Q 3: Endocrine Disrupting Chemicals

Question 1

Systems to communicate hormones: 3

Answer 1

With evolution of multicellular organisms,
cells took on different functions
• Communication between cells was essential
for maintaining physiological homeostasis
-Nervous System
-Endocrine System
-Immune

Question 2

hormones?

Answer 2

HORMONES provide chemical communication

and physiological regulation / coordination

Question 3

Endocrine System

Answer 3

Chemical Signal–>Blood–>Target Cells

Question 4

Endocrine Disruptors?

Answer 4

hormone mimic=
any exogenous agent that causes
adverse health effects in an organism or its
offspring due to changes in endocrine function

Question 5

Humans have “invented” almost _______ new

chemicals in the past century for various purposes

Answer 5

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

Question 6

Persistent Environmental Polutants: 3

Answer 6

Organochlorine pesticides (e.g. DDT)
Polychlorinated biphenyls (PCBs)
“Dioxins”

Question 7

Industrial Chemicals(3)

Answer 7

Phthalates- Plastics Soft ex: IV bags
Bisphenol A- Hard Plastics(polycarbonate)
Detergents (e.g. alkylphenols)

Question 8

Pharmaceuticals(2)

Answer 8

Diethylstilbestrol (DES)- Birth Control
Ethinyl estradiol- Like Thalidomide, birth defects

Designed to be very potent and longer lasting then other kinds of disruptors

Question 9

Heavy Metals(3)

Answer 9

Lead
Cadmium
Mercury

Question 10

Natural Plant Products

Answer 10

Genestein

Flavones

Question 11

Complex Environmental mixtures

Answer 11

Pulp and paper mill effluents
Petroleum refinery effluents
Plastics industry

Question 12

6 classes of endocrine disruptors

Answer 12

1. Persistent Environmental Polutants
2. Industrial Chemicals
3. Pharmaceuticals
4. Heavy Metals
5. Natural Plant Products
6. Complex Environmental mixtures

Question 13

Legacy Chemicals

Answer 13

persistent original chemicals

Question 14

4 Problems with many of these chemicals

Answer 14

1. Environmental persistence / stability
   - resistant to degradation and metabolism
2. Lipophilicity - fat solubility causes accumulation
3. Bioaccumulation - repeated exposure (e.g. food)
4. Biomagnification - increased concentrations at
   each higher level of food chain

Question 15

Lipophilicity

Answer 15

Fat solubility causes accumulation

Question 16

Bioaccumulation

Answer 16

repeated exposure(ex: food)

Question 17

Biomagnification

Answer 17

increased concentrations at each higher level of food chain

Question 18

Fish, Amphibians, Reptiles, Invertebrates- effects of endocrine disrupting

Answer 18

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

Question 19

Key points of endocrine disruption: 2

Answer 19

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

Question 20

Evidence in humans

Answer 20

. 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)

Question 21

Human Health Risk Assessment

Answer 21

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

Question 22

Why are Subtle functional deficits ignored in Human health risk assessments?

Answer 22

• Difficult to identify and measure subtle
effects in humans
• Long term, delayed effects
• Potentially trans-generational
(passed on to offspring)