ଛାଞ୍ଚ:R50
The chemical-risk Template:R50 generates the redirection title "R50: Very toxic to aquatic organisms" (as the link text for "R50"), which links to article "List of R-phrases" as the description page for all those R-codes. There are dozens of similar R-phrase templates.
Also see: {{Rlink|rcode}} - template to link any rcode.