverts substantial amounts of biologically-active nitrogen away from effluent-receiving waters by converting the compounds into inert nitrogen gas. Yet, this treatment removes less than 10% of reactive EDCs, concentrating the remaining >90% in biosolids.

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The Sierra Club and several other organizations submitted a petition to US EPA calling for various actions and testing requirements on nonylphenol (NP) and nonylphenol ethoxylates (NPE). NPE are chemicals that function as surfactants in many applications including detergents and cleaning products. NPE have been used for over 50 years because they are high performance, cost-effective ingredients.


EPA established federal Water Quality Criteria (WQC) for NP in 2006. The WQC represents the

concentrations of NP in the aquatic environment that, when not exceeded, protect aquatic life. It is noteworthy that concentrations of NP/NPE measured in US waters over a period of 15 years have found very few samples that exceed the WQC level.


According to EPA’s final WQC document, "the ability of nonylphenol to induce estrogenic effects has seldom been reported at concentrations below the freshwater final chronic value of 6.5965 μg/L.”


Traditional chronic and multi-generational toxicity studies look at reproductive and developmental effects that are indicative of endocrine modulation, a term considered by many scientists to be a mechanism of action, not a toxicological endpoint.


The studies show that NP, which has weak estrogenic activity, is ten thousand to one million times less potent than the natural estrogen found in human waste. Moreover, the NPE used in

commercial products are not estrogenic. This is an important distinction because these are the compounds (the ethoxylates) that are used in the workplace.


Several of the tests that the petition advocates that EPA mandate have already been conducted. For example, a dermal absorption study on both NP and NPE was conducted by the North Carolina State University and published in a peer-reviewed journal. That study found that the ability of these compounds to enter the body through skin contact is minimal to negligible The results of mammalian toxicity studies conducted on NP and NPE, combined with an understanding of occupational and consumer exposure, support the conclusion that human safety should not be a concern for

these chemicals.


This view was confirmed in governmental risk assessments conducted by the European Union

and Canada. An assessment of the hazard and exposure information combined with the long history of use confirms that NPE are suitable for their intended uses.

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Guest LaGuardia

Research indicates promising strategies to mitigate transmission of EDCs into soil and water. This factsheet, and the associated forum held on November 16, 2006, only discussed exposure through watershed processes – and it is important to recognize that transmission of these compounds can occur through other media. While more research and economic assessments are required, some possible additions to advanced treatment at WWTPs include photolysis, ozonation, and chemical oxidation. WWTPs can also facilitate the degradation of the EDCs accumulated in biosolids by maintaining aerobic soils (Jacobsen et al., 2005). For agricultural facilities, like CAFOs, composting at elevated temperatures for long periods (>120oF for 139 d) can remove 84-90% of the concentrated EDCs (Millner and Hakk). However, temperature regulation, carbon and nitrogen supply, acreage, and manpower may limit practical adoption of this strategy.


Researchers are still working to better understand how these compounds affect endocrine function. As the number of confirmed EDCs continues to expand, research and management organizations will require technologies and strategies for greater detection, treatment, and remediation. These agencies will need to assess the toxicity of single compounds, compound mixtures, and any degradation products, while also working to understand how acute and chronic exposure affects endocrine functioning two to three generations after contact. The fate of EDCs in waste treatment by-products, such as biosolids, should also be determined to assure public confidence in crops and animals associated with EDC-treated soils. To assure that cumulative evidence governs regulatory decisions on product use, alternative animal models must be accepted by the assessment and regulatory community.


Ultimately, the best means for controlling EDC transmission is to reduce the production and inclusion of synthetic compounds in commercial products (Halden; Myers). Doing so will minimize future EDC loads to the watershed will allows historically deposited compounds to attenuate to safe or non-detectable levels.

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Guest softwood

UV filters used in sunscreeens and other personal care products may have hormonal effects in aquatic systems, according to Swiss scientists.


The levels of some chemicals that lead to disruptions in the hormonal system of fish are not much higher than those found in the lakes and rivers of Switzerland. For some compounds such as 3BC the margin of safety is very low,' he said.


Fent's work looks at organic filters such as 3BC (3-benzylidene camphor) that absorb UV rays rather then reflecting them like titanium dioxide and zinc oxide.


Such filters can enter an aquatic environment either directly from wash off from user's body, clothing and towels, or pass by a water treatment plant, he explained.

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Guest Ranter

Strategies for water quality improvement in agricultural watersheds often include filter strips. Filter strips are installed to reduce the load of sediment, nutrients, and other pollutants in surface runoff from fields that may otherwise reach waterways. Proper design can help ensure that a filter strip will achieve a desired level of impact.


Filter strips as narrow as 4 m (13.1 ft) were estimated to trap nearly 100% of the incoming material in some cases, while 30-m (98.4-ft) strips trapped only 10% of the load in other cases. The trapping efficiency of a given width of filter strip depends very strongly on the kind of material being trapped

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  • 3 weeks later...
Guest Yvonne Andersson

There are millions of people around the world who may be suffering needlessly because they are unaware of the symptoms and impact of thyroid disorders. Since thyroid hormones regulate the metabolism, an overactive or underactive thyroid gland can produce a wide variety of symptoms; but more importantly is that left untreated these symptoms can potentially lead to life-threatening complications

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