Re fit testing

The following is taken from a document produced by the British Association of Dermatologists on occupational skin disease during the coronavirus pandemic.

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Contact urticaria was seen in a nurse in Wales being “fit tested” for a face mask. The chemical used for the testing is denatonium benzoate, which has been previously reported to cause urticaria and asthma.

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Worth checking your safety data sheet?

I've always used saccharine in the first instance as Bitrex is so unpopular, with Bitrex as the second resort for those that don't detect the saccharine.

https://www.bitrex.com/trade-retail/msds-and-specifications

Slightly out of date CLP SDS but classifies as Skin Irrit 2 - H315, Eye Dam 1 - H318

Yes, but contains more than one constituent recognised by dermatologists as a skin sensitiser but which, for some reason, do not appear to fit the requirement for them to be classified as H317. Perhaps another reason why relying on safety data sheets for the information for a  COSHH risk assessment might not be the way to go.

As always you do the risk assessment using whatever information is to hand. If EH40 says it’s a skin sensitisers that means it might cause problems if the person is a) susceptible and b) has repeated exposure. You can’t tell if a person is susceptible but you can always ask. You could arrange allergy testing but that might not be classed as reasonably practicable of you have loads of people and you only expose them to the Bitrex once a year or how often you do the face fit testing.

If you decide that you don’t want to risk people developing urticaria, which is a kind of skin rash your options are:

• Don’t do face fit testing- of course you should be doing face fit testing but decide how often you need to do it or look at alternative RPE that does not require face fit testing or good back to that original COSHH risk assessment  and see if you can use other, better controls such as LEV.
• If you do a lot of face fit testing it might make sense to invest in a quantitative testing kit rather than the qualitative kit
• Or do what Kate says- reserve the Bitter solutions for those people who can’t taste the sweet solutions. The SDS for saccharin seems to indicate that it poses a minimal risk but there has been evidence that it might cause allergic reactions, which of course might be an issue with repeated exposure.

So you takes your money and makes your choice.

Allergy testing for skin reactions is not something that should be done as a precautionary measure. With both types of common allergy test (patch test for allergic contact dermatitis, prick test for allergic contact urticaria) there is always a risk of the person becoming sensitised. As the process of sensitisation takes days, your test would not reveal this but would return a negative result in someone not already sensitised.

Sensitisation is asymptomatic so you would not be aware that this has happened. However, when next exposing that person to the sensitiser they might then respond with an allergic reaction.

There are tests for type I immune response (allergic contact urticaria) which involve taking a blood sample and analysing this (ELISA, RAST) but these are expensive and not all that reliable.