Endocrine Disruptors _ AP Environmental Science Class Notes _ Fiveable

Overview of Endocrine Disruptors

  • Certain chemicals, both natural and manmade, negatively affect ecosystems.

What are Endocrine Disruptors?

  • Chemicals that alter hormone functions in the endocrine system.

  • The endocrine system consists of glands that release hormones, including ovaries, testes, adrenal glands, and pituitary gland.

The Endocrine System

  • Components: Ovaries, testes, parathyroid glands, adrenal glands, pituitary gland, pineal body, pancreas, and hormone-releasing cells.

  • Function: Regulates various biological processes through hormones.

Examples of Hormones

  • Adrenocorticotropic hormone (ACTH): Controls the release of corticosteroid hormones from adrenal glands.

  • Thyroid hormones: Regulate growth, development, and metabolism for cells.

  • Antidiuretic hormone (ADH): Stimulates water reabsorption in kidneys.

  • Insulin: Regulates blood sugar levels.

  • Epinephrine and Norepinephrine: Stress response hormones.

  • Testosterone: Primary male sex hormone.

  • Estrogen: Primary female sex hormone.

Where are Endocrine Disruptors Found?

  • Found in everyday items like plastic products, foods, and pesticides.

  • Common disruptors include BPA, triclosan, and perchlorate.

    • BPA Free: Products labeled as such are free from this disruptor.

Effects of Endocrine Disruptors on Ecosystems

  • Cause anomalies in growth and reproduction in wildlife.

  • Increased risk of birth defects and reproductive issues in both aquatic and terrestrial organisms.

  • Long-lasting exposure among organisms due to slow breakdown of certain chemicals.

  • Difficulty in determining specific disruptors responsible for observed effects.

Effects on Wildlife

  • Documented effects include:

    • Egg thinning in birds.

    • Imposex in mollusks (female genitalia resembling male).

    • Feminization of freshwater fish from sewage exposure.

    • Reproductive abnormalities in alligators and turtles.

  • Possible effects with less evidence include reproductive issues in whales and seals, immune dysfunction in seals, and skeletal abnormalities in frogs.

Effects on Humans

  • Minor hormonal changes can lead to significant developmental and biological outcomes.

  • Reported changes in human health:

    • Increase in male genetic deformities.

    • Rise in hormonally linked cancers.

    • Decline in sperm counts in some regions.

  • Further research is needed to explore:

    • Mechanisms of endocrine disruptors.

    • Effects of low-dose exposure.

    • Mixed exposure to multiple disruptors.

    • Vulnerability across different ages.

Examples of Endocrine Disruptors

  • Bisphenol A (BPA): Used in plastics, found in food storage containers.

  • Triclosan: Present in antimicrobial products.

  • Dioxins: Byproducts of industrial processes, persistent in the environment.

  • Polychlorinated biphenyls (PCBs): Used in electrical equipment, toxic and banned due to health risks.

  • Perchlorate: Contaminates water, affects thyroid function.

  • Polybrominated diphenyl ethers (PBDEs): Flame retardants linked to health issues.

  • Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS): Used in firefighting foams and nonstick products.

  • Phytoestrogens: Plant-derived compounds mimicking hormones, present in some soy products.

  • Phthalates: Used in plastics, cosmetics, and food packaging.