environmental toxicology

Question 1

what are HAP?

HAP = hazardous air pollutants

Answer 1

from human-made sources, vehicles, stationary (factoriws, power plants), indoor sources (building structure, cleaning solvents)

Question 2

how are we exposed to HAP

Answer 2

• breath contaminated air
• eating contaminated food products
• ingesting contaminated soil
• touching contaminated soil, dust or water

Question 3

toxicity of ozone?

the stratosphere part

Answer 3

• in stratosphere, ozone will be formed thanks to UV light
• UV light will breakdown O2 to 2 oxygen atoms
• the cycle
  
  • 1 atom of oxygen bind to molecule of O2 –> create O3 (ozone)
  • build up of O3 form ozone layer –> plays important role, protects us from short wavelength of UV, by absorbing it
  • ozone is threatened by Cl2 and CFC –> cause holed in ozone layer

Question 4

toxicity of ozone? (pt.2)

in the trophosphere part

Answer 4

• near earth’s surface there is nitrogen dioxide (from cars)
• in the afternoon (sun very bright), NO2 will react with sunlight and UV light
• UV light will cleave NO2 -> divide into NO and O
• O will react with surrounding O2 –> form O3
• NO will react with O3 –> NO2 and O
• cycle will repeat again
• build up of O3 –> deformation of more NO2 molecules –> not good for our respiratory tract and the ozone layer as well
  
  • cause pulmonary fibrosis

Question 5

mechanism toxicity of O3? (in our body)

Answer 5

• inhaled ozone will release inflammatory mediators (TNF)
• release of this will activate fibroblast to migrate inside the alveoli and proliferate
• will form wound clot –> lead to formation of blood vessels (angiogenesis) –> once angiogenesis is severe, will lead to fibrosis
• other inflammatory mediators will interfere
• will form cystuc spaces between the alveoli (mass of fibroblasts)

Question 6

mechanism toxicity of NO2?

is different from the ozone one

Answer 6

• NO2 can cause oxidative stress in the lung –> slowly lead to necrosis –> inflammation of the pulmonary edema –> cause fibrotic changes within the lungs
• strong oxidator (ex: Fe2+ into Fe3+) –> cause methehemoglobinemia (blue skin, cyanosis)

Question 7

mechanism toxicity of CO?

Answer 7

mostly produce by emission from vehicles (emission depends on traffic density)
* CO binds with hemoglobin –> form carboxyhemoglobin (COHb)
* COHb is normally present <2% –> continuous exposure to CO –> increase exposure
* COHb reduce the concentration of O2 delivered to vital organs –> cause hypoxia and cyanosis

Question 8

how dangerous is CO?

Answer 8

because CO is:
* colorless, tasteless, and odorless gas –> cannot be sure of exposure
* cause nausea, vomiting, fatigue, loss consiousness, fatally can cause death
* can also come from stoves, coal being lit in unventilated room