  Recent papers by Busza et al. (BJSW) and Dar et al. (DDH) argue that
astrophysical data can be used to establish small bounds on the risk of a
"killer strangelet" catastrophe scenario in the RHIC and ALICE collider
experiments. DDH and other commentators (initially including BJSW) suggested
that these empirical bounds alone do give sufficient reassurance. This seems
unsupportable when the bounds are expressed in terms of expected cost -- a good
measure, according to standard risk analysis arguments. For example, DDH's main
bound, $p_{\rm catastrophe} < 2 \times 10^{-8}$, implies only that the
expectation value of the number of deaths is bounded by 120. This paper
reappraises the DDH and BJSW risk bounds by comparing risk policy in other
areas. For example, it is noted that, even if highly risk tolerant assumptions
are made and no value is placed on the lives of future generations, a
catastrophe risk no higher than $\approx 10^{-15}$ per year would be required
for consistency with established policy for radiation hazard risk minimization.
It is concluded that the costs of small risks of catastrophe have been
significantly underestimated by BJSW (initially), by DDH and by other
commentators. Lessons for future policy are proposed.
