Proceedings of the International Cyanide Detection Testing Workshop

Validation Methods for the Determination of Cyanide and
Cyanide Metabolites in Coral Reef Fishes
Robert Kobelski
National Center for Environmental Health
Centers for Disease Control and Prevention
rmk9@cdc.gov
The consensus of the Working Group was that there exist serious gaps in the understanding of
the metabolism and elimination of the cyanide anion and its major metabolites in fi sh. Without a
better understanding of these processes the implementation of an exposure assessment method
that would meet legal requirements would be diffi cult. The recommendation of the Working
Group is that a research program be designed to generate the data necessary to determine the
determine the availability of cyanide and its metabolites for exposure assessment versus the
time involved with the local collection of fi sh, their transport to a fi xed site laboratory prior
to export and their arrival at the import destination prior to the implementation of an analysis
method at any point in the delivery chain.
Background
In a number of locations both ornamental and live food fi sh are captured using techniques
such as stunning with an aqueous solution containing the cyanide anion (CN - ). This technique
is destructive to the reef, the individual fi sh and the sustainability of the population and is
illegal in Indonesia, the Philippines and Vietnam. To determine if fi sh are captured using this
destructive technique there must be a forensically supportable analysis for cyanide exposure in
reef fi sh implemented in a timely fashion after capture of the fi sh.
The length of time between capture and delivery of the fi sh to a capable laboratory can range
from fi ve to fourteen days. For a laboratory analysis to be viable the analyte must be stable and
at elevated levels in the sample long enough for the sample to be delivered to the laboratory
and for the analysis to be conducted. Data from mammals suggests that the cyanide anion is
readily metabolized to thiocyanante (SCN - ) and 2-aminothiazoline-4-carboxylic acid (ATCA),
with a half-life of approximately one hour. If metabolism in fi sh is similar there would not
be an elevated level of cyanide in a fi sh when it reached the laboratory site For there to be an
elevated level of cyanide after fi ve days the half-life would have to be approximately 10 hours,
but this toxicokinetics parameter has not been determined.
To determine what analyte can be targeted for forensic analysis the following research needs
to be conducted:
1) the half-life of cyanide in fi sh has to be determined and the variation in half-life with
respect to different species must be defi ned,
2) the half-life of thiocyanate, the major metabolite of cyanide, in fi sh must be determined
as well as the specie-to-specie variation in half-life
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