Guidelines for Metals and Metalloids in Ambient ... - ARCHIVE: Defra

Beryllium
respirable particulate beryllium substantially increases the risk of developing
sensitisation and CBD.
220. The USA Occupational Safety and Health Administration (OSHA) currently
list a Permissible Exposure Limit (PEL) of 2 µg/m 3 as an eight-hour timeweighted
average (TWA) for beryllium and its compounds. This is
accompanied by an acceptable ceiling concentration of 5 µg/m 3 . Exposures are
allowed to exceed 5 µg/m 3 (but never exceed 25 µg/m 3 ) for a maximum of 30
minutes during an 8-hr shift but there must be corresponding periods of lower
exposure such that exposure for the 8-hr shift does not exceed the 8-hr TWA
PEL. OSHA is in the process of re-evaluating these limits owing to concerns
that they may not be adequate to protect health (OSHA, 2005).
221. In the UK the maximum exposure limit (MEL) assigned for beryllium and its
compounds is 2 µg/m 3 , averaged over an 8-hour period (HSE, 1995). Maximum
Exposure Limits are occupational exposure limits set under the Control of
Substances Hazardous to Health (COSHH) Regulations (2002 as amended).
4.4.2 Lung cancer
222. The USEPA (1998) has estimated the unit health risk from lung cancer due to
continuous exposure to beryllium to be 2.4 x 10 -3 per µg/m 3 . On this basis they
have further estimated that an individual inhaling in an atmosphere
containing 0.4 ng/m 3 beryllium throughout life, would theoretically have no
more than a one in a million increased chance of lung cancer; while an
individual spending a lifetime inhaling an atmosphere containing 4 ng/m 3
beryllium, would not have more than a one in a hundred thousand increased
chance of developing lung cancer.
223. Using the EPA figures Willis and Florig (2002) suggest that for an individual
exposed to 2 µg/m 3 of beryllium for a 2,000-hour work year and a 40-year
working life, the lifetime lung cancer risk would be 0.0005, which is an order
of magnitude smaller than that of CBD for sensitised individuals. These
authors further suggest that the lifetime lung cancer mortality rate for an
individual living in close proximity to a beryllium-emitting industrial site,
which is in compliance with the EPA limit for concentrations around
beryllium plants (0.01 µg/m 3 ) will be approximately 2 x 10 -5 . McCanlies et al.
(2003) also suggest that the risk of CBD in sensitised individuals vastly
exceeds that of lung cancer.
4.5. Justification for air quality guideline
224. Because the risks of sensitisation and CBD are apparent at far lower
exposures, it seems appropriate to base a guideline on these rather than on the
risk of lung cancer.
225. Use of a no observed adverse effects level (NOAEL) of 0.02 ug/m 3 for both
sensitisation and CBD (Kelleher et al., 2001) with division by ten to allow for
the greater exposure duration of the general public and a further ten to allow
for the presence of susceptible individuals would produce a guideline value of
0.2 ng/m 3 .
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