BIOL354 – Environmental Toxicology I Spring 2012
Lecture 3: Inorganic Pollutants
- Dose vs. Concentration
o Dose: Total amount of substance administered/taken/absorbed by organism.
Amount of solute if given in an aqueous form.
o Concentration: Quantity of substance per unit of a give medium/system (solute per solvent).
Actual amount inside the organism is UNKNOWN.
- Modification Factors: Factors that can change the toxicity of a toxicant.
o Biotic: Species, sex, age (Plastic: Bisphanol A w/ estrogen, great effect on developing boys), size, & nutrition.
o Abiotic: Exposure routes, partitioning (Organic Carbon as hydrophobic sediments), pH,2O (Oxidization),
hardness, temperature, & light.
- Inorganic Pollutants (Metals, metalloids, non-metallic inorganics & inorganic gases)
o Metals: (NATURALLY OCCURING @ low , majority are ANTHROPOGENIC)
Natural sources: Weathering of metal-bearing rocks.
Disposal/leaching from landfills.
Sewage sludge run-off when used as an inexpensive nutrient amendment.
Metal-based pesticides with arsenic & mercury (impacts CNS).
Ash & cinder disposal from burning firewood, incineration & cremation.
Lead pellets (Gizzards -> Lead poisoning); Pressure treated wood (Playground w/ arsenic,
chromium & copper); Tanning Leather, & “tawing” of pigs/goats (arsenic & chromium).
NOT BIODEGRADABLE, are lustrous, malleable, & good electrical conductors.
Can be an essential micronutrient or non-essential/toxic substance.
Metal speciation: form(s) of an element in a given sample.
o Free metal ions, inorganic metal complexes, simple organic metal complexes (EDTA)
& metal complexes w/ biotic organic matters (Fulvic/humic acids).
o Metals shift between species depending on factors like environmental pH, etc.
Bioavailability & toxicity can be affected by chemical speciation.
o Metal chelators: detoxifies by forming complexes with free metal ions.
Non-Essential metals: Cadmium: Batteries & paints; Chromium: Stainless steels; Lead: Extensively
in gasoline, paints & batteries, toxic; Mercury [NOT HIGHLY TOXIC]: dental amalgams, gold,
fungicides, thermometers, electrical tilt switches [Methylated mercury is EXTREMELY TOXIC].
Essential metals: Copper/Zinc/Iron, incorporated into macromolecules (large & organic) as chelates
or as enzyme co-factors (ATP, ADP, etc.) or they can exist as free ions.
Chelates: Hemoglobin (Fe ), hemocyanin (Cu ), & chlorophyll (Mg ).
o Limit+ reactivity/enhance+ affinity by trapping Oxyge2+molecules.
Free Ions: Na (osmoregulation), K (membrane potential) & Ca (various functions).
o High [KCl] injection: lethal & untraceable.
Non-metallic elements but with some similar properties to metals.
They are less lustrous & are semi-conductors (electronics).
Arsenic: in pesticides, wood preservatives, mine tailings, & playhouses, TOXIC.
o Non-metallic inorganics (Ammonia):
Ammonia (Un-ionized) NH [D3NGEROUS]
Ammonium cation (Ionized) NH 4
Tests usually checks BOTH [NH 3 NH ]4
Sources of release:
Point sources: [significant] municipal wastewater effluent discharges, high [30mg/L], can
kill a rainbow trout in less than 2 hours. BIOL354 – Environmental Toxicology I Spring 2012
Non-point sources: [trivial] landfills, fertilizers, household cleaners, pulp & paper, steel mills,
& [significant] farm manure.