suspected mycobacterial infections but an exposure time of 60 - 75 minutes is
suggested for M.avium intracellulare (17,18). Furthermore, Hanson et al (7,16)
have shown that thorough cleaning of endoscopes removed 3 - 5 log10 of
Other aldehydes are available often in combination with other disinfectants. Such
combinations are designed to augment antiviral and antibacterial activity and to
reduce adverse reactions amongst staff. 'Gigasept' (succine dialdehyde and
formaldehyde) is the most widely used. It is, however, inferior in its microbicidal
activity to glutaraldehyde at use concentration and longer contact times are
required. In addition, toxic reactions have occurred in exposed individuals. There
would seem little advantage for this agent over 2% glutaraldehyde.
The major problem associated with the use of aldehyde disinfectants is that of
adverse reactions amongst workers in endoscopy (2). Such reactions present as
dermatitis (which may be generalised) (22), conjunctivitis (23), nasal irritation
(24) and asthma (.25,26). These problems have been long recognised by the
Health and Safety Executive.
The Health and Safety at Work Act 1974 requires employers to ensure, as far as
is reasonably practicable, the health, safety and welfare of all employees. The
Act also requires employees to comply with the precautions established to
ensure safe working. The Control of Substances Hazardous to Health
Regulations 1994 (COSHH) require employers to assess the risks to the health
of staff by exposure to hazardous chemicals such as glutaraldehyde, to avoid
such exposure where this is reasonably practicable, and otherwise to ensure
adequate control. Engineering methods of control must be used in preference to
personal protective equipment. Failure to comply with COSHH, in addition to
exposing staff to risk, constitutes an offence and renders the employer liable to
penalties under the Health and Safety at Work Act 1974. There are specific
criteria relating to exposure levels. These are defined in terms of average
occupational exposure standard (OES) and maximum exposure level (MEL).
'OES' is the atmospheric level down to which exposure must be reduced. Some
leeway is allowed to employers as long as a schedule is put in place until
required levels are actually achieved. 'MEL' is the exposure which must not be
exceeded and employers must reduce exposure to below this level.
Glutaraldehyde currently has an OES of 0.2 ppm (0.7 mg/m3). MELs at 0.02 ppm
(8-hour time weighted average TWA)) and 0.05 ppm (15 minute reference
period) would lead to an improvement in the overall standards of control if this is
reasonably practicable .
The Health and Safety Commission's Advisory Committee on Toxic Substances
(ACTS) has recommended that:
1. Maximum exposure limits for glutaraldehyde should be established at:
i 0.02 ppm as an 8-hour TWA;
ii 0.05 ppm over a 15 minute reference period;
and that these limits should attract a 'Sen' (sensitiser) notation.
2. Subject to the Commission's approval, the existing OES for glutaraldehyde
will be withdrawn in the 1998 issue of EH40; and
3. HSE will publish guidance on the control of exposure in 1999. The