8.3: Endocrine Disruptors & industrial Water Pollutants

Learning Objective:

  • Describe Endocrine Disruptors

  • Describe the effects of endocrine disruptors on ecosystems

Essential Knowledge:

  • Endocrine disruptors are chemicals that can interfere with the endocrine system of animals

  • Endocrine disruptors can lead to birth defects, developmental disorders, and gender imbalances in fish and other species

  • Heavy metals used for industry, especially mining and burning of fossil fuels can reach the groundwater, impacting the drinking water supply

  • When elemental sources of mercury enter aquatic environments, bacteria in the water convert it to highly toxic methylmercury.

Endocrine Disruptors:

Chemicals that interfere with the endocrine (hormonal) systems of animals

  • Bind to cellular receptors meant for hormones, blocking the hormone from being received, or amplifying its effects

  • Human medications that pass through urine & into sewage or are flushed down the toilet are a common source (meant to influence human hormones, so they can also disrupt animals)

    • EX: Atazine (herbicide) binds to receptors of cells that should convert estrogen into testosterone in male frogs, leading to: high estrogen in males, low sperm count, and even feminization (development of eggs in the testes or ovary formation)

Types of Disruptors:

  • Atrazine: Broad-spectrum herbicide used to control weeds & prevent crop loss

    • Applied to agriculture fields, runs off into local surface or groundwater or is carried by wind

    • Can contaminate human well water, or enter the body via unwashed produce

  • DDT: broad-spectrum Insectivide that was phased out, but still persists in the environment

    • Applied to agriculture fields, runs off into local surface or groundwater or is carried by wine

  • Phthalates: compounds used in plastic and cosmetic manufacturing

    • Enter surface & groundwater via intentional dumping of trash, or chemical waste from plastic/cosmetic factories improperly disposing of waste, landfill leaching

    • Also found in some cosmetics & plastic good containers (#3 plastic & “fragrance”)

  • Lead, Arsenic, Mercury: Heavy metals

  • Many human medications enter sewage via human urine or flushed meds.

Mercury:

  • Naturally occurring in coal, released by anthropogenic activities:

    • Coal combustion, trash incineration, burning medical waste, heating limestone for cement

      • Attaches to PM released by burning & deposits in soil/water wherever PM settles

      • Can be released if coal ash stored in ponds overflows & runoff

    • Endocrine disruptor: inhibits its estrogen & insulin (interferes with menstrual cycle & ovulation)

    • Teratogen: (chemical harmful to developing fetuses) can accumulate in the fetus's brain

      • Pregnant women can reduce risk by eating less seafood

    • Mercury itself isn’t toxic, but bacteria in water sources convert it to methylmercury which is highly toxic to animals (a neurotoxicant that damages central nervous systems)

Arsenic & lead:

  • Arsenic: naturally occurring element in rocks underground that can dissolve into drinking water; natural release into groundwater can be worsened by mining

    • Anthropogenic sources: formerly in pesticides applied to agriculture fields (can still linger in soil, wood treatment chemicals to prevent rot, coal combustion & ash

      • Carcinogenic (lungs, bladder, kidneys) & endocrine disrupting

      • Endocrine disruptor: (specifically glucocorticoid system)

        • Can be removed with water filters

  • Lead: Found in old paint (in homes), ld water pipes, and soils contaminated by PM from vehicles exhaust before lead was phased out of gas in 70s

    • Also release in fly ash (PM) of coal combustion

      • Neurotoxicant (damages CNS, especially in children)

      • Endocrine distuptor

        • Can be removed with water flters

Coal ash:

Coal Ash can be a source of mercury, lead, and arsenic

  • Can attach to fly ash (PM) from smokestacks and be carried by wind, deposited in ecosystems far away

  • Both fly and bottom coal ash are often stored on site in pounds, dug into soi & lined with plastic (sometimes)

    • Ponds can leach into groundwater, contaminating it with arsenic, lead, mercury

    • Ponds can overflow & run into nearby surface waters & agricultural fields