Sludge Watch ==> More on Nanotech issues - Tiny silver particules in clothing - sludge pollution

[Maureen Reilly]

http://www.sacbee.com/101/story/841669.html

Tiny silver particles in clothing may lead to pollution, research suggests

By Carrie Peyton Dahlberg - cpeytondahlberg at sacbee.com
Monday, April 7, 2008




In the unknowns of emerging nanotechnology, researchers are wondering if the 
science behind trendy no-smell socks, underwear and hunting gear might 
create unintended consequences in the environment.

Just a few simulated washings, for example, can pull nanosilver out of new 
socks that rely on it for killing odors, researchers said Sunday. That 
action sets the substance free to travel into wastewater and perhaps into 
fertilizer.

That prospect underscores the importance of studying nanosized materials 
that are increasingly a part of clothing and medical, electronic, and other 
consumer products, said UC Davis professor Alexandra Navrotsky.

"As a society, we should be doing research on these effects ideally before 
products go to market, not after," said Navrotsky, who heads a campus 
nanomaterials research unit.
University of California, Davis, is competing for a five-year, $25 million 
National Science Foundation grant to create a center devoted to studying the 
environmental impacts of nanomaterials, so small they are measured in 
billionths of a meter.

The campus, which survived the first cut when 30 grant applicants where 
whittled to 10, could learn later this month whether it is among three 
semifinalists.

At nanoscale, the nature of things can change fundamentally; items can take 
on different shapes, colors, electrical charges – or toxicities.

UC Davis researchers want to explore what happens when such creations are 
released into the environment, and nanosilver is on the short list of 
substances the university would target first if it wins the grant, Navrotsky 
said.

In one study with mouse sperm stem cells, nanosilver was about 45 times more 
toxic than standard silver, said Jennifer Sass, a toxicologist with the 
Natural Resources Defense Council in Washington, D.C.

Nanosilver is more potent because, in proportion to its size, it has more 
surface area where chemical reactions can take place.

"There's more killing activity per less volume," Sass said.

For human health, though, she worries about cosmetics and lotions with 
nano-ingredients much more than the clothing that has incorporated 
scent-controlling nanosilver.

"Silver is not the most toxic thing to humans," Sass said. "If you're a 
microbe, you have to worry a lot about silver, and that goes to beneficial 
microbes on our skin that eat up dead cells and dead hair."

The fear is that once it is washed out of socks or other clothing, 
nanosilver might keep on killing, taking out beneficial microbes in soil, 
groundwater or streams.

"The reason it's in socks is it kills bacteria," said Troy Benn, an Arizona 
State University doctoral student who outlined his findings Sunday at the 
American Chemical Society's national conference in New Orleans.

Sock studies being done by Benn and professor Paul Westerhoff at Arizona 
State University are "going to be really helpful," Sass said, because some 
people have suggested nanosilver wouldn't wash out of clothing.

Andrew Maynard, who tracks emerging nanotech for the Woodrow Wilson 
International Center for Scholars, said the work sounded like "a very useful 
piece of research."

The Arizona State research appears to be the first effort to measure how 
much silver comes out in the wash and to simulate what might happen to it 
during wastewater treatment, both Maynard and Sass said.

Benn collected his research material by shopping online for socks whose 
makers claimed they contained nanosilver. He chose seven different types 
made by five companies.

Researchers soaked and sloshed the socks in distilled water for up to seven 
simulated washings and found big variations from brand to brand when they 
tested the water.

One sock released more than a milligram of silver after a few washings, in 
the form of both nanosilver and one of its better-understood relatives, 
ionic silver. Some released much less, and at least one sock left no silver 
at all in the water.

That might not be surprising, though, since Benn did other tests – breaking 
down a sock with acid and analyzing what was left behind – to establish that 
one "nanosilver" sock contained no silver when it reached his lab.

It's possible the material simply sloughed off during shipping and handling, 
he said in an interview before the conference, or it might never have been 
there at all.

The research, which is ongoing and hasn't been published, didn't stop with 
the wash.

Westerhoff and Benn then "spiked" the wash water with activated sludge from 
a wastewater treatment plant, in an attempt to roughly simulate what might 
happen next.

Almost all the silver settled into a clumpy mass of "biosolids," separated 
from liquid effluent during treatment.

More than half of the biosolids produced by California water treatment 
plants are spread as fertilizer, which can interact with soil microbes and 
runoff.

About the writer:
Call The Bee's Carrie Peyton Dahlberg, (916) 321-1086.
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WERF - NANOPARTICLES IN SLUDGE ON LIST FOR STUDY

http://www.weftec.org/NR/rdonlyres/072B5D76-3159-44A6-BE6B-DB059BE0ECA2/0/Session118.pdf

Microconstituents: Occurrence in Biosolids and Air, Nanoparticles, Source 
Control, and Health Effects
Room 3
Moderator: Jay Witherspoon

Assistant Moderator: Joe Cleary

1:30 Occurrence of Microconstituents in Biosolids
T.O. Williams

2:00 Microconstituents of Concern Source Control Update: Unused 
Pharmaceutical Product Collection Programs
B.J. Koltz

2:30 Nanoparticles as Compounds of Potential Concern – A Technical Paper 
Update (TPU) for Water Environment Federation
G. Rajagopalan, A. Gu, K. Sellers, C. Mackay, D. Bouchard, I. Linkov
Networking Break