Strategy For Limiting Risks Human Health Draft of ... - ECHA - Europa

Repeated dose toxicity
Local effects
Inhalation exposure
For prolonged inhalation exposure of workers to cryolite, data on possible health effects are
available from different sources such as mining and processing of natural cryolite, production
of syntethic cryolite and manufacturing of aluminium. There has been no indication for
cryolite specific chronic respiratory effects in humans although specific examinations have
been made (x-ray photography, pulmonary function tests, questionaires concerning incidences
of acute pulmonary symptoms). Exposure in some cases has been rather high and longlasting,
causing severe skeletal fluorosis.
In a well-conducted 90-day inhalation study rats were exposed snout-only to particulate
aerosols of cryolite in the concentration of 0, 0.21, 1.04, and 4.6 mg/m 3 . Alveolitis with
interstitial thickening of alveolar duct walls and increased collagen in alveolar ducts occurred
in the high dose group. At the intermediate dose of Cryolite, a proportion of rats had
interstitial thickening of the alveolar duct walls. These effects might indicate of the start of a
fibrotic process in the lung. At the low dose (0.21 mg/m 3 ) no effect was observed.
For the risk assessment this NOAEC of 0.21 mg/m 3 is used as starting point concerning
effects of cryolite after repeated inhalation.
For the identification of the reference MOS the following aspects are taken into account: The
human data give no indication for cryolite specific chronic respiratory effects. Therefore, the
NOAEC gives a very precautious value for the evaluation of this endpoint. On that
background it does not seem indicated to apply any additional assessment factors like inter- or
intraspecies extrapolation or duration adjustment. On the other hand the NOAEC, based on a
90-day study, might make a duration factor of about 2 necessary, because a progression of
effects in the lungs (thickening of alveolar ducts and increased collagen) cannot excluded. In
summary for the reference MOS a value of about 2 is proposed; the critical exposure level
calculates then to 0.1 mg/m 3 (0.2 mg/m 3 / 2).
Table 2.2 shows, that all scenarios exceed the critical exposure level thus giving reason for
concern.
17
Conclusion: iii