The Synergism of Mercury and Various Other Substances
In a study (Wataha et al) which looked at a common amalgam (Dispersalloy), the researchers reported.... "Dispersalloy was severely cytotoxic initially when Zn release was greatest, but was less toxic between 48 and 72 hours as Zn release decreased." Zn, at the amount released from an amalgam, should not reach cytotoxic levels. It does however, potentiate the toxicity of the mercury released by tying up protective mercury chelators due to the fact that Zn and Hg both have a high affinity for sulfhydryls. In experiments investigating this effect, it was found that addition of non-toxic amounts of Zn2+ (5-10 micromolar) enhanced the toxicity of mercury about 5-fold. (Personal communication: Prof. Boyd Haley. Prof. and Chair, Dept of Chemistry, Univ of Kentucky)
The effects of mercury and lead combined have also been reported. One study showed that when a lethal dose (LD1) of mercury was combined with 1/20 LD1 of lead, the combination of the two resulted in a LD100 in the test animals (Schubert). This has not been investigated in human subjects but it is clearly reasonable to assume the possibility of similar effects in amalgam-bearing humans.
Wataha et al., Dental Materials 10(5):pp298-303 1994 )
Schubert J. Combined effects in toxicology-a rapid systematic testing procedure cadmium, mercury and lead.
J. Toxic Environ Health 1978;4 763-776 )