JSP 375 Vol 2 

MoD Health & Safety Handbook 

52  If, however, the substances in use are particularly toxic, carcinogenic, have a specified MEL or the 

information supplied by the supplier does not match with other sources of authoritative guidance such as 

HSE guidance notes etc. then extreme caution will be warranted. These cases should always be 

referred for specialist advice unless you are absolutely certain that exposure is not significant. It is also 

important to use your own judgement and look for obvious discrepancies. For example: if all the control 

measures recommended by the supplier are in place but there are obvious problems such as fine dust 

deposits on people or surfaces, particles visible in the air, complaints of discomfort or ill health amongst 

the workforce then you should seek specialist advice. So your answer to Question (a) would therefore 

be No and CONCLUSION 5. 

(b) Would the process present significant risks to health if no controls were in place? 

53  Assuming that your information sources are satisfactory you should now be able to decide whether 

the health hazards posed by the products are significant. This requires a balanced judgement combining 

your conclusions on work practices with the properties of the substance(s). From this information it 

should be apparent in most cases whether the potential consequences of exposure are serious or not. 

Risk phrases such as  may cause death  or  may cause cancer  are clear indicators of hazards that must 

be taken seriously. Conversely phrases such as prolonged contact may cause minor skin irritation will 

generate little concern if the exposure is of limited duration. As a general principle if a substance is 

capable of causing adverse health effects at the expected exposure levels and a realistic route of entry 

can be identified then the risks to health will be significant. 

54  An example may help to clarify these concepts. Consider two applications of the solvent 1,1,1 

Trichloroethane.  Because of its affect on the earth s ozone layer, we are no longer able to use 1,1,1 

Trichloroethane, but we have continued to use the example here because it relates to situations with 

which many will be familiar. 

54.1 

This substance was used as a solvent in Typists correction fluid and the symptoms of 

exposure were potentially significant [Harmful by inhalation or if swallowed.  Avoid contact with skin 

and eyes]. However, the volume used to correct a typing error coupled with the limited exposure 

time indicated no significant risks to health by inhalation.  The suppliers  data sheet would also 

show that ingestion can cause serious problems but realistically we can discount this route of entry, 

as no normal person would drink the fluid and the prospect of accidental ingestion was remote. 

On the other hand... 

54.2 

The use of 1,1,1 Trichloroethane as an industrial degreasing agent presented the same 

potential problems as the correction fluid [Harmful by inhalation or if swallowed.  Avoid contact with 

skin and eyes]. However, if the solvent was applied with a rag to a large aircraft component it gave 

an entirely different conclusion regarding the risks to health.  Clearly, inhalation of significant 

amounts could have become a real possibility because the volume of solvent was so much greater, 

the surface area over which it was applied was much larger and the exposure time would have 

been longer.  Skin contact was also likely to present a significant risk to health, while if eating, 

drinking or smoking occurred in the workplace then the risk of accidental ingestion also became a 

major consideration. 

In this case the risks to health are very serious 

55  In both examples on the potential risks to health, no mention has been made of control measures.  

Control measures must be considered separately otherwise serious potential health risks will be masked 

by preventative methods and the dangers posed by a plant breakdown or failure of controls may not be 

appreciated. 

56  When answering "Would the process present significant risks to health if no controls were in 

place?" several factors must be taken into account: 

56.1 

What is the potential of a substance to cause harm? This can be judged from the 

symptoms of over exposure and whether the substance has any classification which makes it 

particularly noteworthy. E.g. is it a carcinogen, does it have a maximum exposure limit etc. 

Leaflet 5 Annex F 

Page 8 

 April 

2003