Control measures 2 - Substitution

Substitution

If a particular dangerous chemical or work process cannot be completely eliminated, then try to replace it with a safer substitute.
It is not easy to find "safer" chemical substitutes (in fact, no chemical should be considered completely safe). It is important to review every year the current reports on the chemicals used in the workplace because chemicals considered to be "safer" substitutes today may not be considered safe in the future.

When one has to look for safer substitutes, try to choose a less volatile (volatile liquids vaporize, or evaporate easily) instead of a highly volatile one, choose a solid instead of a liquid, etc. For example, many dry, dusty powders are also available in brick, pellet, paste, flakes, oil damped powders, and other forms that create less dust when handled, and reduce the chance of inhaling the dust. Many plastics and rubber industry chemicals can also be supplied in dust-suppressed forms. These materials can be more expensive to purchase but they are safer for workers to handle and can be cheaper when other costs are considered, such as the cost of ventilation to control dust, personal protective equipment, etc. The figures demonstrate the dust/fume of a hazardous chemical, this chemical has been substituted by a chemical which do not have dust/fumes.

Other examples of substitution include using:

  • Less hazardous solvents instead of toxic ones dichloromethane or fluorochlorohydrocarbon instead of carbon tetrachloride; and toluene, cyclohexane or Ketones instead of benzene).
  • Detergent plus water-cleaning solutions instead of organic solvents;
  • Freon instead of methyl bromide chloride as a refrigerant;
  • Leadless glasses in the ceramics industry;
  • Leadless pigments in paints;
  • Ozone in place of Chlorine in swimming pools;
  • Synthetic grinding wheels (such as Aluminum oxide, Silicon carbide) instead of sandstone wheels.

Are substitute materials always safer than the original hazard?
No. There are examples where a material that was thought to be safer was found to be as bad as, or worse than, the original hazard. A classic example is asbestos. Fiberglass has been used as a substitute for asbestos; however, it is now known that fiberglass is also a hazardous material and is not a completely safe substitute for asbestos. A substitute may be better than the original hazard, but that does not mean it is safe.

Where one can get information on substitute materials?
Material Safety Data Sheet (MSDS) is the best source of getting information about the hazardous chemical. Manufacture, Storage and Import of Hazardous Chemicals (MS and IHC) Rules 1989 and subsequent amendments. Provide schedule 9 for information on the MSDS is also available with other sources are as shown in the figure below.

Protective measures are important when working with all chemicals, even if one is using a "safer" substitute.
Can dangerous work processes be substituted with safer processes? Yes. Changing the way of job is another form of substitution. For example, vacuuming up dust instead of sweeping it, or using "membrane cell by mercury electrodes" to control mercury pollution is safer way in chlor-alkali industry."Wet methods" mean spraying water over a dusty surface to keep dust down, or mixing water with the material used to prevent dust from being created. These methods reduce the amount of dust in the air.

The toxic fumes should be scrubbed by water or dilute chemical solution by spraying through scrubbers as shown in the figure below.

Other examples are:

  • electric motors instead of diesel or petrol engines to eliminate hazardous exhaust fumes;
  • "dust-free" cutting or grinding equipment;
  • dip or brush instead of spray painting;
  • covered containers to carry materials which produce air contaminants.

Use a vacuum cleaning when cleaning up toxic dust. Never sweep toxic dust-sweeping puts the dangerous dust back into the air where you can breathe it.

 

Remember
  1. If a dangerous chemical or work process cannot be eliminated, then try to replace it with a safer substitute. Not all substitute materials are really "safer" - they may be better than the original hazard but can still be dangerous.
  2. Protective measures are important when working with all chemicals, even if you are using a "safer" substitute.

 

 
Locations of visitors to this page