ONE of the most bizarre scientific experiments to have been spawned by
the Cold War鈥攖he release of powdered zinc cadmium sulphide above the US to
simulate biological attacks鈥攑robably caused no human illnesses, says a
panel of the National Academy of Sciences.
On 33 separate occasions in the 1950s and 1960s, researchers released
powdered zinc cadmium sulphide into the atmosphere to see how it would be
dispersed under a variety of meteorological conditions. The powder was chosen
because its particles are about the same size as bacteria used in biological
weapons.
When details of the experiments were widely publicised several years ago,
they caused a furore. At the insistence of Congress, the US Army asked the
academy to find out whether anyone had been injured by the experiments. The
academy鈥檚 report, released last week, concludes that zinc cadmium sulphide is
probably harmless. Even if the compound were as carcinogenic as pure cadmium,
the report says that human exposure to the chemical was so low that there is no
cause for alarm. In St Louis, Missouri, which experienced the highest levels of
contamination, the rate of excess cancers among children living in areas where
the chemical fell most thickly would be only 1.2 per million people鈥攖oo
low to show up in health statistics.
Advertisement
The US Army restricted the study鈥檚 remit to health issues, so the thorny
question of whether the experiments were ethical is not addressed in the
report.
The experiments apparently revealed the most effective method for spreading
dangerous bacteria via biological weapons. But that method is still a military
secret. 鈥淭hat was the one piece of information the Army didn鈥檛 give us,鈥� says
Rogene Henderson of the Lovelace Respiratory Research Institute in Albuquerque,
New Mexico, who chaired the study.