Pesticide Exposure and Neurodevelopmental Outcomes: Review of the Epidemiologic and Animal Studies

Abstract

Assessment of whether pesticide exposure is associated with neurodevelopmental outcomes in children can best be addressed with a systematic review of both the human and animal peer-reviewed literature. This review analyzed epidemiologic studies testing the hypothesis that exposure to pesticides during pregnancy and/or early childhood is associated with neurodevelopmental outcomes in children. Studies that directly queried pesticide exposure (e.g., via questionnaire or interview) or measured pesticide or metabolite levels in biological specimens from study participants (e.g., blood, urine, etc.) or their immediate environment (e.g., personal air monitoring, home dust samples, etc.) were eligible for inclusion. Consistency, strength of association, and dose response were key elements of the framework utilized for evaluating epidemiologic studies. As a whole, the epidemiologic studies did not strongly implicate any particular pesticide as being causally related to adverse neurodevelopmental outcomes in infants and children. A few associations were unique for a health outcome and specific pesticide, and alternative hypotheses could not be ruled out. Our survey of the in vivo peer-reviewed published mammalian literature focused on effects of the specific active ingredient of pesticides on functional neurodevelopmental endpoints (i.e., behavior, neuropharmacology and neuropathology). In most cases, effects were noted at dose levels within the same order of magnitude or higher compared to the point of departure used for chronic risk assessments in the United States. Thus, although the published animal studies may have characterized potential neurodevelopmental outcomes using endpoints not required by guideline studies, the effects were generally observed at or above effect levels measured in repeated-dose toxicology studies submitted to the U.S. Environmental Protection Agency (EPA). Suggestions for improved exposure assessment in epidemiology studies and more effective and tiered approaches in animal testing are discussed.

Survey of pyrethroid, macrocyclic lactone and antibacterial residues in bulk milk tank from Minas Gerais State, Brazil

“…On the other hand, the application of some veterinary drugs used on dairy farms can be a source of widespread and persistent environment contami-nation that can remain in the soil or water for a period of over 20 years (Gassner et al 1997, Zuccato et al 2000, Iftikhar et al 2014. Highlighting the data found on pesticide residues in raw milk, pyrethroid compounds are toxic and can accumulate in an organism causing severe neurological (Burns et al 2013) and respiratory symptoms (Hudson et al 2014), as well as, can adversely affect endocrine and immune systems (Du et al 2010, Costa et al 2013). a Set by Brazilian Maximum Residue Levels.…”

The Red Blood Cell Acetylcholinesterase Levels of Depressive Patients with Suicidal Behavior in an Agricultural Area

“…Hippocampus is a structure with important roles in depression, suicidal events, memory and imagination [34]. Animal studies demonstrate that OPs inhibit AChE levels in the brain and produce such effects as keeping serotonin concentration levels low and targeting various neurochemical factors such as growth factors, various neurotransmitters and secondary messengers [35,36]. Nevertheless, AChE inhibition is a sign of exposure to OPs, other neurotoxic mechanisms may exist also.…”

Reference compounds for alternative test methods to indicate developmental neurotoxicity (DNT) potential of chemicals: Example lists and criteria for their selection and use_suppl

“…However, complete weight-of-evidence evaluations are lacking for most compounds. For example, there is still controversy in the field as to the relevance of DNT effects of chlorpyrifos at human exposure levels (Burns et al, 2013;Li et al, 2012;Mount et al, 2009).…”