From Halvard Baugerød, Agricultural University of Norway, Tarnbygningen, Norway
Please inform John Emsley that the deaths which occurred after consumption of rhubarb leaves (New Scientist, Science, 5 November) were probably not caused by oxalic acid. According to E. Streicher (Deutsche medizinische Wochenschrift, vol 89, 1964), it is the antrachinones (total content 0.5 to 1.0 per cent) in young rhubarb leaves which is responsible for the toxic effects. So your heading and picture caption seem unduly alarmist.
Table salt can also be toxic.
