  We show how to extract from a sufficiently long time series of stationary
fluctuations of chemical reactions an estimate of the entropy production. This
method, which is based on recent work on fluctuation theorems, is direct,
non-invasive, does not require any knowledge about the underlying dynamics, and
is applicable even when only partial information is available. We apply it to
simple stochastic models of chemical reactions involving a finite number of
states, and for this case, we study how the estimate of dissipation is affected
by the degree of coarse-graining present in the input data.
