Hi,
As an ex offshore medic I was well aware of the dangers of acute exposure to
Hydrogen Suphide but I didn't realise the effects of a chronic/long term
exposure, so the information you give below is interesting. Would people
tolerate working in such conditions - would they not be complaining about
the odour?.
Interesting.
Regards
Phil Kelley
-----Original Message-----
From: Richard Brown (ADMA HSED) [mailto:[log in to unmask]]
Sent: 02 July 2002 04:58
To: [log in to unmask]
Subject: Re: Hydrogen Sulphide in Dried Sewage Sludge
Working for an oil company I have had occasion to review the literature on
the health hazards relating to hydrogen sulphide. I have been unable to
find any thing that indicates that Hydrogen Sulphide has long term health
effects and have found no mention of effects on colour vision. Hydrogen
Sulphide is a highly soluble acid gas so much of the ill health effects
(oedema, conjunctivitis) are based on this, but symptoms disappear rapidly
once removed from exposure. There can be long term injury to the eye called
kerato-conjunctivitis, caused by repeated exposure to hydrogen sulphide at
above 20ppm, but this again emphasises the reactivity of hydrogen sulphide
as the impact is to the outer part of the eye. To affect colour vision
hydrogen sulphide would have to selectively attack the cones in the retina
or the part of the brain that interprets the signals from the cones.
You should also consider if dried sewage sludge is a significant source of
hydrogen sulphide. This would appear unlikely. The drying process will
drive off any existing hydrogen sulphide an as long as it stays dry the and
in the open air the anaerobic activity that creates hydrogen sulphide will
not begin again.
Hydrogen sulphide is likely to be present at some stages of sewage
treatment. Personal levels of exposure can be readily determined, either
by electronic meters or by draeger tubes. There are also diffusive samplers
that can measure the integrated dose over a shift and give an easily read
colour stain length.
Where there is hydrogen sulphide there is also mercaptans (organic
sulphides). These are much more toxic than hydrogen sulphide and more
difficult to measure.
Regards
Richard Brown
Occupational Hygienist
Health, Safety & Environment Division
Abu Dhabi Marine Operating Company
PO Box 303, Abu Dhabi, United Arab Emirates
Tel: +971-260-65325
Fax: +971-260-64997
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