Pyrethrins

Touted as safe by exterminators and sold widely in supermarkets and hardware stores for use at home, synthetic pyrethroids are used to kill ants, roaches, and mosquitoes. Based on the good safety record of chrysanthemum derived pyrethrins human neurotoxicity was practically unknown. Thus neurobehavioral symptoms and impairment were not anticipated in flight attendants who sprayed these agents repeatedly on airliners before landing in Auckland, New Zealand, and Sidney, Australia. Patients sprayed at home to saturation levels, to produce indoor residues and protracted effects, resembled the current practice to spray airliners to ensure pesticide residuals. Neurobehavioral examinations of 30 additional flight attendants confirmed the findings in the first three and from spraying with pyrethroids at home. Flight attendants frequency of 35 symptoms was greatly elevated, most had multiple symptoms triggered by other chemicals causing disability and seven (20%) had substantial impairment. In China pyrethrin toxicity has been studied in almost 600 people. These observations need to be confirmed but suggest that it is unrealistic to expect any pesticide to be safe for human brains.