Chlorpyrifos is an insecticide belonging to the group of organophosphothioates. It is used in the culture of vegetables and in citrus orchards. Chlorpyrifos is an acetylcholinesterase inhibitor and as such having a highly toxic effect on the nervous system. There is evidence that chlorpyrifos has an effect on the foetus, which may lead to behavioural disorders.Chlorpyrifos-OVA conjugated can be used as a control to saturate anti-Chlorpyrifos antibodies.