Chemical Hazards
Average annual world production of chemicals amounts to an estimated 400 million tones. There are between 5 to 7 million known chemicals, however, only 70,000 to 80,000 are on the market, with 1,000 or so being produced in substantial quantities. In North America around 1,000 to 1,200 are produced annually (50 % are polymers).In Western Europe, some 150 to 200 new substances are registered each year. Of the 70,000 to 80,000 chemicals only 5 to 10% ( i.e., 500 to 7,000 should be considered hazardous; 150 to 200 of these are carcinogenic.
Hazardous Substances are used in many workplaces and take many different forms. Solids, liquids, gases, mists and fumes can be present in the workplace.
Chemical hazards are dependent on:
- Amount
- Concentration
- Time of exposure
- Mode of entry to the body
- Age
- Sex
- Health status
- Resistance of the exposed workers
The effects of chemical agents are as follows:
- Asphyxiation
- Systemic intoxication
- Pneumoconiosis
- Carcinogens
- Irritation
- Mutagencity
- Teratogenicity
Dangerous Chemical Substances
Many dangerous substances are used in industry, commerce, agriculture, research activities, hospitals and teaching establishments.
The classification of dangerous substances is based largely on the characteristic properties of such substances and their effects on man. Legislation on this subject also requires the provision of a specific pictorial symbol on any container or package.
The following terms are used in the classification of dangerous substances in the classification, packing and labeling of dangerous substances regulations 1984.
A. Corrosion
B. Oxidizing
C. Harmful
D. Very toxic and toxic
E. Irritant
F. Highly flammable
G. Explosive
A. Corrosive
Hazard: Living tissues as well as equipment are destroyed on contact with these chemicals.
Caution: Do not breathe vapors and avoid contact with skin eyes, and clothing
B. Oxidizing
Hazard: ignite combustible material or worsen existing fire and thus make fire fighting more difficult.
Caution: Keep away from combustible material. Restrict smoking in that area.
C. Harmful
Hazard: Inhalation and insertion of or skin penetration by these substances is harmful to heath.
Caution: Avoid contact with the human body, including inhalation of vapors and in cases of malaise consult doctor.
D. Very toxic and toxic
Hazard: The substances are very hazardous to health whether breathed, swallowed or in contact with the skin and may even lead to death.
Caution: Avoid contact with human body, and immediately consult a doctor in case of malaise.
E. Irritant
Hazard: May have an irritant effect on skin, eyes and respiratory organs
Caution: Do not breathe vapors and avoid contact with skin and eye
F. Highly Flammable
Hazard: Substances with flash point less than 60'C or 140'F
Caution: keep away source of ignition.
G. Explosive
Hazard: Substances which may explode under certain condition
Caution: Avoid shock, friction, sparks and heat.
Chemical Hazards Evaluation
- Toxicity assessment
- Work activity/risk assessment evaluation
- Assessment of controls effectiveness to block routes of entry
- Exposure monitoring
- Recommendations for improvement
Chemical Hazards: Exposure Monitoring
- Special instruments - infrared absorption, photoionization, gas Chromatography
- Detector tubes
- Air sampling and lab analysis
- Professional judgment
Chemical Hazards: Engineering Controls
- Substitution (use lower toxicity materials)
- Enclose processes and otherwise engineer for low emission / low risk
- Provide local exhaust to remove airborne agents
- Local exhaust ventilation
- Need to have even air flow for hoods
- Need to design for adequate capture velocity -usually about 100 feet/minute
- Need sufficient make up air
- Use ACGIH Ventilation Manual for design
- Reduce exposure time
- Better procedures
- Training
- PPE - gloves, face shields, respirators
- Remote Operation
How to control these toxic substances from endangering ourself?
ReplyDeleteBy following the handling procedure correctly and always wear personal protection equipment all the time while handling those substances. You also can substitute or change the material and working practice to one less hazardous.
DeleteWhy some substances are hazardous?
ReplyDeleteBecause the content of some substances can cause harm to us when in direct or indirect contact
DeleteWhere does this toxic substances normally kept?
ReplyDeleteThose substances are kept in a different place according to its characteristics.
DeleteSubstances that have a high degree of combustibility that they are designated flammable must be stored in approved fire-resisting safety cans or cabinets. Avoid storing flammables in direct sunlight or near other heat sources; eliminate all sources of ignition (heat, sparks, or open flames). Keep the area dry and cool. Use internally ‘spark-free’ refrigerators designed for chemical storage when chemicals require cold storage (see SDS). Most flammable vapors are heavier than air and will settle low to the ground where they are free to do so. Provide adequate ventilation to prevent the accumulation of large amounts of vapor.
Inorganic mineral acids (e.g. nitric, sulfuric, phosphoric, chromic, hydrochloric and perchloric acids), store in a labelled ventilated corrosive storage cabinet if possible separated from flammable and combustible materials.
Poisons and toxic chemicals such as inorganic poisons (e.g. mercury, heavy metals and their salts) or organic poisons (e.g. phenol, sodium azide, pharmacological drugs*). These regulated and reportable poisons must be managed in such a way as to be able to comply with current legislation and should be kept under lock and key,
Toxic chemicals that are acid-sensitive, such as cyanides and sulphides, need to be stored in a separate location from acids or protected from contact with acids. Store poisons and toxic
substances according to the nature of the chemical using appropriate security where necessary e.g. locked cabinets with strict key controls.
Volatile poisons e.g. poisons, toxics, and carcinogens, such as carbon tetrachloride, chloroform, dimethylformamide, dimethyl sulfate, formamide, formaldehyde, halothane, mercaptoethanol, methylene chloride, and phenol must be stored in a ventilated cabinet.
Non-volatile liquid poisons e.g. acrylamide solutions, coomassie blue stain, diethylpyrocarbonate, diisopropyl fluorophosphate, uncured epoxy resins, ethidium bromide, triethanolamine. This group contains carcinogens and highly toxic chemicals can store in a normal cabinet, preventing contact with other materials
* the storage of certain substances are subject to control under The Misuse of Drugs Regulations and the Drug Precursor Regulations and may be required to be kept secure under
lock and key