~dGossip
~tPerinatal Bisphenol-A Exposure May Affect Fertility
~w2010-12-15
According to a recently published study, exposure to a ubiquitous
environmental chemical during pregnancy may impair reproductive
capacity of female offspring. The new study, published in the journal
Environmental Health Perspectives, found that fertility decreased
over time in female mice that had been exposed to doses of bisphenolA (BPA) that were lower than or equal to human environmental exposure
levels during foetal and neonatal (perinatal) development. "Mice
exposed to BPA in the womb and during nursing subsequently had fewer
successful pregnancies and delivered fewer pups over the course of
the study," reported one of the study's co-senior authors, Ana M.
Soto, MD, professor of anatomy and cellular biology at Tufts
University School of Medicine (TUSM) and member of the cell,
molecular and developmental biology program faculty at the Sackler
School of Graduate Biomedical Sciences. At the highest of three doses
tested, only 60% of the BPA-exposed mice had four or more deliveries
over a 32-week period, compared with 95% in the unexposed control
group. Decline of the reproductive capacity of the female mice in
this study was not obvious at first pregnancy, when the animals were
very young, but manifested later in life with a decline in number of
pups born per delivery. "This finding is important because standard
tests of reproductive toxicology currently consist of assessing the
success of a first pregnancy in young animals. If subsequent
pregnancies are not examined, relevant effects may be missed," said
co-senior author Beverly S. Rubin, PhD, associate professor of
anatomy and cellular biology at TUSM and member of the cell,
molecular and developmental biology and neuroscience program
faculties at the Sackler School. "In addition, the infertility effect
of BPA was dose-specific in our study. The lowest and highest doses
we tested both impaired fertility, while the intermediate dose did
not. This phenomenon, called non-monotonicity, is a common
characteristic of hormone action. In other words, chemicals have to
be tested at a variety of doses in order to avoid false "no effect"
results," added co-senior author Carlos Sonnenschein, MD, professor
of anatomy and cellular biology at TUSM and member of the cell,
molecular and developmental biology program faculty at the Sackler
School.
"BPA has effects that mimic those of oestrogen, a natural hormone.
Foetal and neonatal exposure to BPA has been shown to have other
hormone-related effects in rodents, including increased risk of
mammary and prostate cancers, altered behaviour, and obesity. In
addition, BPA has been found in the urine of over 92% of Americans
tested, with higher levels in children and adolescents relative to
adults. It has also been detected in human maternal and foetal
plasma," said co-first author Perinaaz R. Wadia, PhD, a research
associate in the Soto/Sonnenschein laboratory at TUSM. "Our findings
are potentially of great relevance to humans because BPA is used in
the production of materials people are exposed to every day, such as
polycarbonate plastics and the resins used to coat the inside of food
and beverage cans," said co-first author Nicolas J. Cabaton, PhD,
formerly a post-doctoral fellow in the Soto/Sonnenschein laboratory
at TUSM and now at the French National Institute for Agricultural
Research (INRA). During the study, the researchers compared the
effects of BPA to those of diethylstilbestrol (DES); a hormonally
active chemical that is known to have caused reproductive impairment
in women exposed during foetal life, and concluded that the effects
of these two chemicals on fertility were comparable. Similar to BPA,
low doses of DES had failed to cause obvious reproductive problems
when evaluated only at first pregnancy as in the standard tests used
by regulatory agencies to determine toxicity. The three doses of BPA
tested are within the range of human exposure and below the
Environmental Protection Agency (EPA) reference dose (i.e., the
maximal acceptable daily dose). "Our results suggest that a more
sensitive test, like the one used in this report should be adopted by
regulatory agencies in order to uncover the true risk and possible
epigenetic effects of suspected endocrine disruptors," said Soto.
Science Daily, 2 December 2010
<a href="http://www.sciencedaily.com">http://www.sciencedaily.com</a>
~dGossip
~tSunscreen-melanoma mystery explored
~w2010-12-15
An Australian study appears to have answered the burning question at
the core of sun safety - can sunscreen actually help to prevent
melanoma? Despite evidence that sunscreen can protect against less
lethal forms of skin cancer, its effect on the incidence of rarer but
often deadly melanoma has remained unclear. Complicating the research
is the fact very fair-skinned people, who have the most cases of
melanoma, were most likely to heed the warning and so routinely slop
on their sunscreen. According to Adele Green, Professor of
Epidemiology at the Queensland Institute of Medical Research (QIMR),
"People who are at naturally higher risk of melanoma are also
naturally the people who use sunscreen," said. "You can imagine then,
this is very hard to disentangle whether there is a protective effect
of sunscreen on melanoma.”There can even be this confusing effect
where ... there's more melanoma among people who use sunscreen." So
while sunscreen has long been recommended as a "precaution" against
all skin cancers, the science on its effect on melanoma alone has
remained "highly controversial". This was the case until Professor
Green’s unique new study, which tracked a group of just over 1600
residents in Nambour, Queensland, and it showed how wearing sunscreen
every day cut their incidence of melanoma in half. The adults were
randomly allocated to either a control group - who continued as per
normal and wore as much or as little sunscreen as they liked - or a
group given an unlimited supply of sunscreen. Those provided with
free sunscreen were asked to apply it every morning to their head,
neck, arms and hands and the trial ran for five years to 1996.
Monitoring over the next 10 years identified 22 cases of melanoma in
the control group, and 11 cases among those who wore sunscreen every
day. Prof Green said while the result appeared to be conclusive it
was too early to declare the sunscreen-melanoma debate as over. "I
wouldn't say that on the strength of one study but this has to be
reassuring at this stage," she said. "... to medical professionals,
public health authorities and the general public, that the regular
application of sunscreen is likely to be beneficial with regard to
melanoma protection." There are three major types of skin cancer,
with melanoma the least common but most often lethal as the cancer
could can spread from its initial site on the skin to generate
tumours elsewhere in the body. The other types - basal cell carcinoma
or squamous cell carcinoma - were more regularly seen but were less
likely to spread and so were not usually life-threatening if detected
early. There are more than 10,000 cases of melanoma diagnosed every
year in Australia, which shares the world's highest incidence of
melanoma along with New Zealand. More than 430,000 Australians are
treated every year for non-melanoma skin cancer. The recent study was
published in the Journal of Clinical Oncology.
The Age, 7 December 2010
<a href="http://www.theage.com.au">http://www.theage.com.au</a>
~dGossip
~tOral contraceptives are not a major oestrogen source in drinking
water
~w2010-12-15
The contribution of oral contraceptives to oestrogen pollution in
water is relatively small compared to other agricultural, industrial
and household sources. A new study has discovered that oral
contraceptives are not the main culprit in oestrogenic pollution of
US and European rivers and drinking water. Instead, the contribution
of contraceptives is quite small compared to other human, industrial
and agricultural sources. There has been increasing concern about
oestrogenic pollution due to scientific studies that document the
feminisation of fish and other aquatic animals. Previous research has
suggested that long term exposure to low levels of oestrogens in
water may adversely affect human health. The findings from the new
study should ease concerns that contraceptives are a major factor
contributing to feminised fish and frogs. During the study, the
researchers reviewed scientific studies from Europe and the United
States to determine if OCs were to blame for oestrogen pollution.
They identified sources of oestrogens in surface, source and drinking
water and paid close attention to the main oestrogen in OCs, 17
alphaethinylestradiol (EE2). In addition, the researchers evaluated
the public health impact of oestrogenic pollution in drinking water.
The results demonstrated that agricultural sources are an important
source of oestrogens in waterways because livestock produce 13 times
more solid waste than humans. The animals can excrete both natural
and pharmaceutical hormones. One study estimates that up to 90
percent of total oestrogens in the environment could come from animal
waste. Furthermore, water is polluted with other human sources of
oestrogen chemicals, including natural hormones and other oestrogencontaining prescription drugs, such as hormone replacement therapy.
Additionally, industrial and agricultural sources not only discharge
oestrogens, but they also release other harmful chemicals, such as
pesticides, which can mimic oestrogen. These compounds add to the
overall estrogenic pollution of our water supplies. On a positive
note, many wastewater and drinking water treatment plants can remove
80 to 99 percent of the synthetic oestrogens. These treatments also
seem to be effective at removing natural oestrogens, too. However,
there is a downside. Natural and synthetic oestrogens and oestrogenlike compounds from agricultural sources – especially livestock –
commonly enter waterways without treatment. Future efforts to reduce
exposures may need to focus on reducing all types of oestrogens in
waterways.
Environmental Health News, 7 December 2010
<ahref="http://www.environmentalhealthnews.org/">http://www.environme
ntalhealthnews.org/</a>
~dGossip
~tSealants Are Source Of Lake Pollution
~w2010-12-15
A new study undertaken by researchers from the U.S Geological Survey
(USGS) has found that coal-tar-based pavement sealants are the
largest source of polyaromatic hydrocarbon (PAH) pollution in many
urban lakes. The National Toxicology Program classifies eight PAHs
found in coal tar as “reasonably anticipated to be human
carcinogens.” They are also toxic to aquatic organisms. During the
new study, published in the journal Science of the Total Environment,
USGS researchers analysed sediment cores from 40 U.S. lakes, then
determined the sources of PAHs. The results demonstrated that on
average, coal-tar-based sealants contributed approximately half of
the PAHs found. Another quarter came from spilled motor oil and
particles worn from tires. In addition, the study reported that
levels of PAHs were significantly higher in lakes of the eastern and
central U.S., where coal-tar-based sealants predominate the market.
Chemical & Engineering News, 13 December 2010
<a
href="http://pubs.acs.org/cen/news">http://pubs.acs.org/cen/news</a>
~dGossip
~tBacteria clean up metal waste, then serve as catalysts
~w2010-12-15
In a new study, a team of Danish researchers have developed a method
to recycle valuable metals that would ordinarily have to be mined and
refined before ending up in chemists’ hands. The new technology will
means that the metals could be sourced instead from electronic waste
or polluted water and soil. During the study, the researchers used
two species of bacteria and added hydrogen gas to recover the waste
metals – palladium, platinum and rhodium – in a cheaper and more
efficient way than conventional processes. Interest in using microbes
to remove metals from waste is growing among scientists who are
searching for the best methods. This is the first time that
researchers report that they can remove these platinum group metals
from industrially contaminated water without altering the bacteria or
diluting the liquid. Remarkably, the bacteria could remove up to 100
percent of the palladium from the polluted water. Mining, industrial
activities and manufacturing release these specific metals into the
environment, where they can contaminate soil and water. All three of
the metals examined are widely used in automotive, chemical, glass,
electrical, medical and jewellery applications. The microbes used in
the study are naturally tolerant of metals. One species can be found
in typical soils, and the other is more commonly found in industrial
areas, near mines and metal factories.
The bacteria bind and absorb metal ions dissolved in water. In
addition, hydrogen gas can remove metal from the water. Metal uptake
and recovery are enhanced when the two are combined. The contaminated
water used in the study contained a mixture of eight different metals
and was deep orange coloured. Hydrogen gas and bacteria with and
without added palladium were added to test tube samples. The liquid
cleared after 24 hours, indicating the metals had been removed. The
bacteria were most selective for palladium – the recovery rates were
96-100 percent, compared to 70-74 percent for platinum and 55-57
percent for rhodium. After recovering the bacteria, researchers asked
what could be done with the metal-rich material. They went a step
further and found a productive use. They showed that the microbes
could drive a common chemical reaction that uses palladium to connect
two hydrocarbon building blocks, a method often used in synthesising
pharmaceuticals. The conversion rates were 50-100 percent. The
effectiveness was higher when the bacteria were pre-treated with a
small amount of pure palladium before exposure to the wastewater. The
researchers will now undertake further testing in order to determine
how the metals compete for the absorption sites on the bacterial
surface, and thus, produce treatment methods that select for specific
metals. In turn, the selective, one-metal binding could result in
more active catalysts to be used in conventional processes.
Environmental Health News, 9 December 2010
<ahref="http://www.environmentalhealthnews.org/">http://www.environme
ntalhealthnews.org/</a>
~dGossip
~tCAS Report Reveals Growth in Nanofiltration
~w2010-12-15
According to Chemical Abstracts Service (CAS), a division of the
American Chemical Society, over the past 4 decades, water scarcity
has become a global concern and nanofiltration has grown faster than
other water purification methods including reverse osmosis and
chemical disinfection. In a new report, CAS reviewed journal
publications and patents and found that while the numbers of
publications about all types of filtration have increased,
nanofiltration has grown the most since its emergence in 1987.
Nanofiltration methods run water through a fine membrane to remove
small solutes such as oil and pesticides. CAS found that U.S. authors
penned more journal articles about nanofiltration than did scientists
from other countries and that more patents were filed in China than
elsewhere.
Chemical & Engineering News, 10 December 2010
<a
href="http://pubs.acs.org/cen/news">http://pubs.acs.org/cen/news</a>
~dGossip
~tFDA to re-examine metal dental fillings
~w2010-12-15
U.S. health regulators are seeking a second opinion on whether
mercury-containing dental fillings pose a risk to dental patients,
especially children and pregnant women. According to Food and Drug
Administration officials, while there are no new scientific findings
on such silver-coloured cavity fillings, it wants feedback on methods
it used to weigh available data and decide last year that the metal
alloy is safe. In documents released recently, the agency said it
would ask its panel of outside experts to assess how much mercury
dental patients are exposed to and how much exposure is acceptable.
In July 2009, the FDA declared the fillings, known as dental amalgam,
posed no risk. A year earlier, it had cautioned against their use in
certain more vulnerable people such as pregnant women and children,
noting mercury's risks. The agency is revisiting the issue after four
groups questioned its assessment and petitioned for a second look.
The panel of outside experts will consider available data as well as
the agency's interpretation before offering recommendations. "Based
on its own review and feedback from the panel, FDA will decide
whether to make changes to its regulation," Nancy Stade, deputy
director of policy for the FDA's device centre, said. "At this time,
the FDA is not modifying its existing recommendations to consumers."
Mercury is a known toxin, and at issue is whether the vapours
released from mercury in dental fillings are enough to cause harm
such as brain or kidney damage. While some experts and advocacy
groups say mounting data show a clear link between mercury and side
effects and that dental fillings are no exception, industry groups
and dentists say the evidence shows dental amalgam is safe. FDA could
decide to continue backing the metal fillings, again urge more
cautious use, or ban the products.
Any reversal could affect dental filling makers such as Dentsply
International Inc and Danaher Corp's Kerr unit, and distributors such
as Henry Schein Inc and Patterson Cos Inc. The American Dental
Association said recently, "there is no scientific reason to revisit"
FDA's 2009 ruling and that the data has not changed since then.
But various groups are planning to hold protests outside the meeting
and want such fillings banned. The controversial issue is also
expected to draw four hours of public comments during the two-day
meeting. "Amalgam is a primitive, polluting, pre-Civil War device
which no modern dentist uses," Charles Brown, the lawyer for the
Consumers for Dental Choice advocacy group, said. But, he added,
"we're actually pleases to see such serious questions" will be posed
to the FDA's panel. FDA released its questions to its advisers and
other documents on its website. While it now backs the fillings, FDA
has changed how it regulates them. Products must carry warnings
against use in poorly ventilated areas or in patients with mercury
allergies. Approximately 50 percent of an amalgam contains mercury,
while the rest is silver and other metals. Millions of Americans have
such lower-cost fillings to patch cavities in their teeth. Other
options include tooth-coloured composite resins, although there is
also some concern they can contain bisphenol A (BPA), a chemical used
in plastics that has raised unease.
Reuters Health, 13 December 2010
<a
href="http://www.reuters.com/news/health">http://www.reuters.com/news
/health</a>
~dGossip
~tThe Untapped Energy In Wastewater
~w2010-12-15
A new study by researchers in the U.K has suggested that instead of
consuming power to treat wastewater, municipalities should extract
the energy trapped in its organic molecules. The researchers reported
that the energy content of household wastewater is significantly
greater than previously thought. Wastewater, they report, contains
enough energy in each gallon to power a 100-W light bulb for five
minutes. Every year, the U.S. treats about 12.5 trillion gallons of
wastewater, a process that consumes about 1.5% of the nation's total
electricity. According to the new study, published in the journal
Environmental Science & Technology, instead of processing and dumping
wastewater, treatment facilities could convert wastewater's organic
molecules into fuels such as methane or hydrogen gas. Liz Heidrich, a
graduate student at Newcastle University said that they could even
generate power directly via microbial fuel cells, which use bacteria
that produce electricity as they consume molecules such as acetic
acid. Heidrich wondered how much energy was in the wastewater to
recover. In the literature, she found data on solid waste's energy
content, but discovered only one wastewater study, which estimated
about 6 kJ of energy per L of wastewater. She thought that the
calculation underestimated wastewater's total energy, because the
researchers may have evaporated important volatiles such as acetic
acid when they used an oven to extract organics from the wastewater.
So Heidrich and her colleagues turned to freeze-drying to conserve
more of the energy-rich compounds inside the wastewater. The process
was excruciatingly slow: Evaporating 2 L of wastewater—the amount
needed for a decent-sized dry sample—took over a month. Using a bomb
calorimeter to combust the freeze-dried solids, Heidrich found that
the wastewater her team had collected from a domestic wastewater
treatment plant in northeast England contained 7.6 kJ/L. The same
wastewater dried with an oven contained 5.6 kJ/L, about 26% less
energy than the freeze-dried sample. Yet, according to the
researchers, even freeze-drying may lose volatiles. They estimate
that the wastewater's actual energy content probably was closer to 10
kJ/L. The researchers would like to speed up their technique so that
other scientists could use it to measure a water sample's energy.
Until now, researchers have relied on chemical oxygen demand, a
simple calculation of the amount of organic chemicals in a sample
made by measuring the oxygen required to oxidise the compounds. But
Heidrich found that such measurements often didn't agree with the
energy content that she measured more directly. David Bagley, an
environmental engineer at the University of Wyoming who performed the
previous estimate, says the new study is well done and that its
figures provide even more incentive to develop technologies to
extract energy from wastewater. "We know it's worth the effort," he
says. "We should stop messing around and just go get that energy."
Chemical & Engineering News, 9 December 2010
<a
href="http://pubs.acs.org/cen/news">http://pubs.acs.org/cen/news</a>
~dGossip
~tCycling may have impact on sperm health: study
~w2010-12-15
Most exercise appears to have little relationship to either the
quality or quantity of sperm, but men who bike at least five hours a
week have fewer and less active sperm than men who didn't exercise, a
new study has suggested. Research among competitive athletes has
linked biking to genital or urinary problems and poor semen quality,
said Lauren Wise at Boston University, who led the study published in
the journal Fertility and Sterility. "However, we were uncertain
whether we would find an association among a sample of men engaged in
more moderate levels of physical activity," she said, warning it is
still too early to say regular biking caused the sperm problems.
Previous research has suggested that competitive athletes may have
issues with their sperm. However, the new study examined the
relationship between sperm health and exercise in 2,200 average men
attending fertility clinics. Each man provided a semen sample and
answered questions about their general health and physical activity.
After adjustment for the use of multivitamins, body weight, blood
pressure, choice of underwear and other variables, the authors found
that men who exercised regularly -- even vigorously -- were no more
likely to have problems with the quality or quantity of their sperm
than men who never exercised. However, when Wise and her colleagues
investigated specific types of exercise, they saw that men who said
they spent at least five hours per week biking were twice as likely
to have both a low sperm count and relatively poor sperm mobility.
Among men who did not get regular exercise, 23 percent had low sperm
counts -- but so did more than 31 percent of those who biked at least
five hours per week. Nearly 40 percent of frequent bikers had low
numbers of sperm with good motility, versus 27 percent of men who
didn't exercise.
Trauma or temperature increases in the scrotum may explain the
relationship between biking and semen health, Wise said. In addition,
the researchers noted that it was possible that the men included in
the study may not be representative of the general population, since
they were all attending a fertility clinic and therefore more likely
to have problems with their sperm. "More studies are needed to
replicate our findings before they can be considered causal," she
said.
Reuters Health, 9 December 2010
<a
href="http://www.reuters.com/news/health">http://www.reuters.com/news
/health</a>
~dGossip
~tArsenic Bacteria Breed Backlash
~w2010-12-15
The recent high-profile announcement about a bacterium that thrives
on arsenic is drawing criticism from scientists in multiple fields,
including chemists. The study claims that the microbe can swap
phosphorus for arsenic in its biomolecules, including DNA. But
outside experts say the data presented don't back this claim. NASA
astrobiologist Felisa Wolfe-Simon and her colleagues have been the
subject of worldwide media attention since they described a microbe,
scooped out of California's briny, arsenic-rich Mono Lake, which can
grow under conditions nearly devoid of phosphorus, one of six
elements common to all life on Earth. In the days since the story
broke, various scientists including University of British Columbia
microbiologist Rosemary J. Redfield have posted critiques of the work
online. Among several concerns, Redfield says, is that the team
didn't rigorously purify DNA samples "when it counted"; that is, when
checking for arsenic content. She plans to submit a formal letter to
the journal Science about the work. "My research team and I are aware
that our peer-reviewed Science article has generated some technical
questions and challenges from within the scientific community,"
Wolfe-Simon says in a statement. "Our manuscript was thoroughly
reviewed and accepted for publication by Science; we presented our
data and results and drew our conclusions based on what we showed.
But we welcome lively debate since we recognise that scholarly
discourse moves science forward," she adds. "We invite others to read
the paper and submit any responses to Science for review so that we
can officially respond." Indeed, the team's case for arsenic becoming
part of the microbe's DNA is not airtight because it depends on
studies that, even when taken together, don't provide all the
evidence they need, experts say. Nanosecondary ion mass spectrometry
(NanoSIMS) and inductively coupled plasma mass spectrometry, two of
the techniques the team employed, are useful for measuring the
relative concentrations of arsenic in microbial cells grown under
various conditions, says Nicholas Winograd, a SIMS expert at
Pennsylvania State University. NanoSIMS allowed the researchers to
take mass spectra at different points, in effect to take an MS
picture of the cell, Winograd says. "They've produced some solid
analytical data," he says. But the way both types of MS experiments
were run, "they break everything to pieces," he says. The team can
detect arsenic's presence in cells, "but they don't know what the
chemical environment of the arsenic is." To learn more about
arsenic's chemical environment, the team performed X-ray studies.
Extended X-ray absorption fine structure (EXAFS) spectroscopy, one
technique the team used, can reveal arsenic's oxidation state and
average distances of any bonds it's making, explains Keith O. Hodgson
at Stanford University, an expert on X-ray techniques. In its report,
the team "looks at the average distances, they make comparisons, and
they conclude that it's a reasonable assumption that arsenic could be
part of a DNA backbone," Hodgson says. However, "there's no direct
proof in the X-ray absorption data that the arsenic is a part of the
DNA backbone." The team "has not conclusively proven, in my view,
that arsenic has been incorporated into DNA," Hodgson says. It'll
take studies on isolated molecules with techniques such as X-ray
crystallography or NMR to unambiguously prove that, he says.
In addition, the researchers used a technique called X-ray
fluorescence (XRF), which exposes a sample to an intense and highly
focused beam of X-rays and then measures how atoms in that sample
discharge the energy input by fluorescence emission in the X-ray
wavelength range, explains Laszlo Vincze, an XRF expert at Ghent
University, in Belgium. XRF provides information about which chemical
elements are present in a sample and in what concentration. "XRF
alone cannot be used to determine the specific location of an element
in a given molecule structure," Vincze says. Combined with EXAFS, XRF
can only demonstrate that arsenic is in an environment consistent
with the idea that arsenic is in DNA but cannot provide indisputable
proof, he adds. "The evidence in the paper does not establish arsenoDNA," says Steven A. Benner, an expert in nucleotide chemistry at the
Foundation for Applied Molecular Evolution, in Florida. Esters made
with arsenic, as would have to appear in DNA, spontaneously fall
apart in water with half-lives on the order of minutes, a huge
chemical challenge for any microbe to surmount, he notes. "On the
other hand, there is not an easy explanation for the data that are
present," Benner says. The work shouldn't be dismissed outright, but
more biochemical tests should be done, such as checking for
radioactivity in purified nucleic acids from microbes fed radioactive
arsenic, he says. Most likely, the team has discovered a bacterium
that aggressively detoxifies arsenic species and scavenges phosphate
from its surroundings to survive, says Gerald F. Joyce of Scripps
Research Institute, an expert in RNA and origin of life research.
"This is an amazing story about how life can adapt to extreme
conditions," he says. "We've been concerned that some conclusions
have been drawn based on claims not made in our paper," Wolfe-Simon
says. In response, Science is making the article freely available for
a two-week period, says Ginger Pinholster, director of the American
Association for the Advancement of Science's Office of Public
Programs. And at a 7 December lecture streamed on NASA's website, coauthor Ronald S. Oremland of the U.S. Geological Survey said the team
will freely provide their bacterial strain to researchers interested
in testing it. "It is a shame when a bright and enthusiastic
researcher like Felisa isn't better advised by her chemistry
colleagues," says John D. Sutherland, an organic chemist at the MRC
Laboratory of Molecular Biology in Cambridge, England, who has
written a letter to the editor of Chemical &Engineering News
critiquing the findings. "Such a dramatic claim makes rock-solid
characterisation absolutely mandatory."
Chemical & Engineering News, 8 December 2010
<a
href="http://pubs.acs.org/cen/news">http://pubs.acs.org/cen/news</a>
~dGossip
~tDo Noxious Neighbours Spread Disease?
~w2010-12-15
Invasive plants are known for disrupting the ecologic balance in
plant and animal communities. They also may play a role in the spread
of human diseases, according to a new study of ehrlichiosis and its
relationship to the noxious weed Amur honeysuckle (Lonicera maackii ).Ehrlichiosis is an emerging disease that occurs in people and other
animals. In people, one of the most prevalent culprits is the
bacterium Ehrlichia chaffeensis, which causes a form of the disease
known as human monocytic ehrlichiosis (HME). In addition, there has
been a few documented cases of HME caused by Ehrlichia ewingii. Both
bacteria are transmitted by the lone star tick (Amblyomma
americanum), a vector thought to feed primarily on the white-tailed
deer (Odocoileus virginianus). First reported in 1987, the number of
reported HME cases has risen steadily from about 100 in 1999 to 957
in 2008. The 10-fold increase likely is due to a combination of
increased incidence, better reporting, and possibly increased
exposure to lone star tick habitat through outdoor work and
recreation, says Erik Hofmeister, veterinary medical officer with the
U.S. Geological Survey (USGS) National Wildlife Health Centre. Amur
honeysuckle, first introduced into the United States and Canada from
eastern Asia in the 1800s, was widely used for landscaping, soil
erosion control, and wildlife habitat enhancement, but its tendency
to invade native settings was noticed as early as the 1920s. It
seldom is used any more, says Robert Schutzki, an associate professor
of horticulture at Michigan State University. Nonetheless, it’s well
established, often in urban and urban fringe areas, throughout much
of the eastern half of the United States and Ontario, Canada.
Noticing the overlapping geographic distribution of HME, lone star
ticks, their hosts, and Amur honeysuckle, Brian Allan, now an
assistant professor of entomology at the University of Illinois at
Urbana–Champaign, set out to investigate the relationship among these
four factors. During the study, the researchers assessed nine natural
areas in the St. Louis, Missouri, region, pairing honeysuckle-invaded
and uninvaded plots measuring at least 30 m2. They also compared
invaded plots against those where they removed honeysuckle (either
whole plants or just the fruit).
In both situations, they found a strong link between Ehrlichiainfected lone star ticks, deer, and Amur honeysuckle. Elaborating on
figures published in his paper, Allan says the density of E.
chaffeensis-infected tick nymphs in the honeysuckle stands was 25
times higher than in nearby stands of native vegetation, and deer
density was 4 times higher. In areas where honeysuckle was removed,
he says the density of E. ewingii-infected tick nymphs was 17 times
lower than in nearby stands of honeysuckle vegetation, and deer
density was 5 times lower. One other invasive plant (Japanese
barberry, Berberis thunbergii ), has been linked with an emerging
human illness (Lyme disease). Preliminary evidence indicates another
invasive plant, garlic mustard, also may play a role in Lyme disease,
says Felicia Keesing, an associate professor of biology at Bard
College. Allan says the new evidence suggests additional research on
links between invasive plants and human diseases is required.
Hofmeister is impressed with this study, including the in-depth
analysis of the ecology of the disease, and he thinks it can have
immediate applications. For instance, he says, “Homeowners could
potentially reduce their risk of ehrlichiosis if they cleared the
honeysuckle from around their property.” But Tom Stohlgren, a
research ecologist at the USGS’s Fort Collins Science Centre in
Colorado, is sceptical of the study’s importance, though not entirely
negative. “I think this is a tangential direction,” he says. “It’s
better to go after the disease source itself, such as long-term
increases in deer populations due to predator control, and increased
urbanisation into deer habitat. This study carries the argument
deeper than it may need to go. But it’s an interesting and important
link, and I don’t want to lose it.”
Environmental Health Perspectives, December 2010
<a href="http://ehponline.org">http://ehponline.org</a>
~dGossip
~tAsthma? Allergens Could Be Growing in Your Lungs
~w2010-12-15
New research into the allergic reactions that asthmatics suffer
towards a common mould has uncovered that many people with asthma
actually had the mould growing in their own lungs. The research led
by University of Leicester scientists at Glenfield Hospital has been
published in the December 2010 issue of the American Journal of
Respiratory and Critical Care Medicine. The team based in the
Institute for Lung Health at the University of Leicester and
Glenfield Hospital examined the impact on asthmatics of a common
environmental mould, Aspergillus fumigates, usually found in soil and
compost heaps. Professor Andy Wardlaw from the University of
Leicester said: "Asthma is a very common condition where the
breathing tubes (bronchi) can go into spasm making it difficult to
breathe. Around a fifth of adults with severe asthma, which they have
had for a long time, get permanent (fixed) narrowing of their
bronchi. It is known that A. fumigatus can grow in the lungs of some
people with asthma and mould allergy, which can cause severe lung
damage. "This problem is thought to only affect a very small number
of people with asthma; however, about half of people with severe
asthma have evidence of allergy to moulds like A. fumigatus."
Researchers in the Institute for Lung Health at the University of
Leicester and Glenfield Hospital, Leicester, carried out a study
funded by the Midlands Asthma and Allergy Research Association
(MAARA, a Midlands based charity funding research into asthma and
allergy research) and the European Regional Development Fund (ERDF),
to determine whether the problem of A. fumigatus growing in the lungs
is more common than previously thought, and whether this could
explain the fixed narrowing of the airways that occurs in some people
with asthma. Professor Wardlaw added: "Our study showed that 6 out of
10 people with asthma who were allergic to A. fumigatus grew the
mould from their sputum. We also found that if you were allergic to
A. fumigatus you had more narrowing of the airways than if you were
not allergic, and this was worse in patients from whom A. fumigatus
was grown. "Our research concluded that it is possible that fixed
narrowing of breathing tubes in many people with asthma could be
caused by A. fumigatus growing in their lungs. "Treating individuals
from whom A. fumigatus is detected with antibiotics against the mould
may prevent fixed narrowing of the airways."
Science Daily, 14 December 2010
<a href="http://www.sciencedaily.com">http://www.sciencedaily.com</a>
~dGossip
~tTransformation of Silver Nanoparticles in Sewage Sludge
~w2010-12-15
The release and environmental fate of nanoparticles throughout the
life cycle of “nanoenabled” goods is an area of growing research
interest. In the first known field study of the fate of silver
nanoparticles in the wastewater treatment system, researchers now
report these nanoparticles transform into silver sulphide in the
sludge produced by sewage treatment plants. This new information
about the life cycle of silver nanoparticles provides a starting
point for further exploring their impact on the environment. Silver
has been used as an antimicrobial agent for millennia, and the
increased surface area offered by the nanoparticle form of the metal
offers greater germ-killing capacity. Manufacturers add silver
nanoparticles to hundreds of consumer products, including food
storage containers, clothing, computer keyboards, cosmetics, pillows,
cell phones, and medical appliances. Silver is water soluble, so
contact with any type of moisture—such as a bath or a spin in the
washing machine—washes some out and sends it into wastewater systems.
“We wanted to know what form of silver enters the environment after
it goes down the drain and passes through sewage treatment plants,”
says Michael Hochella, a geochemist at Virginia Polytechnic Institute
and State University and director of natural and incidental
nanoparticles for the multi-institute Centre for the Environmental
Implications of NanoTechnology. Sludge from sewage treatment
facilities can end up as landfill or soil amendments in agricultural
fertilisers, or it can be burned in incinerators. In 2006 and 2007
the U.S. Environmental Protection Agency (EPA) analysed sewage sludge
samples from 74 municipal wastewater treatment facilities nationwide
and tested for 28 metals, including silver (which was detected in all
the samples). Through the EPA, Hochella and postdoctoral fellow
Bojeong Kim obtained frozen samples of sludge from a Midwest
facility. They suspected it would contain the nanosilver particles
now used in consumer products—although the EPA’s goal in sampling was
simply to obtain national estimates of the concentrations of selected
analytes, not identify nanoparticles.
Kim developed analytical methods to determine the size, chemistry,
and atomic structure of silver nanoparticles in the samples. The
samples tested high in silver, but the silver could not be attributed
to an industrial source. Scanning transmission electron microscopy
revealed the nanoparticles were 5–20 nm in diameter and formed small,
loosely packed aggregates no more than 100 nm in size. Energydispersive X-ray spectrometry showed that sulphur (which is produced
by microorganisms that digest sewage) combined with the silver in a
2:1 ratio, and the crystal structure confirmed the formation of
silver sulphide nanoparticles. The results highlight the complexity
of environmental fate. “What we start with is not what ends up in the
environment,” Hochella says. The researchers don’t know how many
silver nanoparticles were introduced to the wastewater treatment
plants or how much incoming nanosilver ended up as silver sulphide
nanoparticles. However, Kim notes that no pure silver nanoparticles
were found in the sludge. In general, silver sulphide is highly
insoluble and settles out of water. But no one knows if silver
sulphide nanoparticles behave in the same way. Properties of metals
can change dramatically as particle size decreases. “It’s hard to
predict whether the solubility of nanoparticles will increase,
decrease, or stay the same,” Kim says. The bioavailability, toxicity,
and reactivity of silver sulphide nanoparticles also are unknown. If
silver sulphide nanoparticles do prove toxic, the environmental
implications could be unfavourable. Antimicrobial nanoparticles could
adversely impact desirable microorganisms that decompose waste in
sewage treatment plants, says Murray McBride, director of the Cornell
Waste Management Institute. Furthermore, McBride says, nanosized
silver sulphide applied to agricultural land could oxidise in soils
and release toxic silver ions that kill beneficial soil
microorganisms. On the other hand, one study of laboratory-grown
Pseudomonas putida biofilms indicated some bacteria bind silver ions,
potentially rendering them less toxic.
Environmental Health Perspectives, December 2010
<a href="http://ehponline.org">http://ehponline.org</a>
~dGossip
~tTobacco smoke causes immediate damage: U.S. report
~w2010-12-15
A new study by U.S federal officials has reported that cigarette
smoke causes immediate damage to a person's lungs and their DNA even
in small amounts, including from second-hand smoke. Taxes, bans and
treatment must all be pursued to bring smoking rates down, U.S.
Surgeon-General Dr. Regina Benjamin said. "The chemicals in tobacco
smoke reach your lungs quickly every time you inhale causing damage
immediately," she said in a statement. "Inhaling even the smallest
amount of tobacco smoke can also damage your DNA, which can lead to
cancer," she said. The report stated that tobacco companies
deliberately designed cigarettes and other tobacco products to be
addictive and that they released new products that are portrayed as
safer but that are in fact just as dangerous and addictive. Benjamin
said a third of people who ever try cigarettes become daily smokers
and Health and Human Services Secretary Kathleen Sebelius said
curbing smoking would remain a priority for President Barack Obama's
administration. Sebelius listed measures taken by Obama since he took
office two years ago, including "legislation to regulate tobacco
products, investing in local tobacco control efforts and expanding
access to insurance coverage for tobacco cessation." The Food and
Drug Administration has banned flavoured cigarettes and begun
investigating menthol cigarettes. In November it issued rules
requiring graphic images on cigarette packages. However, there have
been setbacks. An appeals court recently ruled that the FDA can only
regulate "e-cigarettes" -- or battery-powered products that allow
users to inhale nicotine vapour -- as tobacco products and not as
drugs, and thus cannot block their import. The report notes that
studies have shown cigarettes kill 443,000 people every year in the
United States -- one in every five people who die -- from cancer,
heart disease, lung disease and other causes. The Centres for Disease
Control and Prevention says efforts to reduce smoking have stalled in
recent years. Between 1998 and 2008, the number of smokers fell by
3.5 percent, from 24.1 percent to 20.6 percent. "The economic burden
of cigarette use includes more than $193 billion annually in health
care costs and loss of productivity," Sebelius said.
Reuters Health, 9 December 2010
<a
href="http://www.reuters.com/news/health">http://www.reuters.com/news
/health</a>
~dGossip
~tIncreased Consumption of Folic Acid Can Reduce Birth Defects but
May Also Be Associated With Colorectal Cancer
~w2010-12-15
Folic acid can reduce birth defects including neural tube defects,
congenital heart disease and oral clefts but a new study has
suggested that high intakes of folic acid may be associated with
adverse events such as colorectal cancer. The new study, published in
the Canadian Medical Association Journal, conducted by researchers at
Children's Hospital of Eastern Ontario Research Institute and The
Hospital for Sick Children, is the first of its kind in more than
three decades, to examine the folate status of Canadians including a
subset of women of childbearing age. During the new study, the
researchers investigated red blood cell folate concentrations in 5248
Canadians aged 6 to 79 years based on survey data representing around
96% of the Canadian population. After adjusting for age, sex and
socio-economic status, the study found that less than 1% of Canadians
showed folate deficiencies and 40% showed high folate concentrations.
However, in the subset of women of childbearing age, 22% were below
the concentration considered safe to guard against neural tube
defects. "Some medical practitioners argue that many women of
childbearing age need high-dose folic acid supplements and that
doubling the level of folic acid fortification in the food supply
should be considered," writes Cynthia Colapinto, CHEO Research
Institute, Healthy Active Living and Obesity Research Group, Ottawa,
Ontario and co-authors. "This argument has sparked considerable
debate because folic acid fortification targets women of childbearing
age by exposing the entire population to high levels of folic acid.
Given the absence of folate deficiency in the general population and
the apparent shift toward Canadians having high serum folate
concentrations, there appears to be little rationale for doubling
folic acid levels in the Canadian food supply. "Folate deficiency is
almost completely absent in the Canadian population, though high
folate concentrations exist. "Correction of folate deficiency and
improved folate status, in part through fortification, has been
associated with positive health outcomes such as the dramatic
reduction in neural tube defects," write the authors. "However, given
speculations about the possible adverse effects associated with high
levels of folic acid, including increased risk of certain cancers in
those with pre-existing neoplasms, further attempts to improve the
folate status of Canadian women of childbearing age by increasing
fortification levels should be approached cautiously." The authors
conclude that although folic acid is beneficial for women of
childbearing age, some people may have undesirable results so ongoing
monitoring of the folate status of Canadians and the relationship
between folic acid and health outcomes is needed.
Science Daily, 14 December 2010
<a href="http://www.sciencedaily.com">http://www.sciencedaily.com</a>
~dGossip
~tAccurate Method for Detecting Dangerous Levels of Fluoride
~w2010-12-15
Used in the proper amounts, fluoride can make teeth stronger and aid
in the treatment of osteoporosis. When excessive amounts are
consumed, however, it can be a killer -- a carcinogen that causes
bone, lung and bladder cancers. Fluoride is a common additive in most
American communities' drinking water and an ingredient in the vast
majority of commercially produced adult toothpastes. Determining the
level of fluoride, be it in water, consumer products or the human
body, is an important and attractive challenge for scientists. To
address that, a Florida State University researcher has developed a
molecular sensor that changes colour when a sample containing
fluoride is added to it. "The U.S. Environmental Protection Agency
recommends that 1 part per million (ppm) of fluoride ions is
acceptable in drinking water, but above 2 ppm is considered a serious
health risk," said Sourav Saha, an assistant professor in FSU's
Department of Chemistry and Biochemistry and its Integrative
NanoScience Institute. "Because fluoride is carcinogenic even at such
small doses, a sensor is needed to detect fluoride selectively at
very low concentrations and in the presence of other naturally
occurring and biologically important ions." Working with a team of
graduate students and postdoctoral researchers, Saha was able to
develop just such a sensor. His research team discovered that a
compound called naphthalene diimide (NDI) interacts with fluoride
ions in a uniquely colourful way. "NDIs are a family of neutral
(albeit electron-deficient) aromatic compounds that are colourless
until fluoride is added," Saha said. "A small amount of fluoride will
quickly turn the sample orange, while a larger amount will turn it
pink. In this manner, it becomes very easy to determine not only the
presence of fluoride in water, but at what levels."
While other fluoride sensors exist, many of them cannot differentiate
between fluoride and other anions -- negatively charged ions -- that
might be present in the water. "Although they can detect fluoride,
they cannot accurately measure the levels of fluoride," Saha said.
"Naked-eye detection of fluoride at different concentration levels is
an advantage of NDI-based sensors. Our sensor relies on an electron
transfer event from a fluoride ion to the NDI receptor for generating
a visible response or signal, which in this case is colour change.
The electron transfer process can be reversed, and the sensor can be
regenerated and reused over and over again." By designing an
appropriate sensor, Saha's laboratory has achieved a remarkable
"nanomolar" sensitivity for fluoride, meaning it can detect about one
ten-thousandth of a milligram of fluoride in a litre of water. This
makes it one of the most sensitive fluoride sensors known to date.
Water fluoridation has been widely used in the United States since
about 1960. Although often a subject of controversy, Saha says it has
had the effect of improving overall dental health through a very
basic chemical process. When added to water systems, fluoride reacts
with a naturally occurring mineral, calcium phosphate, and produces a
compound called fluorapatite. Fluorapatite then bonds with humans'
teeth to form a hard, protective layer that wards off corrosion. This
is important for dental health. However, excessive amounts of
fluoride in water can cause a condition known as dental fluorosis,
especially in young children. This results in a mottled appearance of
the dental enamel, as well as possible cracking and pitting of the
teeth. Furthermore, fluoride is used in several drugs prescribed to
treat the brittle-bone disease osteoporosis. Given in the proper
amounts, the fluoride appears to stimulate the formation of new bone
tissue. However, when excessive amounts of fluoride build up in body
tissues, they can lead to a variety of health maladies, including
skeletal fluorosis, which causes pain and damage to bones and joints.
Excessive fluoride over a length of time has also been linked to the
development of osteosarcoma -- a malignant and potentially fatal bone
cancer -- as well as cancers of the lungs and bladder. For those
reasons and others, fluoride has not been formally approved by the
Food and Drug Administration for the treatment of osteoporosis in the
United States.
Artificial fluoridation of drinking water is commonly practiced in
many industrialised nations. While precise numbers are unavailable,
perhaps 400 million people living outside of the United States are
located in areas where water is artificially fluoridated, according
to the British Fluoridation Society. Untold millions of others,
especially in parts of Africa, India and China, rely on water sources
whose natural fluoride levels exceed EPA recommendations. Efforts to
measure the amount of fluoride present in many of those areas are
inconsistent and imprecise. "This is a very significant public health
issue worldwide," Saha said. "Some developing countries fluoridate
their water but don't have a means for measuring it accurately.
Others are drinking water that hasn't been treated with fluoride but
that might already contain dangerous amounts naturally. Clearly there
is a critical need for a fluoride sensor that can tell people whether
their water supply is safe." In a report recently published in the
Journal of the American Chemical Society, his team describe their
findings. It was co-authored by Saha and his postdoctoral researcher,
Samit Guha. In addition, Saha filed for a U.S. patent on his
fluoride-sensing process in June 2010; he hopes to know within the
next year whether the patent will be granted. If it is, the next step
likely would be to license his discovery to an outside company that
could test it for commercial potential and then, if all goes well,
develop it into a marketable product. "This is a clever idea," said
John Fraser, Florida State's assistant vice president for Research
and Economic Development and director of the Office of Intellectual
Property Development and Commercialisation. "Using a simple colour
test to determine safe fluoride levels will lead to a tangible
benefit to society. Once commercialized, people will benefit in the
United States, but also in countries with high natural but unsafe
levels of fluoride."
Science Daily, 10 December 2010
<a href="http://www.sciencedaily.com">http://www.sciencedaily.com</a>