POPs in the snow
Canadian scientists have established that accumulation
of organochlorines in snow on mountains in temperate regions increases with
altitude.
The new findings demonstrate these areas tend to receive high
levels of precipitation and while being close to pollutant sources, are
particularly susceptible to the accumulation of semivolatile organochlorine
compounds.
Analysis of snow taken from coastal ranges and the Rocky
Mountains in south western Canada showed the concentration of organochlorines
increased 10 to 100 times between altitudes of 750 to 3,100 metres. The higher
levels are due to a process called 'cold condensation' which enhances the
deposition on these chemicals.
Organochlorines found during the analysis were chlordane,
dieldrin, endosulfan, heptachlor epoxide, hexachlorocyclohexane (including the
gamma isomer), and two types of (non-pesticide) bichlorinated biphenyls and
trichlorinated biphenyls (PCBs).
Nature, Vol. 395, No. 6702, p.585-588, 8
October 1998.
Bt threat to humans?
The bacterium Bacillus thuringiensis (Bt) has
been used to control a wide range of crop insect pests over the years. But now
microbiologists in France have treated a soldier who developed a serious wound
infection caused by Bt.
Doctors at the Military Hospital in Saint-Mande, near Paris,
examined the wounds of a soldier injured in 1995 by a mine at Sarajevo, Bosnia.
Initially, the bacterium infecting his wounds was identified
as Bacillus cereus, but unusual crystals, produced by the bacteria
prompted the medical team to have the strain rechecked.
Laboratories at the World Health Organisation Pasteur
Institute in Paris independently identified the sample as Bt. Later French
microbiologists confirmed that commercial strains of Bt could also infect wounds
in laboratory mice.
Nevertheless, companies marketing Bt still think it is not a
hazard to operators as there has been a long history of safe use that goes back
to the mid 1960s.
New Scientist, 30 May 1998.
[This
article first appeared in Pesticides News No. 42,
December 1998, page 15]