Several studies have been conducted in recent years to investigate what role, if any, static magnetic fields may play in health and healing. Unbiased studies of magnetic therapy are problematic, since magnetisation can be easily detected, for instance, by the attraction forces on ferrous (iron-containing) objects; because of this, effective blinding of studies (where neither patients nor assessors know who is receiving treatment versus placebo) is difficult.[13] Incomplete or insufficient blinding tends to exaggerate treatment effects, particularly where any such effects are small.[14] Health claims regarding longevity and cancer treatment are implausible and unsupported by any research.[8][15] More mundane health claims, most commonly about anecdotal pain relief, also lack any credible proposed mechanism and clinical research is not promising.[7][16][17]