Kiken is a Chinese-style compound (i.e., a compound read with the on reading) meaning 'danger' or 'dangerous'.
In characters it is normally written , as in the following sign:
And yet, signs can also be found at railway stations where kiken is reduced to katakana (), as shown in the following example:
The rationale behind this use of katakana is possibly as follows:
Except for such station notices, the use of katakana to write the word kiken appears to be relatively uncommon. A Google search in August 2003 revealed the following pattern of usage on the Internet:
No reliable figures are available for kiken in hiragana () because this features as a fragment of many other Japanese words, not simply as a substitute for the characters . However, the number is unlikely to be large.