Chemical Hazards and GHS Quick Notes

Chemical hazards and hazardous chemicals

Definition: An occupational hazard involving potentially harmful chemicals; includes flammable, reactive, and corrosive substances.
Examples: Cleaning products, pesticides, gasoline.

Characteristics of hazardous chemicals

Persistent: stays in the environment for long periods and does not biodegrade easily. $\text{persistence}$
Bioaccumulative: builds up in organisms and moves through the food chain. $\text{bioaccumulation}$
Toxic to organisms: can cause cancer, nervous system damage, reproductive harm, hormonal disruption, etc. $\text{toxicity}$
Endocrine disrupting chemicals (EDCs): disrupt proper hormone function; the endocrine system is crucial for health. $\text{EDC}$

Endocrine disrupting chemicals (EDCs)

Disrupt hormones; hormones are chemical messengers in the endocrine system.

Global Harmonized System (GHS)

Developed by the United Nations for international standardization of hazard classification and communication.
Key components: hazard classification, labeling, and Safety Data Sheets (SDS).
Agencies: OSHA (Occupational Safety and Health Administration); SDS = Safety Data Sheet.

GHS label elements

Hazard statements: e.g., ":DANGER" for severe hazards; ":WARNING" for less severe hazards.
Example statement: "+Fatal if inhaled or swallowed+" for highly toxic chemicals.
Labels communicate hazard level quickly to users.

Legal requirements under GHS

Manufacturers/distributors must evaluate chemical hazards of their products.
They must provide Safety Data Sheets (SDS) describing classification and known hazards.

GHS hazard classifications (high-level)

Health hazards: toxicity, carcinogenicity, mutagenicity, reproductive toxicity, respiratory sensitization, target organ toxicity, etc.
Physical hazards: corrosion/irritation, explosives, flammable substances, oxidizers, self-reactives, organic peroxides, gases under pressure, etc.
Environmental hazards: aquatic toxicity and related environmental risks.
Special/non-mandatory hazards: ozone depletion, etc.

GHS hazard statements and pictograms (examples)

Pictograms include:
- CORROSION: skin corrosion/burns, eye damage, corrosive to metals
- EXCLAMATION MARK: irritant, skin sensitizer, acute toxicity, narcotic effects, respiratory irritant
- EXPLODING BOMB: explosives, self-reactives, organic peroxides
- FLAME: flammable liquids/solids, self-heating, emits flammable gas on contact with water, self-reactives, organic peroxides
- GAS CYLINDER: gases under pressure
- ENVIRONMENT: aquatic toxicity
- HEALTH HAZARD (star figure): carcinogen, mutagenicity, reproductive toxicity, respiratory sensitizer, target organ toxicity, aspiration toxicity
- FLAME OVER CIRCLE: oxidizers, some toxic effects

GHS hazard classes (summary)

Health: acute toxicity, skin corrosion/irritation, eye damage, carcinogenicity, mutagenicity, reproductive toxicity, etc.
Physical: explosives/self-reactives/organic peroxides, flammable gases/liquids/solids, pyrophorics, self-heating, gas under pressure, oxidizers, corrosive to metals
Environmental: aquatic toxicity

GHS classification details (high-level)

Health toxicity: 5 categories (two reclassified) including severe to moderate toxicity; categories span from severe to milder effects.
Corrosivity: includes severe skin and eye damage; corrosion to metals; further subcategories for severity.
Mutagenicity, Carcinogenicity, Reproductive toxicity: long-term health effects; multiple categories.
Target organ toxicity, Respiratory sensitizers, Aspiration toxicity: additional health endpoints.
Environmental: four categories for aquatic toxicity.
Physical hazards: explosives, flammable materials, self-reactives, organic peroxides, oxidizers, gases under pressure, etc.

Major groups of hazardous chemicals in Australia

Major groups: Dangerous Goods, Scheduled Drugs/Poison, Hazardous Substances and Chemicals.
The Australian Dangerous Goods Code (ADG) governs classification for transport safety.

Dangerous Goods (ADG) classifications in Australia

9 classes:
- Class 1 – Explosives
- Class 2 – Gases (compressible, liquefied, dissolved under pressure)
- Class 3 – Flammable liquids
- Class 4 – Flammable solids, substances liable to spontaneous combustion, substances which emit flammable gases on contact with water
- Class 5 – Oxidizing substances and organic peroxides
- Class 6 – Toxic and infectious substances
- Class 7 – Radioactive substances
- Class 8 – Corrosive substances
- Class 9 – Miscellaneous dangerous goods

Class 1: Explosives (Divisions)

Division 1.1 mass explosion hazard
Division 1.2 projection hazard
Division 1.3 fire hazard with minor blast or projection hazard
Division 1.4 no significant hazard beyond the package
Division 1.5 very insensitive mass explosion hazard
Division 1.6 extremely insensitive with no mass explosion hazard

Class 2: Gases

Division 2.1 Flammable gases
Division 2.2 Non-flammable, non-toxic gases
Division 2.3 Toxic gases
Division 2.4 Subdivision risk associated with oxidizing gases

Class 3: Flammable liquids

Liquids capable of ignition and sustained burning; higher vapor pressure increases hazard; liquids can flow and accumulate in low points
Packed into Packing Groups (PG) I–III by hazard level and flash point/boiling point

Class 4: Flammable solids

Division 4.1 Flammable solids, self-reactive substances, desensitized explosives
Division 4.2 Substances liable to spontaneous combustion
Division 4.3 Substances that emit flammable gases in contact with water

Class 5: Oxidizing substances and organic peroxides

Division 5.1 Oxidizing substances (oxygen release that can enhance combustion)
Division 5.2 Organic peroxides (potential for explosive decomposition, rapid burn, reactivity)

Class 6: Toxic and infectious substances

Division 6.1 Toxic substances (poisoning potential by ingestion/inhalation/skin contact)
Division 6.2 Infectious substances (pathogens causing disease)

Class 7: Radioactive substances

Categories I–III based on surface radiation levels (Sv/hr)
Category I: ≤ 5 Sv/hr, Category II: > 5 to ≤ 500 Sv/hr, Category III: > 500 to ≤ 2000 Sv/hr

Class 8: Corrosive substances

Severe damage to living tissue; can damage/destroy materials; categorized I–III by danger level

Class 9: Miscellaneous dangerous goods

Substances and articles presenting danger not covered in other classes

The NFPA Diamond (Fire, Health, Reactivity, Special)

Four-color diamond: Health (blue), Fire (red), Reactivity (yellow), Special (white)
Scores range 0–4 for each of the three main areas; higher numbers indicate greater hazard
Special hazards include categories such as Acid, Alkali, Corrosive, Oxidizer, Radioactive, Use No Water

First aid for chemical incidents (essential steps)

Chemical first aid basics: Oxygen administration if necessary; avoid inducing vomiting unless instructed by professionals; seek medical help
Common scenarios:
- Skin splashes: flush with water; remove contaminated clothing
- Eye splashes: rinse with clean water/eye wash for at least 15 minutes
- Inhalation of vapor or gases: move to fresh air; monitor for respiratory symptoms
- Ingestion: do not induce vomiting unless told; seek medical advice
- Burns: apply appropriate burn care; seek medical attention

Oxygen administration (illustrative)

Oxygen delivery by mask with controlled flow and proper ventilation

Vomit induction and antidotes (caution)

Do not induce vomiting unless instructed by trained personnel; specific antidotes depend on chemical

Milk as an acid neutralizer (not universally advised; refer to SDS guidance)

Some guidance references using milk for minor acid neutralization; rely on official SDS and medical guidance

Quick recall tips

GHS focuses on hazard classification, labeling, and SDS
Recognize key pictograms: explosion, flame, flame over circle, gas cylinder, corrosion, health hazard, environmental hazard
Australia uses ADG with 9 Dangerous Goods classes and detailed subcategories
NFPA Diamond provides a snapshot of health, fire, reactivity, and special hazards
First aid priorities: prevent exposure, start with flushing/ventilation, seek medical help promptly