Simple asphyxiants Nitrogen Methane CO2 Chemical asphyxiants Carbon monoxide (Co) Hydrogen cyanide (HCN) Hydrogen sulphide (H2S) Systemically active gases Arsine (Powerful hemolytic agent) Stibene (Hemolytic agent) Phosphine (Respiratory irritant & neurotoxic) Irritant gases Upper respiratory irritants: Highly soluble in water → dissolved in URT → irritation ”Ammonia (NH3) & SO2” Lung tissue irritants: Less soluble in water → penetrate deep to lung tissue “Chlorine – Phosgene - Fluorine - NOx- O3

1. Dr. Dalia El-Shafei
Assoc.Prof., Community Medicine Department, Zagazig University
http://www.slideshare.net/daliaelshafei

2. Simple
asphyxiants
Nitrogen
Methane
CO2
Chemical
asphyxiants
Carbon monoxide
(Co)
Hydrogen cyanide
(HCN)
Hydrogen sulphide
(H2S)
Systemically
active gases
Arsine (Powerful
hemolytic agent)
Stibene (Hemolytic
agent)
Phosphine
(Respiratory irritant
& neurotoxic)
Irritant
gases
Upper respiratory
irritants: Highly
soluble in water →
dissolved in URT →
irritation
”Ammonia (NH3) &
SO2”
Lung tissue
irritants: Less
soluble in water →
penetrate deep to
lung tissue
“Chlorine –
Phosgene - Fluorine
- NOx- O3

8. Sources of incomplete combustion:
• Furnaces, boilers
• Internal combustion engine
(warehouses, auto plants)
Hazards increased in COLD weather
with closed doors & windows.

10. Firefighters Kiln &
furnace
operators
Garage
mechanics
Aircraft
refuelers
Truck Drivers Forklift
operators
Janitorial staff Disaster relief
workers
Miners Parking garage
attendants
Agricultural
workers

11. Chronic exposure to CO
NYC bridge & tunnel officers

13.  Binds to Hb more avidly than O2
(200x)
 Shifts oxygen dissociation curve
to “left”: Tissue anoxia
 Binds mitochondrial enzymes & myoglobin
(50x)
 Increases platelet stickiness
 Deceases arrhythmia threshold

14. % COHb = % CO in air X Time X K
At Rest
3
Light physical work
5
Heavy physical work
11

15. Ambient air
4-6 hs.
100% O2
40-60 min.
Hyperbaric O2
20-30 min.

17. Acute toxicity: depends on concentration of COHb in blood.
<10% No symptoms
At 10% Headache
10-20% Headache, tinnitus, dyspnea
20-30% As above + nausea, vomiting
30-45% As above + confusion, coma
> 50% Respiratory center depression & death

20. Chronic toxicity
Sleep
disturbance,
headache,
memory loss.
Arrhythmias
Myocarditis
Impaired
ANS

23.  Solvent: degreasing, paint stripping
 Absorption through respiratory route or through skin
 Metabolized in bloodstream to …… CO

24. May elevate COHb to 10% or more especially in poorly ventilated
space
Probably not significant to healthy person; may become mildly
symptomatic
Cigarette smokers, those with angina or current CHD a concern:
excess CO may trigger symptoms

25. Methylene Chloride
OSHA Standard: 25 ppm/ TWA8: STEL 125 ppm
NIOSH: As low as can be achieved (carcinogen)
Because of metabolic conversion to CO, the
biological life of COHb from methylene chloride
is longer than that from direct CO exposure

28. Carbon monoxide: Exposure limits

30. Prevention & control
Treatment
Continuous
environmental
assessment
PPE
Smoking cessation
program
Removal from
exposure
O2 “100% or
Hyperbaric”
Blood transfusion
Recommendation limits:
TLV: CO in respirable air is 50 ppm & COHb in blood is 5g/100g Hb.

34. Cyanide is a rapidly
acting, potentially
deadly chemical that
can exist in various
forms: a colorless gas
(hydrogen cyanide), a
colorless liquid, or in
form of crystals,
powder or pellets
(cyanide salts such as
sodium cyanide).
Cyanide is sometimes
described as having a
bitter almond smell,
but it does not always
give an odor, nor can
everybody detect it.
Cyanide is a naturally
occurring chemical
compound & is found
in several plants (e.g.
cassava roots,
almonds) and in
cigarette smoke.

38. Uses:
1- Fumigant (rodenticide, insecticide).
2- Extraction of silver & gold.
Mechanism of action:
- HCN absorbed through the lung.
- Excreted in urine & feces as thiocyanates.
- It inhibits cytochrome oxidase enzymes.

39. With a gold recovery rate of around 60-90%, its
performance is superior to mercury with a recovery
rate of 20-50%, depending on the processing
system. Sometimes, cyanide is used to capture
residual gold by leaching ore and tailings to which
mercury has previously been added – i.e. mercury
contaminated materials.

44. Toxicity
.
Headache, Confusion, Nausea,
Vomiting, Rapid weak
respiration, Convulsions, Coma &
Death.
Acute
Neurathenia
Psychic alterations
Allergic dermatosis
Chronic

47. Treatment
Removal from exposure
Amyle or Na nitrite
inhalation
Na thiosulfate IV infusion
Di cobalt EDTA (600 mg IV)
& Na thiosulfate

55. SEWER GAS
Sewer gasis a combination of non-toxic and toxic gases
that are present in sanitary and combined sewer collection
systems at varying levels depending on the source.
Elements of sewer gases include hydrogen sulfide,
methane, ammonia, carbon dioxide, sulfur dioxide and
nitrogen oxides, as well as biological organisms (bacteria,
viruses, etc.). Other components in sewer gas may include
substances that are improperly disposed of in sanitary
sewer systems, such as gasoline or solvents.

67. “King of Poisons, Poison of Kings”

69. Industrial processes
 Semiconductor manufacturing
(gallium arsenide)
 Fossil fuels
 Wood treated with arsenic
preservatives
 Metallurgy
 Smelting (copper, zinc, lead) &
refining of metals & ores
 Glass manufacturing
Commercial products
 Wood preservatives
 Pesticides
 Herbicides
 Fungicides
Food
 Seafood and fish
Others
 Antiparasitic drugs
 Folk remedies