Chemical Safety

Introduction

          Chemicals have become a part of life, sustaining many of our activities, preventing and controlling many diseases, increasing agricultural productivity. However, one cannot ignore that many of these chemicals may, especially if not properly used, endanger our health and poison our environment.

          It has been estimated that approximately one thousand new chemicals come onto the market every year, and about 100000 chemical substances are used on a global scale.

More substances and rising production mean more storage, transport, handling, use and disposal of chemicals. The
whole life cycle of a chemical should be considered when assessing its dangers and benefits. No chemical substance can cause adverse effects without first entering the body or coming to contact with it. Chemicals are injurious to health because of their toxic properties.

Harmful effects of Chemicals on Human Body

• Chemicals can cause asphyxia or suffocation.
• It causes irritation to respiratory tract or other vital organs like liver, kidney, etc.
• Some chemicals cause semi-consciousness or unconsciousness.

There are four main ways that is routes of exposure, for chemical substances to enter the human body:

• Inhalation (breathing in): Most chemicals used at the place of work may be dispersed into the air to form dust, mist, fumes, gas and vapor and can then be inhaled. In this way also workers who are not actually handling them but stay within the reach can be exposed to a mixture of chemicals from various sources.
• Absorption (through the skin or eyes): Handling chemical substances without proper protection exposes the worker to the risk of absorbing harmful amounts of chemical through the skin. This usually happens when handling the chemical in liquid form. Dust may also be absorbed through the skin if it is wetted by, for instance, sweat.
• Ingestion (eating, swallowing): Eyes may also absorb chemical substances, wither from splashes or from vapors. Dangerous chemicals can enter the body through ingestion as gases, dusts, vapors, fumes, liquids or solids. Inhaled dust may be contaminated by dirty hands. Eating, drinking and smoking should be prohibited at a place of work where dangerous chemicals are used.
• Transfer across the placenta of a pregnant women to the unborn baby.

 Risk Effects of Chemicals

•     Acute effects – The effects may be acute, after a short exposure an immediate effect may be experienced. Eg: NB3, acid, bases.
•     Chronic effects – Chronic effects usually require repeated exposure and involve a delay between the first exposure and appearance of adverse health effects. Eg: Toxicity by Chromium.
•         Local effects – Hazardous substances may cause local effects. Acute local effects may include corrosive injuries from acids and bases or lung injuries from inhaled gases such as ozone, phosgene and nitrogen oxides.
•            Systemic effects – Many other gases cause adverse effects only after they have been inhaled repeatedly over a long time period. Low concentrations of a gas may also be effective in this way. A persistent irritation of the respiratory system can arise from exposure to gases such as sulphur oxides, hydrogen fluoride and hydrogen chloride. Eg: CO inhalation, H₂S inhalation, Benzene and Aniline poisoning, Methanol poisoning.

Multiple Effects of Chemicals in Industry

• Fire Hazards – Combustible and flammable solids, liquids and gases cause fire hazards.
• Accidental release of toxic or corrosive chemicals – Toxic or corrosive materials can suddenly leak as a result of mechanical failure, in advance or due to mishandling on a part of worker thus causing serious accidents.
• Explosions – Due to bad housekeeping / storage or handling or spontaneous effects, accidents can occur with explosive mixtures.
• Environmental Pollution – It is due to inadequate or defective waste disposal or treatment method.

Chemicals may be classified as:

• Asphyxiants: Any chemical which can cause breathing trouble is called Asphyxiants. Some asphyxiants are CO₂, Nitrogen, Hydrogen, etc. Chemical asphyxiants are CO, Hydrogen Cyanide, etc.
• Irritants: Any chemical that can cause irritation to the eyes, skin, respiratory tract are called Irritant. Primary irritants are ammonia, sulphur dioxide, chlorine, etc. Secondary irritants are Hydrogen Sulphide, Carbon-Di-Sulphide.
• Anaesthetics: Any chemical that can cause semi consciousness is called Anaesthesia. Primary are gasoline, ether, alcohol, etc. Secondary anaesthetics with liver toxicity are Carbon Tetra-Chloride and with Haemopoitic toxicity are Benzene, Naphthalene, etc.
• Organic Group: Aromatic Hydrocarbons, Aliphatic Hydrocarbons, coal tar derivatives, phenol, cresol, etc.
• Inorganic – Lead, Arsenic, Chromium, Manganese, Stibine, etc.
• Organic Metallic – Tetra Ethyl Lead (TEL), etc.

Control measures for hazardous chemicals to prevent accidents:

          It is also called HAZMAT code (Hazardous Material) and UN Hazard class.

1. Substitution – Consider substituting the chemical to a less hazardous chemical to reducing chemical hazards. For example, replacing Benzene with Toluene.

2. Store minimum quantities – Never stock up more than a year’s supply of chemicals. Amounts of chemicals that can be used up in 3 months are recommended. Do not purchase larger quantities than needed, it will increase the potential hazards, take up valuable space and could result in a costly disposal problem.

3. Chemicals in the storage area – Store as little chemical in the work area as possible. Chemicals should be put back into the storeroom at the end of the workday.

4. Access – Unauthorized access to the storage areas must be prevented. Security may be appropriate.

5. Proper shelving – Shelving should be more than strong enough to support the weight of chemicals and firmly secured to the wall or ceiling. Shelving should be made of the appropriate chemically resistant materials. Shelves should not be made of unfinished wood. Ensure that shelves are adequately spaced to allow for easy access.

6. Proper placement – Containers of chemicals should not be crowded. Accessing one container should not require the movement of other containers. Containers of chemicals should not be stacked on top of one another. Store chemicals below eye level (at the chest level) and above knee level but avoid storing chemicals on the floor. Solid materials placed on higher shelves than liquids and heavier containers placed on lower shelves than lighter containers.

7. Labelling – All chemicals must properly be labelled with information in its contents. All appropriate information concerned with chemicals e.g. the date received, expiration date, etc. Labels should be waterproof and easily legible. Periodically check to ensure that labels are not missing/fallen off.

Class 1        Explosives.

Class 2        Flammable Gases.

Class 3        Flammable Liquids.

Class 4        Flammable Solids.

Class 5        Oxidizing Peroxides.

Class 6        Poisoning and Infections.

Class 7        Radioactive materials.

Class 8        Corrosives.

Class 9        Miscellaneous Eg. Chemicals residue.

8. Access to information – Store must have accessible database of chemicals. MSDS for every chemical stored and used must be easily accessible. Floor plans should be made available to the local fire department.

9. Neatness – The chemical storage area should not double as a general storage area. Machines, tools, manufactured goods should not be kept in the storage room. Aisles and exits must be clear and unobstructed at all times.

Chemical Hazard

From hazard due to chemical.

Examples of Chemical Hazards and Effects

Solid

Liquid

Gases

Toxic Measurements

• Lethal Dose 50 (LD50):  It is a precise dose of a substance via any route, which is expected to cause death of 50% of an entire defined experimental animal population. The result is expressed in mg. per Kg. body weight.
• Lethal Concentration (LC50):  This is expressed for act toxicity on inhalation. It is that concentration of the substance in air in the form of vapor, mist or dust which administered by continuous inhalation by both male and female adult rats for 1 hour is most likely to cause death within 14 days in ½ (50%) of the animal tested.
• Immediate Danger to Life and Health (IDLH):      IDLH is the lowest air borne concentration of substance which can cause death or can seriously affect the health of a person. It is usually expressed in mg/cm³ or PPM.
• Maximum Allowed Concentration (MAC):  MAC is the concentration of toxic substances which must not be exceeded or violated even for a very short period of time.
• Ceiling Value (C): Ceiling value is the maximum concentration of a toxic material which the workmen can tolerate or withstand for 8 hours in a day while working in the atmosphere charged with the contaminant.

Control Measures

Why control is important?

To prevent exposure of hazardous chemical with workers.

What is control?

Any procedure device uses to keep hazardous liquids, gases or solids from contacting workers at harmful levels.

Hierarchy of Control

Storage

1. Proper storage and handling.
2. Procure only as per the requirement, in time and better supply chain management will prevent accumulation of raw materials.
3. Storage areas must be separated from processing/ handling areas.
4. Chemical should not be in process areas only before they should be brought to process.
5. Unauthorized entry to be prevented to storage area.
6. Proper shelving strong enough to be used.
7. Removal and stacking should be done by trained personal.
8. Proper placement. (should not be kept on the bare ground).
9. Temperature & pressure.
10. Operation & process.
11. Education & training.
12. Data collection.
13. Maintenance.
14. PPE’s.