Evaluating Nanoparticle Breakthrough during Drinking Water Treatment

Use of engineered nanoparticles (NPs) in consumer products is resulting in NPs entering drinking water sources. Subsequent NP breakthrough into treated drinking water is a potential exposure route and human health threat.

 Objectives: 

This study investigated the breakthrough of common NPs, silver, titanium dioxide (TiO₂), and zinc oxide (ZnO), into finished drinking water following conventional and advanced treatment.

Methods: 

NPs were spiked into five experimental waters: groundwater, surface water, synthetic freshwater, synthetic freshwater with natural organic matter, and tertiary wastewater effluent. Bench scale coagulation/flocculation/sedimentation simulated conventional treatment, and microfiltration (MF) and ultrafiltration (UF) simulated advanced treatment.

Breakthrough of NPs into treated water was monitored by turbidity removal and inductively coupled plasma – mass spectrometry (ICP-MS).

Results: 

Conventional treatment resulted in 2-20%, 3-8%, and 48-99% of silver, TiO₂, and ZnO NPs or their dissolved ions remaining in finished water, respectively. Breakthrough following MF was 1-45% for silver, 0-44% for TiO₂, and 36-83% for ZnO. With UF, NP breakthrough was 0-2%, 0-4%, and 2-96% for silver, TiO₂, and ZnO, respectively. Variability was dependent on NP stability with less breakthrough of aggregated NPs compared to stable NPs and dissolved NP ions.

Conclusions: 

Although a majority of aggregated or stable NPs were removed by simulated conventional and advanced treatment, NP metals were detectable in finished water. As environmental NP concentrations increase, we need to consider NPs as emerging drinking water contaminants, and determine appropriate drinking water treatment processes to fully remove NPs in an effort to reduce their potential harmful health outcomes.

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New study: Many flame retardants in house dust -- unsafe levels | Science Codex

From Science Codex, Nov. 28, 2012

"A peer-reviewed study of the largest number of flame retardants ever tested in homes found that most houses had levels of at least one flame retardant that exceeded a federal health guideline. The journal Environmental Science & Technology will publish the study online on November 28, 12:01am Eastern. 

"The study led by scientists at Silent Spring Institute tested for 49 flame retardant chemicals in household dust, the main route of exposure for people and especially for children. Forty-four flame retardant chemicals were detected and 36 were found in at least 50% of the samples, sometimes at levels of health concern. The flame retardants found in house dust are in furniture, textiles, electronics, and other products and include hormone disruptors, carcinogens, and chemicals with unknown safety profiles. 

"The highest concentrations were found for chlorinated organophosphate flame retardants. This chemical group includes TCEP and TDCIPP (or chlorinated "Tris"), which are listed as carcinogens under California's Proposition 65. 

"TDBPP (or brominated "Tris") was banned from children's pajamas in 1977 due to health concerns but is still allowed in other products, and was present in 75% of homes tested in 2011.
There are no federal rules requiring that flame retardants be safety tested. Among the limited number of flame retardants with EPA health risk guidelines, the study found five at levels higher than those guidelines -- BDE 47, BDE 99, TCEP, TDCIPP and BB 153


Read the rest in Science Codex

Office workers carry biomarker of potentially harmful flame retardant, study finds | Science Codex

From Science Codex, March 25, 2013

"A flame retardant removed from children's pajamas 30 years ago but now used in polyurethane foam is prevalent in office environments, especially in older buildings, where urine testing of workers turned up widespread evidence of its biomarker, a new study led by Boston University School of Public Health researchers has found.
 
"The study, published in the journal Environment International, found that the chemical known as TDCPP -- chlorinated tris(1,3-dichloro-2-propyl) phosphate, or 'chlorinated tris' -- was present in 99 percent of dust samples taken from participants' homes, vehicles and offices, "demonstrating the widespread presence of this flame retardant in the indoor environment." The research team recruited 31 adults who worked and lived in the Boston area for the testing.

"The study found that the office environment was the strongest predictor of metabolized TDCPP in urine, with significantly lower concentrations of the chemical among workers in a new office building than in older buildings. Similarly, the average concentration of TDCPP in dust was significantly lower in the new office building than in the older office buildings."


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Study finds increasing atmospheric concentrations of new flame retardants | Science Codex

From Science Codex:

"Compounds used in new flame-retardant products are showing up in the environment at increasing concentrations, according to a recent study by researchers at Indiana University Bloomington.

"The study, published in the journal Environmental Science & Technology, reports on concentrations of two compounds measured in atmospheric samples collected in the Great Lakes region between 2008 and 2010. Authors are doctoral student Yuning Ma, Assistant Research Scientist Marta Venier and Distinguished Professor Ronald A. Hites, all of the IU School of Public and Environmental Affairs.

"The chemicals -- 2-ethylhexyl tetrabromobenzoate, also known as TBB; and bis(2-ethylhexyl) tetrabromophthalate, or TBPH -- are used to reduce flammability in such products as electronic devices, textiles, plastics, coatings and polyurethane foams.

"They are included in commercial mixtures that were introduced in recent years to replace polybrominated diphenylethers (PBDEs), widely used flame retardants that have been or are being removed from the market because of their tendency to leak from products into the environment."

Read the rest in Science Codex.

Study finds flame retardants at high levels in pet dogs

From Science Codex

"Indiana University scientists have found chemical flame retardants in the blood of pet dogs at concentrations five to 10 times higher than in humans, but lower than levels found in a previous study of cats.

"Their study, "Flame Retardants in the Serum of Pet Dogs and in their Food," appeared in April 2011 in the journal Environmental Science & Technology. Authors are Marta Venier, an assistant research scientist in the School of Public and Environmental Affairs, and Ronald Hites, a Distinguished Professor in SPEA.

"Venier and Hites explore whether pets could serve as "biosentinels" for monitoring human exposure to compounds present in the households that they share. Dogs may be better proxies than cats, they say, because a dog's metabolism is better equipped to break down the chemicals. 

"The study focuses on the presence of polybrominated diphenyl ethers (PBDEs) in the blood of dogs and in commercial dog food. PBDEs have been widely used as flame retardants in household furniture and electronics equipment. The compounds can migrate out of the products and enter the environment."

 Read the rest in Science Codex.

Common Household Chemical Is Powerful Endocrine Disruptor

A common chemical compound found in a wide range of household products is the prime suspect for widespread liver tumors found in California's marine estuaries by researchers from California Polytechnical State University, San Luis Obispo.

According to a journal paper article published in Chemosphere [87 (2012) 490-97)] the compound is nonylphenol ethoxylate which is banned in Europe, but widely used in the United States as a stabilizer in plastics, a spermicide in contraceptives, a softening agent in toilet paper and a surfactant (wetting agent) in detergents, agricultural sprays and personal care products.

What's more, the wastewater treatment process creates an endocrine disrupting compound (EDC) -- 4-nonynlphenol (4-NP) -- that builds up in the environment and accumulates in the food chain.

4-NP acts as a "xenoestrogen" (xeno- meaning, foreign, not native to an organism) and has been shown to disrupt reproduction and cause liver damage in fish and other marine organisms.

The CalPoly researchers looked at four California estuaries -- Morro Bay, San Francisco Bay, Drake's Bay and Tomales Bay.

They found that  4-NP accumulated in the food chain at every step, from ghost shrimp, mussels and oysters up through fish, seabirds and mammals.

While the NP-4 concentrations were some times as low as 1 nanogram/liter, the bioaccumulation factors at the top of the food chain (mammals) were 1,793 to 8,762 times higher for Sea Lions and Otters.

No inference was drawn for human consumption.

---

The distribution of 4-nonylphenol in marine organisms of North American Pacific Coast estuaries

• Jennifer Diehl, Sarah E. Johnson, Kang Xia, Amy West  Lars Tomanek

• http://dx.doi.org/10.1016/j.chemosphere.2011.12.040

Non-Monotonic Chemicals: Why They Matter

MONOTONIC VERSUS NON-MONOTONIC

The lack of predictability is a serious flaw in the current government method which  assumes that the chemical being tested always expresses itself the same way at every concentration. It assumes a greater effect at high concentration, a lesser effect at lower doses. In scientific terms, this predictability is called a monotonic dose response.

But EDCs and many other compounds are not so predictable because they affect different biological structures when present in varying concentrations. This is especially true for natural hormones, endocrine disrupters, many pharmaceuticals and even the ethanol in wine, beer and spirits.

The Vandenberg/Myers study explained that, “For all monotonic responses, the observed effects may be linear or nonlinear, but the slope [of the plotted line or curve] does not change sign. This assumption justifies using high-dose testing as the standard for assessing chemical safety. When it is violated, high-dose testing regimes cannot be used to assess the safety of low doses.”

The study then pointed out that EDCs as a group violate the rule by being non-monotonic.

WHY DOES NON-MONOTONIC MATTER?

Many chemical compounds are simply toxic: they damage and kill cells. The higher the concentration, the more toxic and the more cells die – the dose makes the poison.
Regardless of the concentration, these chemicals kill cells the same way. And, at the level of no observed adverse effects, they stop killing, or are tolerated by cells. This is a monotonic dose response.

But non-monotonic chemicals can affect different mechanisms in the body depending on the concentration.

One well-known non-monotonic response is the “U” shaped curve of the “French Paradox” or the activity of pharmaceuticals including aspirin and many hormones.

With these compounds, there is no effect at low concentrations. As concentration levels increase, scientific studies show an increasing beneficial effect. Then, beyond that level, the beneficial effect diminishes and later, high levels can be toxic and damaging.

This odd behavior is non-monotonic because the substances act on different parts of the body at different concentrations. At high levels they are toxic. At lower levels, they act on a variety of microscopic cell receptors and structures that allow them to have a different and beneficial effect.
Indeed, research has shown that at very low levels, EDCs can magnify or suppress the effects of natural hormones in the body or cause their own unique syndromes.

But nothing in nature says non-monotonic behavior always goes from damaging to beneficial as the concentrations go from high to low. Significantly, the effects of EDCs and other low-concentration chemicals are generally unstudied and unknown. However, in those few cases where they are better understood, EDCs have been found to have damaging effects.

Clearly, EDCs are an example of non-monotonic behavior that can go from deadly toxic (poisoning cells) to invisibly deadly (tumors, genetic effects, metabolic disorders and other diseases).

Indeed, as a future article in this series will explore, an increasing number of studies indicate that EDCs may be responsible for part of the current obesity and diabetes epidemics. They may also contribute to the decline of endangered species including salmon, frogs and other “cold-blooded” animals which seem to be more susceptible than mammals to chemical compounds.

Toxic Irrigation: Hazardous Chemicals Found in Recycled Wastewater Used For Vineyards And Other Crops

Recycled wastewater may more hazardous to use for crop and landscape irrigation than previously thought due to flaws in the way danger thresholds are currently determined.

NOTE: This article originally appeared in the June 14, 2010 issue of Wine Industry Insight. 

By Lewis Perdue

According to a major study published in June 2012 in the peer-reviewed scientific journal Endocrine Reviews, the current risk assessment methods to assess the dangers of endocrine disrupting compounds (EDCs) found in treated wastewater are severely flawed.

EDCs – including estrogens from birth control pills, powerful antibiotics, plasticizers like BPA and many other chemicals -- can disrupt or mimic human hormones in unpredictable ways even in the extremely small concentrations that are currently disregarded as inconsequential by government regulators. Many of the EDCs and chemicals find their way into wastewater by being flushed down a toilet or sink.

"Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities," concluded the study.

MASSIVE SCIENTIFIC UNDERTAKING

The massive scientific paper cited 845 other studies and was created by a team of twelve scientists led by Laura N. Vandenberg of the Tufts University Center for Regenerative and Developmental Biology, Medford, MA and by J. P. Myers of Environmental Health Sciences, Charlottesville, VA.
Other institutions represented by investigators of the study included:

• The University of California,
• Massachusetts General Hospital,
• National Institutes of Environmental Health Sciences,
• National Institutes of Health,
•  Department of Health and Human Services,
• University of Minnesota School of Public Health

Their work was supported by the National Institutes of Health and also by grants from a number of foundations including the Susan G. Komen Foundation, the Mitchell Kapor Foundation, Cornell-Douglas Foundation, the Wallace Global Fund and the Kendeda Foundation.
More information about the investigators and their connections can be found at the end of this article.

CONSEQUENCES FOR NORTH COAST AND OTHER CALIFORNIA VINEYARDS

While the Vandenberg/Myers study did not deal specifically with irrigation, it focused on many of the same chemical compounds found in the same concentrations as in treated wastewater used for irrigation.

For that reason, the study’s conclusions hold serious consequences for industrial and recreational landscape irrigation as well as the thousands of acres of premium California vineyards currently irrigated with highly treated wastewater.

Significantly for winegrape growers and ordinary citizens, every recent Environmental Impact Report (EIR) on treated wastewater irrigation conducted in Napa and Sonoma Counties acknowledges the presence of EDCs.

Those EIRs conclude, as did the North Sonoma County Agricultural Reuse Project EIR:  “it is not currently possible, using existing standards and/or regulatory agency risk assessment methodology, to evaluate the endocrine effects of these chemicals, if any, at the low concentrations reported.”

Carnegie Mellon chemicals may break down water contaminants safely

From Science Codex

"PITTSBURGH—A family of molecules developed at Carnegie Mellon University to break down pollutants in water is one step closer to commercial use. Study results published online in the journal Green Chemistry show that the molecules, which are aimed at removing hazardous endocrine disruptors from water sources, aren't endocrine disruptors themselves as they proved to be non-toxic to developing zebrafish embryos.

 "Created by Carnegie Mellon green chemist Terry Collins, the molecules, called TAML activators, provide an environmentally friendly method for breaking down toxic compounds that contaminate water, including endocrine disruptors. Endocrine disrupters, which are found in almost 25 percent of our streams, rivers and lakes, can disrupt the normal functions of the endocrine system by mimicking or blocking the activities of hormones in wildlife leading to impaired development.

"While the connections between the adverse effects of endocrine disrupting water contaminants on aquatic organisms and human health have yet to be established, animal studies suggest that endocrine disruptors may be involved in a host of modern-day health epidemics including cancers, learning disabilities, obesity, and immune and reproductive system disorders."

Read the rest of the article in Science Codex

BPA In Your Body

BPA has been a frequent topic in the news in recent years, because it’s an endocrine-disrupting chemical -- a compound that can imitate or disrupt the natural chemical regulators in your body such as those that control insulin and sex hormones. Disrupting hormones will affect your health.

By Becca Yeamans

Bisphenol A (BPA) is a chemical used in the production process of many plastic water bottles,  food containers, as well as liners of food cans and the coating on thermal paper cash register tape. 

BPA has been a frequent topic in the news in recent years, as it was discovered not too long ago that it’s an endocrine-disrupting chemical, which can wreak havoc on the environment and cause many public health problems.

AS POWERFUL AS NATURAL HORMONES

It was originally thought that BPA was a relatively weak estrogenic compound, though studies have recently suggested that BPA is just as strong an estrogenic compound than natural hormones like estradiol. 

 In other words, what was thought of as being relatively benign, BPA can actually cause significant problems at the levels currently present in the environment.

EXPOSURE FROM FOOD AND BEVERAGES

 Often times, humans are exposed to BPA by consuming food or beverages out of plastic containers that have been treated with the compound.   The levels of BPA ingested are particularly high when the plastic container has been heated in one way or another (i.e. by a microwave). 

PLASTIC WATER PIPES ARE A SIGNIFICANT SOURCE

A significant number of people can be exposed to BPA through the water supply.  At some point during the water treatment process, the water travels through PVC piping, the plastic of which is treated with BPA.   In fact, many homes have water pipes plumbed with PVC -- identifiable by its white plastic nature.

As water travels through these pipes laden with BPA, it picks up the chemical and carries it to homes and businesses.  In human, ingesting BPA has been associated with the development of diabetes, asthma, ovarian dysfunction, and obesity, and only in July of 2012 was this substance banned from baby bottles and drinking containers.

NOT LONG-LIVED IN THE NATURAL ENVIRONMENT

While research indicates that BPA can have serious effects once it's inside the human body, it actually doesn’t live for long in the environment. 

Once it hits the environment, it’s quickly broken down by microorganisms, resulting in a half-life of only 2.5 to 4 days.

HOW CAN SHORT-LIVED BPA BE A PROBLEM?

If BPA has such a short half-life, then how can it still exist in the environment and cause problems?

 In essence, while a single molecule of BPA is broken down relatively quickly, the fact remains that since BPA is present in so many man-made products and in the pipes carrying our drinking water, new molecules of BPA are continually added to the system. 

While BPA is present in the environment, it’s not known whether derivatives of this chemical have the same negative consequences as the original chemical, or if reactions with other chemicals in the environment somehow either inactivate or further worsen these effects.