21 occupational health I Flashcards
what is this lecture about?
hazard recognition, exposure limits
-overview of hazard types
-case study
-TLV’s
what are the types of hazards?
-physical
-chemical or particulate
-biological
-ergonomic
-psychological
what are physical hazards?
sources of energy that lead to illness or injury
-noise
-radiation
-vibration
-temperature
-pressure (hyper/hypobaric)
-electricity
-contact with objects, machinery, surfaces, etc
what are chemical or particulate hazards?
-dusts and mists
-gases and vapors
-systemic poisons
-irritants
-corrosives
for example: welding fumes
what are biological hazards?
-bacteria
-fungi
-viruses
what are ergonomic hazards?
-biochemical: repetitive motion, static postures, forceful and prolonged exertion, etc
-workplace design
what are psychological hazards?
“stress”
-shift work
-abuse, harassment
what is a case study information?
-37 year old male
-3-4 week history of frequent headaches
-otherwise healthy
-headaches only work related: start within a few hours, better evenings and weekends
-notices other symptoms as well: dizzy, lack of coordination, lightheaded, fatigued, “sluggish”
-co-worker similar
what are the three points in assessing exposue?
-ask
-observe
-measure (quantify if possible)
what do we need to ask him?
whats his job?
-aircraft maintenance
-4 months ago, his company got a contract to repair/inspect military C-130 Hercules aircraft
-his job has been inspecting the fuel tanks in airplanes
-frequent exposure to jet fuel fumes
what was the cause of his headaches?
jet fuel: JP-4
-colorless to straw colored
-smells like gasoline/kerosene
made up of hydrocarbons
-kerosene
-alkanes
-cycloalkanes
-napthalenes
-benzene
how do we identify his exposure and hazard?
look at material safety data sheet
how can we quantify his exposure?
what are OELs?
occupational exposure limits
-are legal exposure limits (usually airborne) for workplace contaminants
-go by various names depending on jurisdiction (US, Canada, Europe, etc.-in Sask they’re called contamination limits or CLs)
-most jurisdictions base many of their OELs on the threshold limit values (TLVs) published by ACGIH (American conference of governmental industrial hygienists)
how are TLVs determined?
committees review existing published and peer reviewed literature in various disciplines:
-industrial hygiene
-toxicology
-occupational medicine
-epidemiology
-based on available literature, they conclude about appropriate levels of exposure
-this is an ongoing process, updates and changes occur every year
what is the definition of TLV?
“threshold limit values refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day over a working lifetime, without adverse health effects”
-TVLS are developed to protect workers who are normal, healthy adults
what is the legalese TLV definition?
“TVLs are guidelines to be used by professional industrial hygienists”
-are intended for use only as guidelines or recommendations to assist in hazard evaluation and control
-not for other use such as community air pollution, extended work periods, or proving/disproving disease in an individual
what is an important point in TLV definition in legalese?
“these values are not fine lines between safe and dangerous”
what are the types of TLVs?
- TLV-TWA (time weighted average)
- TLV-STEL (short term exposure limit)
- TLV-C (ceiling)
usually referred to as TWA, STEL and ceiling
what is TWA?
the average concentration for a conventional 8 hour workday and 40 hour work week, to which it is believed nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect
-often referred to as the 8hr-TWA
what is STEL?
a 15 minute average exposure that should not be exceeded at any time during a work day, even if the 8hr-TWA is within limits
the STEL is the concentration to which it is believed that workers can be exposed continuously for a short period of time with suffering from
-irritation
-chronic or irreversible tissue damage
-dose-rate-dependent toxic effects
-narcosis
what is ceiling?
the concentration that should not be exceeded during any part of working exposure
how do excursions work?
“excursions in worker exposure levels may exceed 3 times the TWA for no more than 30 minutes total during a workday, and under no circumstances should then exceed 5 times the TWA”
-this rule applies to those substances with a TWA that have no STEL
what are TLV examples from AGGIH handbook?
what are regulatory aspects?
-many jurisdictions have adopted the ACGIH TLVs as legal exposure limits
-enforced by occupational health and safety legislation
names vary (all mean the same thing)
-in Sask=contamination limits (CL)
-alberta=occupational exposure limits (OEL)
-US=permissible exposure limits (PEL)
how are saskatchewan contamination levels organized?
