Endocrine Disruption

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Endocrine Disruption

• Faith M. Oi
• University of Florida
• Entomology and Nematology Dept.
• Gainesville, FL 32611
• foi_at_ufl.edu

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The Concerns

• Endocrine disrupting chemicals (EDCs) have been
  implicated in everything from alligator
  feminization to human infertility, cancer and
  recently obesity.
• EPA is beginning Tier 1 screening
• Tier 2 concentrates on doses
• Documentation has been and will continue to be
  difficult and controversial

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EDC Brief History

• 1930s, observations that synthetic chemicals
  could mimic hormones
• 1991, Wingspread
• Chemically induced alternations in sexual
  development The wildlife/human connection

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EDC Brief History

• Many compounds introduced into the environment
  by human activity are capable of disrupting the
  endocrine system of animals, including fish,
  wildlife, and humans. Endocrine disruption can
  be profound because of the crucial role hormones
  play in controlling development.

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The Endocrine Disruption Screening Program
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Investigations into the Effects of EDCs

• Sperm qualityseveral studies report decline
• Fertilityimplication, exposure to high levels
  can impair fertility and increase rate of
  miscarriage
• Abnormalities in male sex organs
• Precocious puberty
• Association with certain cancers
• Testicular cancer increase from 1973 to 1999
  across all age groups
• Caucasian 51.8
• African-American 49.4
• Breast cancer increase
• Caucasian 27.9
• African-American 34.8
• Brain cancer increase in children 14 or younger
• 50.2

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Routes of Exposure

• Oral-- ingestion
• Dermal-- skin contamination (60-90)
• Inhalation-- breath airborne insecticides (lt1)
• Ocular-- eyes

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Acute Toxicity

• Definition Ability of a chemical to do systemic
  damage resulting from a single exposure to a
  relatively large dose
• Effects are usually seen within minutes to hours
  of exposure

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How Does the LD50 Work?The Concept

• Acute toxicity is measured by the LD50
• LD50 (Lethal Dose) Dose that it takes to kill
  50 of the test population

Who invented the concept of the LD50? J. W.
Trevan, 1927. Was trying to estimate relative
poisoning effects of drugs and medicines.
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• Some chemicals mimic a natural hormone, fooling
  the body into over-responding to the stimulus
  (e.g., a growth hormone that results in increased
  muscle mass), or responding at inappropriate
  times (e.g., producing insulin when it is not
  needed).
• block the effects of a hormone from certain
  receptors (e.g. growth hormones required for
  normal development).
• directly stimulate or inhibit the endocrine
  system and cause overproduction or
  underproduction of hormones
• Epa.gov

http//web.bryant.edu/dlm1/sc372/readings/toxicol
ogy/endocrinedisrupter.jpg
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http//www.scientificamerican.com/media/inline/new
-website-maps-endocrine-disruptors_1.jpg
http//www.niehs.nih.gov/health/topics/agents/endo
crine/images/plastics.jpg
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Endocrine DisruptionThe Readers Digest Version

• Endocrine system secretes hormones into the blood
  stream and works in conjunction with the nervous
  system
• EDCs mimic hormones and interfere with synthesis,
  secretion, transport, binding, action or
  elimination of natural hormones.
• EDCs are bad for adults, worse for children and
  worst for unborn children of parents who are
  exposed

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Endocrine DisruptionThe Readers Digest Version

• Hypothalamus - The hypothalamus links our
  endocrine and nervous systems together. The
  hypothalamus drives the endocrine system.
• Pituitary gland - The pituitary gland receives
  signals from the hypothalamus. The posterior lobe
  secretes hormones that are made by the
  hypothalamus. The anterior lobe produces its own
  hormones, several of which act on other endocrine
  glands.

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Endocrine DisruptionThe Readers Digest Version

• Pancreas - The pancreas is responsible for
  producing glucagon and insulin. Both hormones
  help regulate the concentration of glucose
  (sugar) in the blood.
• Gonads - produce steroids that affect growth and
  development and also regulate reproductive cycles
  and behaviors. The major categories of gonadal
  steroids are androgens, estrogens, and
  progestins, all of which are found in both males
  and females but at different levels.

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Endocrine DisruptionThe Readers Digest Version

• Children are not little adults
• Pound for pound, a childs exposure is greater
  than an adults (dose-response)
• Immature blood-brain barrierallows more chemical
  passage
• Detoxication systems may not be fully
  functionaltiming of exposure.

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Endocrine DisruptionThe Readers Digest Version

• Because children have more future years of life
  than most adults, they have more time to develop
  chronic diseases that may be triggered by early
  exposures.
• Landrigan et al. 2003. Assessing the effects of
  endocrine disruptors in the national childrens
  study. Environ. Health Perspectives 111(13)
  1678-1682.

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Solution?
Err on the side of caution
IPM! Or Green???