Pyrethroids: Exposure and health effects, an update

Synthetic pyrethroids are present in numerous commercial insecticide formulations and have extensive worldwide indoor and outdoor applications, including agricultural, public, residential, and veterinary usages for pest control. Their use has continuously increased in recent years. This paper presents a review of the studies assessing human exposure and health effects of pyrethroids over the last decade. Their main metabolites have been frequently detected in urine samples from general populations, confirming widespread exposure of children and adults to one or more pyrethroids. Non-occupational exposure to pyrethroids mainly occurs through ingestion of residues in food, or ingestion or dermal contact with contaminated house dust or surface adhering particles, after domestic uses. Although clinical features resulting from acute accidental exposure to pyrethroids are well described (e.g. paraesthesiae, and respiratory, eye and skin irritation), information regarding their chronic effects at low concentrations is limited and controversial. Several recent epidemiological studies have raised concern about potentially adverse effects on sperm quality and sperm DNA, reproductive hormones, and pregnancy outcomes. Early neurobehavioural development after in utero exposure is more particularly discussed. Further research is needed for clarification.