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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

contaminating organisms.

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

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