Advice to Users
Extensive toxicological tests have
been conducted on Saffil alumina fibre and all results lead to the conclusion
that Saffil fibre is unlikely to have any significant adverse biological effect.
Nevertheless, we recommend that atmospheric exposure be controlled to a Maximum
Exposure Limit (MEL) of 5 mg/m 3 total dust or 2 fibres/ml, whichever is the
more stringent, each 8-hour Time Weighted Average, according to the COSHH
(Amendment) Regulations 1990. (Reference 1). Experience shows that the
gravimetric standard has proved the more appropriate for operations involving
Saffil fibres. If it is necessary to apply the fibre count method then fibre
clumping on the filter may be a problem.
Under the COSHH Regulations for substances with an MEL,
exposures should not exceed the MEL and should be reduced so far as is
reasonably practical below the MEL. In our experience, even very severe handling
of Saffil fibre products only transiently produces dust concentrations exceeding
5 mg/m3 but, where this does occur, we recommend that ventilation be provided or
effective dust masks be worn.
Practical experience has shown that 'Saffil' fibre may cause
temporary irritation of the skin, nose and throat. It is recommended therefore
that gloves be worn by operators handling the fibres repeatedly, that clothing
should be loose around the neck and wrists and that precautions be taken (as
described in the previous paragraph) to avoid breathing dusts. After handling,
exposed skin areas should be washed with water and work clothing should be
washed separately. For further advice on handling 'Saffil' fibre see Reference
2.
Design and Specification
Any insoluble fibrous
material may have the potential to induce adverse health effects. 'Saffil' fibre
has been carefully designed and is produced to a specification intended to
minimise any biological activity. The basic material (alumina) does not produce
fibrosis in powder form and fibre diameter is carefully controlled within a
narrow range to minimise the number of sub-micron fibres (considered to have the
potential to induce fibrosis and mesothelioma) and also to minimise the
proportion of fibres which are respirable (likely to penetrate into the depths
of the lung). At the same time the proportion of fibres greater than 5 microns
diameter is minimised to reduce its irritant potential.
Results of Testing
Saffil fibre produced to the above
specification has been subjected to an extensive series of animal and other
tests to verify the design assumptions and to determine any toxic potential.
These tests are summarised below:
1 Intraperitoneal Injection and Cytotoxicity
Tests
Saffil fibres were injected into the peritoneal (abdominal) cavity
of rats and the animals maintained for observation for up to one year. The
reaction to Saffil fibre was quite distinct from the fibrotic reaction produced
by asbestos and indicates a lack of fibrogenic potential. The results of two in
vitro tests for fibrogenic potential were also negative.
2 Intratracheal Injection
Saffil fibres were
injected into the lungs of rats via the windpipe and the animals maintained for
the remainder of their lifespan. No signs of fibrosis or cancer associated with
the treatment were seen, although rats injected with asbestos as a positive
control showed a number of cases of lung fibrosis.
3 Intrapleural Injection
Saffil fibres were injected
directly into the pleural space of rats (the space between the rib cage and the
lung tissue) and the animals maintained for the remainder of their lifespan. Two
studies on very similar Saffil fibre samples showed no signs of pleural fibrosis
or mesothelioma, while asbestos treated control rats showed the expected
incidence of both. This extremely severe test (in which false negatives are
unknown) indicates that 'Saffil' fibre probably lacks one or more of the
fundamental characteristics necessary for mesothelioma induction, as well as
providing further evidence of the absence of fibrogenic
potential.
4 Inhalation
Rats were exposed to atmospheres containing the
maximum achievable levels of 'Saffil' fibre for seven hours/day, five days/week
for 18 months and then maintained for the remainder of their lifespan. No lung
fibrosis or lung cancer were seen although asbestos treated control rats showed
the expected incidence of both. The minimal lung response seen in Saffil fibre
treated rats was typical of a 'nuisance particulate' (ACGIH definition (3)).
Extensive investigations showed no other treatment related effects. This study
provides confirmation by the route of exposure most relevant to man of 'Saffil'
fibre's lack of toxic potential.
5 Ingestion
Feeding trials on
rats have been conducted with Saffil fibres and these have shown no evidence of
fibre penetration of the gut or accumulation of fibre in any part of the body. A
lifetime feeding study has produced no evidence of any effects due to Saffil
fibre at levels up to 2.5% in the diet.
Summary
Saffil fibre
was designed to minimise biological effects and the extensive series of tests
described above confirms that exposure to Saffil fibre is unlikely to have any
significant toxic effect in the lung. It can be irritant to the skin, nose and
throat.
References
Control of Substances Hazardous to Health
(Amendment) Regulations 1990. (Effective 01.01.91).
Code of Practice :
Working with Saffil Alumina Fibre.
American Conference of Governmental
Industrial Hygienists (ACGIH). Threshold Limit Values and Biological Exposure
Indices for 1990-91.
The contents of this note are given in good faith
but without warranty and the user must satisfy himself that the product is
entirely suitable for his purpose. Freedom from patent rights must not be
assumed.
SAFFIL LTD
Pilkington-Sullivan Site
Tanhouse Lane
Widnes
Cheshire
WA8 0US
United Kingdom
Tel: +44 (0)151 422
6700
Fax: +44 (0)151 422 6701