Element 7 cheat sheet: Chemical and biological agents

7.1 Hazardous substances

• Chemical agents occur as dusts, fibres, fumes, gases, mists, vapours and liquids.
  • ('text', 'Chemical agents occur as dusts, fibres, fumes, gases, mists, vapours and liquids.')
• Acute effects appear quickly after a short exposure (for example a chemical burn or a headache).
  • ('text', 'Acute effects appear quickly after a short exposure (for example a chemical burn or a headache).')
• Health hazard classes used in the classification of chemicals: acute toxicity; skin corrosion or irritation; serious eye damage or irritation; respiratory or skin sensitisation; germ cell mutagenicity; carcinogenicity; reproductive toxicity; specific target organ toxicity (single and repeated exposure); and aspiration hazard.
  • ('text', 'Health hazard classes used in the classification of chemicals: acute toxicity; skin corrosion or irritation; serious eye damage or irritation; respiratory or skin sensitisation; germ cell mutagenicity; carcinogenicity; reproductive toxicity; specific target organ toxicity (single and repeated exposure); and aspiration hazard.')

Terms: Acute effect, Chronic effect

Tip: Know the difference between acute and chronic, with an example of each.

7.2 Assessment of health risks

• Substances enter the body by inhalation, ingestion, absorption through the skin and injection (for example needlestick).
  • ('text', 'Substances enter the body by inhalation, ingestion, absorption through the skin and injection (for example needlestick).')
• An assessment considers the substance and its hazards, the form it is in, the routes of entry, how much exposure there is and for how long, who is exposed and the effectiveness of existing controls.
  • ('text', 'An assessment considers the substance and its hazards, the form it is in, the routes of entry, how much exposure there is and for how long, who is exposed and the effectiveness of existing controls.')
• Sources of information are product labels and safety data sheets (SDS).
  • ('text', 'Sources of information are product labels and safety data sheets (SDS).')
• The information has limits: it may be general, may not cover mixtures or the way the substance is actually used, and may not be up to date.
  • ('text', 'The information has limits: it may be general, may not cover mixtures or the way the substance is actually used, and may not be up to date.')
• Monitoring of hazardous substances (for example air sampling) shows exposure levels, but it only gives a snapshot of a particular time and place.
  • ('text', 'Monitoring of hazardous substances (for example air sampling) shows exposure levels, but it only gives a snapshot of a particular time and place.')

Terms: SDS

Tip: Remember the four routes of entry.

7.3 Introduction to occupational exposure limits

• An occupational exposure limit is the airborne concentration of a substance to which workers may be exposed without being expected to suffer harm.
  • ('text', 'An occupational exposure limit is the airborne concentration of a substance to which workers may be exposed without being expected to suffer harm.')
• Long-term limits relate to an average over a working day (usually 8 hours, a time-weighted average).
  • ('text', 'Long-term limits relate to an average over a working day (usually 8 hours, a time-weighted average).')
• Limits have limitations: they do not apply to all substances; they do not cover skin absorption unless indicated; they assume healthy adults; individuals vary; and they do not allow for combined exposure to several substances.
  • ('text', 'Limits have limitations: they do not apply to all substances; they do not cover skin absorption unless indicated; they assume healthy adults; individuals vary; and they do not allow for combined exposure to several substances.')

Terms: TWA

Tip: A reading below the limit does not mean the exposure is safe, only that it meets a standard.

7.4 Control measures

• The first aim is to prevent exposure. If that is not reasonably practicable, control it adequately. Common measures:
  • Eliminate or substitute with a less hazardous substance
  • Change the process
  • Enclose the process
  • Local exhaust ventilation
  • General ventilation
  • Reduce the number of people exposed and the time
  • Good housekeeping and cleaning
  • Hygiene facilities and procedures
  • Storage and labelling
  • Training and information
  • PPE and respiratory protective equipment (RPE) as a last resort
  • Health surveillance
• Substances that can cause cancer, asthma, or genetic damage that can be passed from one generation to the next need extra controls, for example preventing exposure rather than only controlling it, tighter access, enclosed systems and health surveillance.
  • ('text', 'Substances that can cause cancer, asthma, or genetic damage that can be passed from one generation to the next need extra controls, for example preventing exposure rather than only controlling it, tighter access, enclosed systems and health surveillance.')

Tip: PPE and RPE always come last.

7.5 Specific agents

• Asbestos (excluding removal and disposal): found in older buildings in insulation, boards, roof sheets and pipe lagging.
  • ('text', 'Asbestos (excluding removal and disposal): found in older buildings in insulation, boards, roof sheets and pipe lagging.')
• Blood-borne viruses (such as hepatitis B, hepatitis C and HIV): spread by blood and some body fluids, for example through sharps injuries.
  • ('text', 'Blood-borne viruses (such as hepatitis B, hepatitis C and HIV): spread by blood and some body fluids, for example through sharps injuries.')
• Carbon monoxide: a colourless, odourless gas from incomplete combustion, found where fuel burning appliances or engines are poorly ventilated.
  • ('text', 'Carbon monoxide: a colourless, odourless gas from incomplete combustion, found where fuel burning appliances or engines are poorly ventilated.')
• Cement: wet cement is alkaline and can cause burns and dermatitis; dust irritates the eyes and lungs.
  • ('text', 'Cement: wet cement is alkaline and can cause burns and dermatitis; dust irritates the eyes and lungs.')
• Legionella: bacteria that can grow in water systems (cooling towers, hot and cold water systems) at temperatures roughly between 20 and 45 degrees C.
  • ('text', 'Legionella: bacteria that can grow in water systems (cooling towers, hot and cold water systems) at temperatures roughly between 20 and 45 degrees C.')
• Leptospira: bacteria spread in the urine of rats and other animals, causing leptospirosis (Weil's disease).
  • ('text', "Leptospira: bacteria spread in the urine of rats and other animals, causing leptospirosis (Weil's disease).")
• Silica: dust from sand, stone, concrete and bricks.
  • ('text', 'Silica: dust from sand, stone, concrete and bricks.')
• Wood dust: from sawing and sanding.
  • ('text', 'Wood dust: from sawing and sanding.')

Tip: For each agent, learn a health effect, a typical place and a control.