Lecture 19: Endocrine Disrupting Chemicals

Question 1

What are the common properties of endocrine disrupting chemicals

Answer 1

1. Ability to concentrate in tissues
2. Low degradation/high half lives even with low concentrations
3. Hydrophobic/lipophilic
4. High airborne potential- travel long distances

Question 2

What hormone does polybrominated diphenyl ether (PBDEs) resemble

Answer 2

Thyroid hormones

Question 3

How do PBDEs target the body

Answer 3

1. Bind to serum binding globulins
2. Deregulate thyroid hormone metabolic enzymes (synthesis)
3. Antagonistic or agonist effects

Question 4

Why are farm animals not sensitive to EDC’s

Answer 4

Varying trophic levels and eating low on food chain

Question 5

Why are farm animals good models for EDC’s

Answer 5

Similar in body size to, similar physiology to humans, similar gestation periods to humans
Outbred

Question 6

Study used silicon tags to track EDC’s and determined that cats with hyperthyroidism had a high likelihood of being exposed to flame retardant known as Bromkal 70-5DE.

What are some proposed mechanisms of exposure

Answer 6

1. Cats are consummate groomers
2. Many cats live indoors and spend lots of time on furniture
3. Older homes and resold furniture pose risk
4. PBDE’s in bromkal 70-5DE strongly resembles thyroid hormones