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Pesticide Exposure and Neurodevelopment in the Fetus


Exposure to pesticides has been linked to preterm birth and reduced fetal growth ... In utero exposure discovered that higher levels ... DDE exposure in utero ... – PowerPoint PPT presentation

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Title: Pesticide Exposure and Neurodevelopment in the Fetus

Pesticide Exposure and Neurodevelopment in the
  • Marcel Elizondo
  • July 2009 STEER Student
  • UTHSCSA-Harlingen

  • What is a pesticide?
  • According to the EPA, a pesticide is any
    substance or mixture of substances intended for
    preventing, destroying, repelling, or mitigating
    any pest
  • What about pests?
  • Pests are living organisms that occur where they
    are not wanted or that cause damage to crops or
    humans or other animals4

Looking at mosquito larvae at the City of
Brownsville lab
  • Some examples of pests include
  • Pests include mosquitoes, beetles, ants
  • How do pesticides kill pests?
  • Pesticides attack the nervous system of the pests
    which in turn leads to their untimely demise5

Elimination of Pesticide Use
  • Stockholm Convention on Persistent Organic
  • This agreement was signed by 90 countries in 2001
    to eliminate the use of 12 POPs including DDT
  • The World Health Organization made an exception
    in 2006 to back the use of DDT to control malaria
    in certain countries2

Pesticide Use
  • In the US, our agricultural areas use more than
    75 of conventional pesticides
  • Exposure to pesticides has been linked to preterm
    birth and reduced fetal growth
  • A popular pesticide used to be dichlorodiphenyltri
    chloroethane (DDT), which was subsequently banned
    in the US in the 70s
  • Currently, replacement pesticides for DDT are
    insecticides such as organophosphates.1

Effects of Some Pesticides
  • Organochlorines (i.e. DDT)
  • Excitation of central nervous system which leads
    to tremors, hyperexcitability and convulsions
    (both tonic and clonic)
  • Organophosphate (i.e. insecticides)
  • Act by inhibiting the acetylcholinesterase in
    synaptic clefts1

Inhibiting the Acetylcholinesterase
Inhibiting the Acetylcholinesterase
Organophosphate Detection
  • Exposure to organophosphates is usually measured
    by nonspecific metabolites in urine known as
    dialkyl phosphate (DAP) metabolites1

DO NOT offer your friends pesticides as a home
remedy for cough.
Human Studies
  • Center for the Health Assessment of Mothers and
    Children of Salinas (CHAMACOS)
  • Research is funded by NIH and EPA
  • Four objectives of CHAMACOS
  • Six hundred and one pregnant woman were recruited
    in 1999-2000. They were at least 18 years old
    and were less than 20 weeks in their gestation

  • Neonatal neurodevelopment was tested using the
    Brazelton Neonatal Behavioral Assessment Scales
  • Maternal serum samples of DDT and DDE were higher
    than the National Health and Nutrition
    Examination Survey reference population
  • A minor negative association was observed between
    maternal DDE serum levels and abnormal infant

  • Most other studies conducted had similar results
    to the CHAMACOS study
  • One exception was a study in North Carolina with
    a birth cohort of 912 infants
  • In utero exposure discovered that higher levels
    of DDE in the cord serum and breast milk led to
  • This exception is noted because a similar
    (although smaller) cohort in Oswego, NY was
    conducted and the North Carolina findings could
    not be replicated2

Spanish Study
  • Cohort of 92 children
  • Exposed to high levels of DDE
  • Had lower social, mental and psychomotor
    development (assessed using Griffiths Scales of
    Infant Development and BSID-II)2

Mexican Study
  • DDE exposure in utero
  • Study found a decrease in psychomotor development
    using BSID-II at 3, 6 and 12 months2

Common theme
  • The common result from the CHAMACOS, Spanish, and
    Mexican studies suggests that DDE may have a
    negative effect on psychomotor development in
    infants less that 12 months of age
  • Only the North Carolina cohort had a positive
    association with decreased mental development at
    6 months of age2

How Bad can Pesticide Exposure Be?
  • First, we need to determine what the
    environment in relation to pregnancy
  • One known example of a hazardous environmental
    toxin is tobacco smoke
  • The neonatal environment can include nutrition,
    adequacy of prenatal care, smoking, alcohol use,
    maternal age and socioeconomic conditions
  • Two or more of these factors might be related or

Physical Environmental
  • A mothers physical environmental is what most of
    us are familiar with
  • Air, water, food, soil and a number of consumer
  • A mothers placenta is thought of to protect a
    fetus against any toxins encountered, however
    some cases have shown the placenta to actually
    magnify hazardous maternal exposures3

Santa Ana Wildlife Reserve
Physical Environmental
  • For some persistent and bioaccumulative exposures
    (i.e. organochlorine pesticides), fetal exposure
    can occur as a result of maternal body burdens
    from years of preconceptional exposures
  • Fathers are just as accountable for exposures
    since their preconceptional exposures contribute
    to the risk through a mutagenic mechanism
    involving the sperm3

Neurodevelopmental Effects
  • Not specifically targeting pesticide exposure,
    environmental contaminants have been known to
    have adverse effects on brain and neurological
  • Some developmental disabilities include ADHD,
    learning disabilities, autism, mental retardation
    and effects on the nervous system
  • Studies have shown that the window of
    susceptibility is with prenatal exposures
  • Toxicological studies link both prenatal and
    postnatal exposure to organophosphate pesticides
    to neurodevelopmental effects3

  • This research focused on prenatal exposure and
    not on adolescent or adult effects

Future Research
  • Due to limited human population studies of
    pesticide exposure, more research is needed
    particularly with preconception exposures. This
    research should include both maternal and
    paternal exposures.

  • One recommendation for the detection of
    pre-exposure to the fetus
  • Include a questionnaire during prenatal care
    about possible environmental exposures for the
    expectant parents
  • This environmental assessment should be
    particularly conducted in agricultural
    communities where pesticide exposure is more

You too can be a basketball star without
excessive exposure to pesticides.
  • Rosas, L.G. and Eskenazi, B. (2008). Pesticides
    and Child Neurodevelopment. Current Opinion in
    Pediatrics, Vol. 20, 191-197.
  • Eskenazi, B., Rosas, L.G., Marks, A.R., Bradman,
    A., Harley, K., Holland, N., Johnson, C.,
    Fenster, L., Barr, D.B. (2008). Pesticide
    Toxicity and the Developing Brain. Basic
    Clinical Pharmacology Toxicology, Vol. 102,
  • Stillerman, K.P., Mattison, D.R., Giudice, L.C.,
    Woodruff, T.J. (2008). Environmental
    Exposures and Adverse Pregnancy Outcomes A
    Review of the Science. Reproductive Sciences,
    Vol. 15 (7), 631-650.
  • US Environmental Protection Agency. About
    pesticides. 2006. Available at
    Accessed July 25, 2009.
  • American Pregnancy. Pesticides Exposure During
    Pregnancy. 2009. Available at
    esticides.html. Accessed July 25, 2009.

This presentation was created in memory of Dr.
Kirby K.C. Donnelly