Asphyxiants (Toxicology Exam 3)

Front 1

What are asphyxiants?

Back 1

Things that you breathe that could damage you.

Front 2

What are the three kinds of asphyxiants?

Back 2

Chemical
Simple
Metabolic Poisons

Front 3

How do Simple Asphyxiants work?

Back 3

Displace O2 in air, creating Oxygen-deficient atmosphere

Front 4

Oxygen content of air (5) and related symptoms

Back 4

- 16-21% - normal, no symptoms
- 14-16% - incrs'd resp rate, HR, decrs'd coordination
- 10-14% - emotional instability, rapid exhaustion w/ exertion
- 6-10% - n/v, lethargy, LOC
- <6% - sz, cardiac arrest

Front 5

Examples of simple asphyxiants

Back 5

Nitrogen, methane, ethane, carbon dioxide

Front 6

Where might someone be exposed to simple asphyxiants?

Back 6

Work/play in poorly ventilated space with simple asphyx source:
- Mines
- Confined spaces - reactor vessels
- Dry ice in poorly ventilated areas (CO2 that sublimates)

Front 7

Prevention measure to stop simple asphyxiant injury

Back 7

VENTILATION
Confined spaces standard - OSHA
Keep air line respirators incompatible with anything other than air
Portable monitoring for O2-deficient atmosphere

Front 8

Chemical Asphyxiant - main example and MOA

Back 8

Carbon Monoxide
MOA: interfere with oxygen transfer and transport. Hgb has STRONG affinity for CO (220x that for O2), and once bound, it won't let it go. No O2 pickup at lung, no O2 delivery at tissues.

Front 9

Carbon Monoxide - Characteristics, Exposure sources

Back 9

Odorless, colorless
Cause of more poisoning deaths in US ages 6-12
Cause of more inhalation deaths than anything else
#1 inhalational/occupational cause of death in US
Sources:
- Indoor furnace, space heather, dryer, generators used indoors, tobacco smoke.
-Incrs'd deaths during flooding!
- Firefighting
-Methylene chloride - paint/enamel stripper, metabolized to CO in body

Front 10

Carbon Monoxide - Exposure Symptoms

Back 10

Flu-like symps - HA, nausea, fatigue
If high concentration exposure - decreased alertness
Can exacerbate underlying cardiac condition -chest pain
Severe: LOC, MI, death
After acute poisoning - problems with memory, coordination, mood

Front 11

Carbon Monoxide - susceptible populations

Back 11

Fetus (mom would be fine, baby would not)
People with underlying coronary disease

Front 12

Carbon Monoxide - how to measure in air and blood

Back 12

Air - ppm (10,000ppm = 1%)
Blood - %COHb

Front 13

Carbon Monoxide - treatment

Back 13

REMOVE FROM EXPOSURE, give O2
Unique: hypothermia, hyperbaric chamber

Front 14

Carbon Monoxide - Prevention and Regulation

Back 14

VENTILATION
Workspace regulation - 50ppm 8hr TWA (OSHA)
EPA - 9ppm for 8hr; 1 hr avg 35ppm
CO covered under NAAQS criteria
Downtown Chi usually <3ppm

Front 15

Metabolic Poison - MOA, Examples

Back 15

Interference with cellular respiration, aerobic metabolism, inhibits cytochrome oxidase & other enzymes.
Rapid knockdown
Ex: HCN (hydrogen cyanide), H2S (hydrogen sulfide)
Antidotes available for both

Front 16

Metabolic Poison: HCN

Back 16

Disrupts ability of cells to use O2 - they're getting it, but can't use it
Used in metal-plating, nylon manufxring, gold extraction from ore, generated when plastics burned
Bitter almond smell

Front 17

Metabolic Poison: H2S

Back 17

Disrupts ability of cells to use O2 - they're getting it, but can't use it
Generated in breakdown of organic material, more dense than air.
"Rotten egg" smell until olfactory paralysis

Front 18

Metabolic Poison: Methemoglobin

Back 18

Can be generated internally by oxidizing agents, which cause Fe2+ (ferrous) to become Fe3+ (ferric), which does NOT bind O2.
Creates hypoxic state, symptoms.
Treated with methylene blue

Front 19

Oxidants that cause methemoglobinemia

Back 19

Meds: nitroglycerin, sulfa drugs
Occ Exposures: aniline dyes, nitrates (NaNitrate, isobutyl nitrate), benzene, phenol, nitrophenol
Env Exposures: nitrate in well water, mnitrate/ammonium fertilizers (run-off gets into water supply)

Front 20

What causes "blue baby syndrome"?

Back 20

Well water high in nitrates used to make formula, infant has immature reducing enzymes, results in methemoglobinemia (hypoxic baby).