Lecture 2 - Exposure Assessment Flashcards
Which chemicals are well-regulated?
- pesticides
-drugs
-drug additives
Most foods and food additives are not well regulated
What is Canada’s chemical management plan?
Canada has a domestic substances list for chemical management. This list includes chemicals most commonly produced in large volumes and most likely to be used in industry and on the market
The chemical management plan has 3 phases: 1,2,3
The # of substances dereases with each phase in order to focus action on a smaller # of chemicals
However, no new chemicals have been added sicne 2005 even though hundreds of new ones have been introduced since then
Exposure
Expsoure = how much x how long x how often
Expsoure = intensity x duration x frequency
Exposure=risk/hazard
The higher the exposure, the higher the (toxic) response and need fr worry
The expsoure rating can be expressed/classified as a % of the OEL (occupational expsoure limit)
Risk
Risk=exposure x hazard
Low expsoure and high hazard: low risk
The higher the expsoure, the higher the risk
The higher the hazard, the higher the risk
When both hazard and expsoure are high, the risk is high
Which data collection methods are best? (Best to worst)
- Quantitative personal dosimeter measurements
- Quantitative ambient measurements in vicinity of residence/work area of exposure
- Quantitative surrogates of expsoure (ex: estimates of drinking water)
- In proximity to area of exposure
- General geographic area pf spirce of expsoure
What can be sampled?
- air
- water
- soil
- food
- tissues (toxins mostly absorbed through the skin and through ingestion) –> subcutaneous and IV are less important in this
Where does air pollution come from?
- solid waste disposal Explosions Fires Pesticide drift Fuel combustion Industrial processes
How is air sampled and why must it be sampled?
Air pollution –> lung and CVS disorders; air particles get trapped at 0.5-5 um in size
How sampled? –> sampling devices contain a filter –> machine sucks in air and the filter between will test for chemicals
- however this does not work for volatile matter; thus we use absorbents
Sampling soil
-the assessment is dependent on the purpose of the land being examined –> there can be hanged in the types of toxicants dependign in the depths of the soil being tested
-normally 20-25 samples, depends on soil type, slope, fertilizer, text
Most veg gardens in city have higher levels of heavy metals than grocery veg
Sampling water
- need to look upstream and downstream of suspected/potential pollution site
- use grab technique
- need to continuously monitor water because it can be sampled at different intervals, which affects results
- in creasing levels of estrogen in water –> intersex fish –> less male fish
Polychlorinated Biphenyls (PCBs)
- Banned in North America
- Used as coolants in transformers to prevent overheating
- PCBs are still contaminating fish and shellfish i n the Great Lakes
- Pointe0Claire incident: leaked PCBs into surrounding land (1200L into nearby area)
Sampling Tissues
Tissue sampling occurs in:
- forensic studies
- experimental studies (metabolism, toxikientics, etc)
- environmental studies
Medical vs. Forensic Testing
Medical: -does not require consent -for patient care -must be sufficient evidence to make medical decision -results are used for medical evaluation -identity of specimen is required Forensic testing: -requires consent -huge in US companies -specimen must be proven to belong to the indiudal tested -identity of specimen is proven, only confirmed results are + -done for legal reasons
Forensic Toxicology
3 major types:
- postmortem
- workplace
- human performance
Postmortem toxicology
Began with Orfila who identified poisons in the 1800s
He provided proof that Marie LaFarge poisoned her husband with chronic arsenic
First person to identify cause of death by looking at chemicals
The field of forensic tox involves medical examiners and coroners, who investigate all weird deaths and test for chemicals in deceased people
Medical examiner: physician, 1877, no judicial powers, called to appear as witness
Coroners part of legal system, determine cause of death, much much older profession
