Endocrine DisruptionFaith M. OiUniversity of FloridaEntomology and Nematology Dept.Gainesville, FL email@example.com
The ConcernsEndocrine disrupting chemicals (EDCs) have been implicated in everything from alligator feminization to human infertility, cancer and recently obesity.EPA is beginning Tier 1 screeningTier 2 concentrates on dosesDocumentation has been and will continue to be difficult and controversial
EDC Brief History1930s, observations that synthetic chemicals could mimic hormones1991, WingspreadChemically induced alternations in sexual development: The wildlife/human connection
EDC Brief HistoryMany 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.
The Endocrine Disruption Screening Program
Investigations into the Effects of EDCsSperm qualityseveral studies report declineFertilityimplication, exposure to high levels can impair fertility and increase rate of miscarriageAbnormalities in male sex organsPrecocious pubertyAssociation with certain cancersTesticular cancer increase from 1973 to 1999 across all age groupsCaucasian: 51.8%African-American: 49.4%Breast cancer increase Caucasian: 27.9% African-American: 34.8%Brain cancer increase in children 14 or younger50.2%
Routes of ExposureOral-- ingestion
Dermal-- skin contamination (60-90%)
Inhalation-- breath airborne insecticides (
Acute ToxicityDefinition: Ability of a chemical to do systemic damage resulting from a single exposure to a relatively large doseEffects are usually seen within minutes to hours of exposure
How Does the LD50 Work?The ConceptAcute toxicity is measured by the LD50LD50 (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.
http://web.bryant.edu/~dlm1/sc372/readings/toxicology/endocrinedisrupter.jpgSome 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 hormonesEpa.gov
Endocrine DisruptionThe Readers Digest VersionEndocrine system secretes hormones into the blood stream and works in conjunction with the nervous systemEDCs 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
Endocrine DisruptionThe Readers Digest VersionHypothalamus - 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.
Endocrine DisruptionThe Readers Digest VersionPancreas - 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.
Endocrine DisruptionThe Readers Digest VersionChildren are not little adultsPound for pound, a childs exposure is greater than an adults (dose-response)Immature blood-brain barrierallows more chemical passageDetoxication systems may not be fully functionaltiming of exposure.
Endocrine DisruptionThe Readers Digest VersionBecause 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.