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Environmental Toxicology
Environmental toxicology is the study of the effects of pollutants on organisms, populations, ecosystems, and
biosphere
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Hazardous air pollutants (HAP)
a
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b
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g
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g
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g
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Examples: benzene,
methylene chloride, dioxin,
asbestos, toluene, and
metals such as cadmium,
mercury, chromium, and lead compounds
d
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II
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Known as photochemical air pollution
b
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it is a pale blue gas with a
distinctively pungent smell
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O3 initiate propagation of lipid radicals and auto
oxidation of cell membranes
d
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O2 + UV → 2O•
ii
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Overall reaction: 3O2 + UV → 2O3
Nitrogen dioxide and UV
i
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O• + O2 → O3

Barrier for short-wavelength
UV
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O3 + NO• → NO2
f
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Centriacinar interstitial fibrosis
i
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Studies of 18-month chronic exposure to O3 at 0
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Toxicity of Nitrogen Dioxide (NO2)
a
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Exposure with unventilated gas stoves or
burning of biomass fuels
c
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WHO limit: <20 ppb per day annually or
<100 ppb per hour (acute)
e
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NO2 is a strong oxidator → oxidize Fe2+ into
Fe3+ → cause methemoglobinemia

g
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edema → fibrotic changes within the lung
Toxicity of Carbon Monoxide (CO)
a
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b
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CO can bind with hemoglobin → carboxyhemoglobin
(COHb) (200 times more affinity than O2)
d
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COHb reduce concentration of O2 delivered to vital
organs
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Hazardous air pollutants are pollutants that are known to cause cancer and other serious health
impacts
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O3 can cause toxicity through causing fibrosis in bronchioles and alveolar ducts in lung
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NO2 can cause toxicity by causing pulmonary edema
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4
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This causes the
concentration of O2 delivered to organs be lesser

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