Pyrethroids are a group of synthetic chemicals which are used as pesticides in a variety of commercial, agricultural, and home uses. The chemical is synthesized from a plant, derived from the chrysanthemum plant and is just as toxic as other pesticides. Permethrin is also used for insect control on agricultural crops, particularly fruits and vegetables.
The use of pyrethroids is rapidly increasing due to the concern associated with toxic exposure to organophosphates. Organophosphate and pyrethroid pesticides interfere with the function of the nervous system of insects, and to a lesser degree with that of mammals, again raising concerns for human health in particular for children. Pesticide residues on food are currently the the major source of exposure and inhalation, dermal exposure, and non-intentional ingestion also may be important exposure routes for pesticides.
The Environmental Protection Agency recognizes that children are at greatest risk from pesticide toxicity because the developing brain is more susceptible to neurotoxicants, and they interact with their environment in a more hands on approach such as frequent hand-to-mouth behavior and outside play. Children have higher levels of cumulative internal exposure than adults for a given level of environmental exposure because of lower body weight, and because their detoxification mechanism for pesticides is not fully developed.Children are at a greater risk for some pesticides for a number of reasons. Children’s internal organs are still developing and maturing and their enzymatic, metabolic, and immune systems may provide less natural protection than those of an adult. There are “critical periods” in human development when exposure to a toxin can permanently alter the way an individual’s biological system operates. Children may be exposed more to certain pesticides because often they eat different foods than adults. Children typically consume larger quantities of milk, applesauce, and orange juice per pound of body weight than do adults.
Prior studies have linked exposure of organophosphate pesticides during pregnancy to increased psycho-motor and mental development delays, attention problems, attention deficit/hyperactivity disorder (ADHD)–like problems, and symptoms consistent with pervasive developmental disorder and negatively associated with IQ scores.
Exposure to organophosphate pesticides after birth has been associated with parent-reported problems with motor skills and behavior, poorer short-term memory and attention, slower motor speed, longer reaction time, and ADHD in children.
Results from a Canadian study conclusively demonstrated that pyrethroid exposure in children leads to similar problems although the researchers suggested that a more in depth study to deal with the study limitations was required.
The study demonstrated that living in a household where pesticides were used to treat pets or head lice was significantly associated with a high score on the dimension scale for emotional symptoms in children. In addition, the use of pesticides for any purpose in the previous month was positively associated with high scores on the dimension scale for conduct problems. A 10 fold increase in the detection of a pyrethoid metabolite, cis-DCCA, in a child’s urine was associated with a doubling in the odds of having a high level of parent-reported behavioral problems.
A prior study demonstrated the neurotoxic impact of pyrethoid compounds with findings confirming that dopaminergic neurotransmission is affected by exposure to pyrethroid and organophosphorus insecticides, and may contribute to the overall spectrum of neurotoxicity caused by these compounds. A more in-depth study evaluating the exact pathway in children in required.
Youssef Oulhote and Maryse F. Bouchard. Urinary Metabolites of Organophosphate and Pyrethroid Pesticides and Behavioral Problems in Canadian Children. Environ Health Perspect. 2013 Nov-Dec; 121(11-12): 1378–1384.
Soderlund DM, Clark JM, Sheets LP, Mullin LS, Piccirillo VJ, Sargent D, Stevens JT, Weiner ML. Department of Entomology, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, USA. Mechanisms of pyrethroid neurotoxicity: implications for cumulative risk assessment.Toxicology 2002 Feb 1;171(1):3-59
Schulze M, Helber B, Hardt J, Ehret W. Umweltmedizinisches Zentrum (Direktor: Prof. Dr. Dr. W. Ehret), Klinikum, Augsburg.
[Pyrethroid exposure following indoor treatments with a dog flea powder] Dtsch Med Wochenschr 2002 Mar 22;127(12):616-8
Karen DJ, Li W, Harp PR, Gillette JS, Bloomquis JR. Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA. Striatal dopaminergic pathways as a target for the insecticides permethrin and chlorpyrifos. Neurotoxicology 2001 Dec;22(6):811-7