Diffuse alopecia related to ingestion of toxic metals from the environment has been observed in 36 patients. Copper, arsenic, mercury and cadmium were involved and the intensity of the hair cycle, heralded by presence of dystrophic hairs, was proportional to the toxic amount detected in blood and urine.
Pirard GE. Toxic Effects of Metals from the Environment on Hair Growth and Structure. J Cutaneous Pathology. Vol 6, Issue 4, pp237-242, 1979
http://www.ncbi.nlm.nih.gov/pubmed/227944