Could be fatal (Image: Miguel Villagran/Getty)

DEATHS in US police custody during the early 1990s may have been the result of an interaction between capsaicin, the key ingredient in pepper sprays, and psychostimulant drugs, an experiment in mice suggests.

If the two have a fatal interaction in people then police forces might have to rethink their use of pepper spray as a non-lethal weapon, says John Mendelson of the Addiction and Pharmacology Research Laboratory at St Luke’s Hospital in San Francisco, who led the mouse research.

In the early nineties, anecdotal reports emerged in the US of people dying after …