The risk can be mitigated by not using keywords (duh!). All keywords are listed in
keywords.h, located
somewhere within the filesystem.
The only all upper case keywords in my keywords.h are:
#define KEY_NULL 0
#define KEY___FILE__ 1
#define KEY___LINE__ 2
#define KEY___PACKAGE__ 3
#define KEY___DATA__ 4
#define KEY___END__ 5
#define KEY_AUTOLOAD 6
#define KEY_BEGIN 7
#define KEY_CORE 8
#define KEY_DESTROY 9
#define KEY_END 10
#define KEY_INIT 11
#define KEY_CHECK 12
IIRC, diotalevi has a module that dynamically lists all keywords for the installed perl.
Update: B::Keywords looks like the module...