Very effective as insecticides. Used since ancient times. Derived from flowers of chrysanthemums. Since frequently not fatal in insect, usually combined with more toxic, slower-acting poisons. Adverse effects 15g of a concentrate p.o. has killed adult human.
Death is due to respiratory failure.
Contact dermatitis is a common occurrence that may rarely extend to anaphylactic-type reaction. Massive oral doses may cause signs of CNS excitation, convulsion and paralysis. Allethrin - a synthetic pyrethroid may produce less dermatitis. These drugs act by slowing closure of the excitable membrane ion channels opened during action potentials so that there are multiple action potentials. The mixture contains CaS2, CaS5 and CaS2O3.