Q 3: Endocrine Disrupting Chemicals Flashcards
Systems to communicate hormones: 3
With evolution of multicellular organisms,
cells took on different functions
• Communication between cells was essential
for maintaining physiological homeostasis
-Nervous System
-Endocrine System
-Immune
hormones?
HORMONES provide chemical communication
and physiological regulation / coordination
Endocrine System
Chemical Signal–>Blood–>Target Cells
Endocrine Disruptors?
hormone mimic=
any exogenous agent that causes
adverse health effects in an organism or its
offspring due to changes in endocrine function
Humans have “invented” almost _______ new
chemicals in the past century for various purposes
Humans have “invented” almost 100,000 new
chemicals in the past century for various purposes
-The majority of these chemicals have not been
adequately tested for their ability to interfere with
the endocrine system
Persistent Environmental Polutants: 3
Organochlorine pesticides (e.g. DDT) Polychlorinated biphenyls (PCBs) “Dioxins”
Industrial Chemicals(3)
Phthalates- Plastics Soft ex: IV bags
Bisphenol A- Hard Plastics(polycarbonate)
Detergents (e.g. alkylphenols)
Pharmaceuticals(2)
Diethylstilbestrol (DES)- Birth Control
Ethinyl estradiol- Like Thalidomide, birth defects
Designed to be very potent and longer lasting then other kinds of disruptors
Heavy Metals(3)
Lead
Cadmium
Mercury
Natural Plant Products
Genestein
Flavones
Complex Environmental mixtures
Pulp and paper mill effluents
Petroleum refinery effluents
Plastics industry
6 classes of endocrine disruptors
- Persistent Environmental Polutants
- Industrial Chemicals
- Pharmaceuticals
- Heavy Metals
- Natural Plant Products
- Complex Environmental mixtures
Legacy Chemicals
persistent original chemicals
4 Problems with many of these chemicals
- Environmental persistence / stability
- resistant to degradation and metabolism - Lipophilicity - fat solubility causes accumulation
- Bioaccumulation - repeated exposure (e.g. food)
- Biomagnification - increased concentrations at
each higher level of food chain
Lipophilicity
Fat solubility causes accumulation
Bioaccumulation
repeated exposure(ex: food)
Biomagnification
increased concentrations at each higher level of food chain
Fish, Amphibians, Reptiles, Invertebrates- effects of endocrine disrupting
Fish - exposed to various pollutants - reproductive impairment - “intersex”-female aspects included Reptiles - Florida alligators Amphibians - dont really know affects Invertebrates - many examples of sex reversal
Key points of endocrine disruption: 2
Early life stages (i.e. embryo, neonate) are the most sensitive due to complex developmental processes occurring • Endocrine system provides most of the regulation of these processes
Evidence in humans
. Increasing incidence of cancers in
endocrine-responsive reproductive tissues
. Decreased Sperm Count
.Development affects on fetus and children
. “deficits”- IQ, behavior
e.g. breast, endometrial, ovarian, prostate, testicular • biased by increased detection e.g. mammography, prostate-specific antigen (PSA test)
Human Health Risk Assessment
Human health risk assessment is focused
mainly on cancer and terata (birth defects)
It is NOT based on subtle functional
deficits such as sublethal effects on
reproduction, behaviour, immune system,
central nervous system
Why are Subtle functional deficits ignored in Human health risk assessments?
• Difficult to identify and measure subtle effects in humans • Long term, delayed effects • Potentially trans-generational (passed on to offspring)
