My offical note to EC
From a photography web site I note that your organisation is reviewing the classification for Hydroquinone.
(ie as found in documents Risk Management Scope for 1,4-Benzenediol (Hydroquinone)Chemical Abstract Service (CAS)Registry Number:123-31-9 )
The exposure limits for dermal contact to me seemed to presume that a photo hobbyist would immerse their hands in a solution containing HQ. This is not a very standard practice.
The concentration of the HQ in such solutions also seems to be mis-represented.
HQ is frequently one of the developing agents of choice found in film developers, and in print developers.
Most photographers do not allow their skin in contact with film developer.
While it is possible to develop sheet film (4x5, 8x10 etc.) in a tray, and handle it with your fingers, it is a more common practice to develop sheet film in a deep tank and handle the film via hangers the film is suspended from.
The much more common roll film formats (35mm, 120 format, etc) is commonly processed by rolling the film on a reel, placing the reel in a light tight trapped tank, and pouring the solutions in and out while the lights are on. Occasionally some drops of solution may contact the skin while solutions are being poured in and out of the tank. .
B&W Print developer is more common form in which one might contact HQ. A typical print developer stock solution contains about 12g of HQ, and it is typically diluted at a rate of 1:1 to 1:3 with water. The prints are typically moved from tray to tray by using tongs. When multiple prints are stuck together in a tray, tongs may not have the grip to separate them, and an un-gloved pair of fingers may be needed to separate the sheets.
The reason most photographers keep clear of the wet developer solutions is that they are typically rather alkaline, and therefore a skin irritant irrespective of the presence of any developing agents.
The developer solution with the highest concentration of HQ that I use uses 22g/L, and is used to process lithographic films. It is also quite alkaline, achieved by the use of sodium hydroxide as the alkaline agent. It is not what one wishes to soak you hands in, as though you are being intoned to do so by Madge the manicurist.
For an insight into hydroquinone as present in photographic developer solutions, I would recommend the darkroom cookbook by anschell and troop.
Please advise me of any additional information that you may require. I would be interested in getting notices of how the review of this chemical is progressing.
Mike Wilde
