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Garbage bins containing separated
organic leftovers such as banana skins, potato peelings and apple cores
release far higher numbers of potentially harmful bacteria and molds into
the kitchen than those containing mixed garbage, Dutch researchers have
found.
Netherlands researchers say
that the contaminants include bacteria and molds known to aggravate common
respiratory ailments, such as asthma. Millions could be at risk when they
dutifully segregate organic materials from their household waste for collection
and recycling as compost.
Researchers made the discovery
after collecting and analyzing household dust from 99 Dutch households,
some with segregated and some with mixed waste. They decided to carry
out the study after complaints from people when segregation was introduced
in the Netherlands six years ago. There were loads of complaints about
the smell from organic bins, and some people with respiratory illnesses
said their symptoms got worse. The reason is that the humid state of pure
organic waste suits microorganisms better than mixed waste, which "dilutes"
the organic material.
The team tested for cell fragments
called endotoxins, which are released when bacteria die. Their levels
reflect concentrations of bacteria in the dust. If exposure to these is
high enough, the endotoxins themselves cause coughing, breathlessness
and some flu-like symptoms. To detect molds, researchers screened dust
for beta-glucans -- sugars found in the coatings of numerous fungi. Beta-glucans
have been shown to cause lung and throat inflammation. The team also screened
for exopolysaccharides, polymers found in the cell wall of common Aspergillus
and Penicillium molds.
In homes where organic bins
regularly remained unemptied for a week or more, levels of the bacterial
endotoxins were three times as high as in homes with unseparated waste.
Levels of the mould materials, exopolysaccharides and glucans, were even
higher, some up to eight and five times as high respectively compared
with households that mix their waste. In houses with dust-accumulating
textile floors, as well as an organic waste bin, concentrations of the
microbial agents were higher still -- anything from 25 to 840 times as high
as in houses with neither risk factor.
The solution is to keep the
organic waste bin outside, but in many cases that's not possible in downtown
areas, where there's less space. The other remedy is to empty the bin
more regularly into the larger, roadside receptacles provided by the authorities.
Applied
and Environmental Technology (vol 66, p 627) March 2000
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