EESA10H3 Lecture Notes - Lecture 9: Geographic Information System, Reproductive Toxicity, Absorbed Dose
2 Jul 2018
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EESA10 Lecture 9 – Toxicology
Fate & Transport – of chemicals = affected their physical-chemical properties
- Transport mvmts of contaminants w/in or b/w environmental media
- Fate physical, chemical/biological transformations of contaminants in the environment
- How harmful a substance = depends on physical-chemical properties of the substance
PHYSICAL-CHEMICAL PROPERTIES:
- Volatility
- Electronegativity
- Polarity
- Solubility
oWater soluble toxins
oFat soluble toxins (Lipophilic tendency)
CONSEQUENCES of Lipophilic Tendency:
Bioconcentration mvmt into fatty tissues of organisms
Bioaccumulation building up over time, in individual organisms
Biomagnification building up over time, across the lvls in a food chain
- Oxidation State
- Molecular weight
oMore lipophilic + more persistent
oLess volatile + less water-soluble
- Persistence in environment:
oQuantified as a half-life in air, water, or soil
oAffected by environmental conditions
find more resources at oneclass.com
find more resources at oneclass.com
TOXICOLOGY – science of effects of toxic substances + of their fate & transport in the body
“study of poisons”
“the science which studies toxic substances/poisons, that are substances which cause
alteration/perturbation in the function of an organisms leading to harmful effects” (Truhaut, 1974)
- Receptor
oOrganism (human?) receiving exposure or dose
oHuman Envelope – boundary that separates the interior of the body from the exterior
environment
oAge
oGeneral health
oGenetic makeup
- Exposure
oContact w/human envelope
oRoutes of exposure
Ingested (often greatest source of chemical exposure, 85%)
Inhaled (air pollution, particles + volatiles, 10%)
Absorbed through the skin (industrial, 5%)
oFrequency of exposure – goal to quantify exposure (or to find out DOSE)
Methods draw on understanding of both:
Environmental science (fate+transport of toxicants in environment)
Toxicology (fate+transport of toxicants in body)
Completing Conceptual Model of Exposure
find more resources at oneclass.com
find more resources at oneclass.com
Quantifying Exposure – translating event of exposure into a dose estimate
oPersonal monitoring a portable sampling device (incorporates
a pump that takes a continuous air sample near the subject’s
breathing zone; device also collects a sample of particulate
matter over the whole period)
Units of absorbed dose: mg/(kg*day)
oMass of toxicant
oNormalized to body weight
oAveraged over time
Other sources of exposure info
oQuestionnaires, diaries
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Fate & transport of chemicals = affected their physical-chemical properties. Transport mvmts of contaminants w/in or b/w environmental media. Fate physical, chemical/biological transformations of contaminants in the environment. How harmful a substance = depends on physical-chemical properties of the substance. Solubility: water soluble toxins, fat soluble toxins (lipophilic tendency) Bioconcentration mvmt into fatty tissues of organisms. Bioaccumulation building up over time, in individual organisms. Biomagnification building up over time, across the lvls in a food chain. Molecular weight: more lipophilic + more persistent, less volatile + less water-soluble. Persistence in environment: quantified as a half-life in air, water, or soil, affected by environmental conditions. Toxicology science of effects of toxic substances + of their fate & transport in the body. The science which studies toxic substances/poisons, that are substances which cause alteration/perturbation in the function of an organisms leading to harmful effects (truhaut, 1974)
