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Health and Safety Aspects
Advice
to Users
Extensive tests have been conducted
on Saffil alumina fibre and all results lead to the conclusion that
Saffil fibre is unlikely to have any significant toxic 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 is designed and produced 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
1 Control of Substances Hazardous to
Health (Amendment) Regulations 1990. (Effective 01.01.91).
2 Code of Practice : Working with Saffil Alumina Fibre.
3 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 0RY
United Kingdom
Tel: +44 (0)151 422 6700
Fax: +44 (0)151 422 6701
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