HAHs

Question 1

what usually dictates the toxicity of HAHs?

Answer 1

the more chlorinated the HAH, more persistence and toxic the molecule

Question 2

what is the most toxic HAH?

Answer 2

2,3,7,8-tetrachlorodibenzene-para-dioxin (2,3,7,8-TCDD or TCDD)

Question 3

half life of HAHs?

Answer 3

7-10 years

Question 4

what is the prototypes of HAHs?

Answer 4

TCDD

Question 5

what are the biological effects of HAHs?

Answer 5

1. wasting syndrome (anorexia)
2. thymic atrophy
3. chloracne
4. hepatotoxicity
5. IMMUNE SUPPRESSION
6. REPRO TOX
7. TERATOGENICITY
8. CARCINOGENICITY (non-genotoxic)
9. endocrine disruption
10. enzyme induction

Question 6

mech of tox of dioxins

Answer 6

• receptor specific to TCDD found in cytosol of hepatocytes;–known as aryl hydrocarbon receptor; orphan receptor; TCDD diffuses through cell into cytosol–binds to AhR–>dimerizes IN NUCLEUS and binds to DNA–transcribes CYP1a1, CYP1a2,nqo!,ALDh3a1, ugt1a6, and Gsta1 gene–make good biomarkers of AhR agonist exposure in wildlife
• also uncouples CYP–?produces ROS

Question 7

sources of PAHs

Answer 7

combustion of organic material– industrial (smelting);
domestic (municipal incinerators)
motor vehicle exhaust
forst fires–big contributor
tobacco
bbqs
major source in NA–burning wood in fireplaces

Question 8

biochemical effects of HAHs?

Answer 8

modulate hormones, receptors, growth factors, and receptors; enzyme induction