Make your own free website on

Hazardous Substances and Dangerous Goods

As part of our duties as an employee you may be required to handle or to come into contact with hazardous substances. A hazardous substance is something that is harmful to people, property and the environment.

Substances can be:


By law, any container holding a dangerous substance must be identified by the HAWHEM symbols and a Materials Safety Data Sheet should be available to personnel who are required to handle dangerous chemicals.

Here are some examples of dangerous chemicals that may be used in a food factory:

  • Caustic soda

a cleaning agent

  • Sodium hypochlorite (chlorine)
a sanitiser
  • Quanternary ammonium compounds (Quat)
a sanitiser
  • lodaphors (iodine)
a sanitiser

Material Safety Data Sheets

Food processing plants may have to use chemicals that are hazardous to store and to handle. Where hazardous chemicals have been identified in the workplace the company should ensure that they are labelled in accordance with the correct symbol.

The company should also keep the following documents:

  1. A record of all chemical products which note:

  2. A Materials Safety Data Sheet should be completed for each hazardous product. It should be readily available to all relevant operators and needs to include:

  3. A chemical register which is a combination of the two documents above should be maintained. All employees who are likely to use or come into contact with dangerous chemicals should be trained in:


Distinction between hazardous substances and dangerous goods

Hazardous substances

Hazardous substances are chemicals that are known to have immediate or short-term (acute) effects or long-term (chronic) effects on the health of workers.

Acute effects are immediately obvious for example, sneezing, coughing, itchy skin, watery eyes, headaches etc.

Chronic effects are more long term, sometimes as much as 10, 20 or 30 years after exposure to a hazardous substance. Some substances can have both acute and chronic effects.


Hazardous substances can enter the body by three distinct routes:


This is the major route of entry for hazardous substances into the body. For minor exposures where headache and dizziness occurs, it is important to leave the job and get some fresh air, moreover it is not recommended that the work continues until a proper risk assessment has taken place.


Through the skin. Skin contact with contaminated chemicals should be immediately treated by washing with soap and running water. Washing should continue for a few minutes to ensure that all the chemical residue has been removed from the skin.

Chemicals can be absorbed into the body when splashed into the eye. There is evidence that long term exposure to a high air concentration of some solvents may result in conjunctivitis and/or a clouding of the lens of the eye.


This is the least likely route of entry for substances into the body, personal hygiene is important.

Dangerous Goods

Dangerous goods are substances or articles considered potentially hazardous to people and property. Great care is required for the handling, storage and transportation of dangerous goods.

Dangerous goods are classified according to their common hazardous properties. Some dangerous goods are given one or more subsidiary risks, which means they have additional secondary hazards. For example: Chlorine gas is both poisonous (the primary risk) and oxidising (the secondary risk).

Class 1

Class 1: Explosives

Explosives are not compatible to be stored or transported with any other class of dangerous good. Explosives are substances or articles manufactured or used to produce a practical effect by explosion or a pyrotechnic effect.

Examples: Gunpowder, gelignite, fireworks, fuses, detonators.



Class 2

Class 2.1: Flammable gases

Gases which ignite on contact with a source of ignition. Most flammable gases are heavier than air, and as such, will flow to low areas, such as drains, pits and valleys.

Examples: Acetylene, Dissolved LPG - Liquified Petroleum Gases

Class 2.2: Non - flammable compressed gases

Gases that within themselves are not flammable when exposed to a source of ignition. Some of these gases are liquefied. Generally most non-flammable compressed gases are heavier than air. In some cases up to 6 or 7 times heavier than air. Some non-flammable gases can have a subsidiary risk category such as oxidising (5.1) or corrosive (8)

Examples: Air (refrigerated liquid), Oxygen (liquid)

compressed gas

These gases are liable to cause death or serious injury to health if inhaled. Most poison gases have a perceptible irritating odour. Some of these gases can also have a subsidiary risk such as flammable (2.1) oxidising (5.1) corrosive (8) or in some cases be both oxidising and corrosive e.g. nitrogen dioxide. Generally most gases are heavier than air.

Examples: Chlorine (gas), Methylene Bromide, Nitric Oxide.

Class 3

Class 3: Flammable liquids

Liquids which ignite on contact with a source of ignition. Liquids which have a flash point not higher than 61°C are not considered to be dangerous by virtue of their lower fire hazard. The vapours from all substances of Class 3 have the property of a more or less narcotic effect and prolonged inhalation may result in the person being unconscious or even dying.

Examples: Petrol, Kerosene, Paint Thinners.

flamable liquid

Class 4

Class 4.1: Flammable solids

The substances in this class are solids possessing the properties of being easily ignited by external sources, such as sparks and flames, and of being readily combustible, or of being liable to cause, or contribute to, fire through either friction or in some instances self reaction.

Examples: Sulphur, Phosphorus, Pictric Acid.

Class 4.2: Spontaneously combustible substances

The substances in this class possess the common property of being liable to heat spontaneously and to ignite. Some of these substances are more liable to spontaneous ignition when wetted by water, or in contact with moist air. Some may also give off toxic gases when they are involved in a fire.

Examples: Carbon, Charcoal, Non-Activated, Carbon Black.

Class 4.3: Dangerous when wet

The substances in this class are either solids or liquids possessing the common property, when in contact with water, of evolving flammable gases. In some cases these gases are liable to spontaneous ignition due to the heat liberated by reaction. Some of these substances also evolve into toxic gases when in contact with moisture, water or acids.

Examples: Calcium Carbide.

Class 5

Class 5.1: Oxidising agents

These are substances which, although in themselves not necessarily combustible, may, either by yielding oxygen or by similar processes, increase the risk and intensity of fire in other materials with which they come into contact. Oxidisers may cause fire when brought into contact with finely divided combustible materials and may burn with almost explosive violence.

Examples: Calcium Hypochlorite - Swimming Pool - Chlorinele Sodium Peroxide.

Class 5.2: Organic peroxides

These materials may be either liquids or solids. They support the burning of combustible materials. Under prolonged exposure to fire or heat, containers of these materials may explode. Many organic peroxides will burn rapidly and may react dangerously with other substances. Violent decomposition may be caused by traces of impurities such as acids. Decomposition of these substances may give rise to the development of toxic and flammable gases.

Examples: Benzoyl Peroxides, Methyl Ethyl Ketone Peroxide (MEKP)

Class 6

Class 6: Poisons

These are substances which are liable to cause death or serious injury to health if swallowed, inhaled or by skin contact. They are divided into toxic substances [Class 6.1 (a)] and harmful substances [Class 6.1 (b)]. These substances can be in either a solid or liquid form. Nearly all toxic substances develop into toxic gases when involved in a fire or when heated to decomposition.

Examples: Calcium Cyanide, Lead Arsenate.

Class 7

Class 7: Radioactive substances

This class includes materials or combinations of materials which spontaneously emit radiation.

Example: Radium


Class 8

Class 8: Corrosives

These are substances which are solids or liquids possessing in their original state, the common property of being more or less able to severely damage living tissue.

Many substances are sufficiently volatile to evolve vapour irritation to the nose and eyes. A few of these substances may produce toxic gases when decomposed by very high temperatures. Also some substances in this Class can be toxic. Poisoning may result if they are swallowed.

Examples: Hydrochloric Acid, Sodium Hydroxide.


Class 9

Class 9: Miscellaneous dangerous goods

These are substances and articles which present a danger not covered by the other classes.

Examples: Aerosols, Dry Ice, Asbestos.