In a new article, authors Janet Rothwell and Paul Boyd, of the University of Manchester, UK, show amalgam effects in an area that has not previously gained much attention:

Rothwell, Janet A. and Boyd, Paul J.(2008) 'Amalgam dental fillings and hearing loss',  International Journal of
Audiology,47:12,770 - 776

Abstract
In this study we investigated the effects of amalgam
dental fillings on auditory thresholds. Participants (n
39) were non-smoking women age 40 to 45. Regression
and correlation analyses were performed between auditory
thresholds, measured from 0.25 to 16 kHz, and the
number/surface area of dental fillings, using the ASHA
criteria for ototoxic change as a reference for comparison.
No significant correlation (p
0.05) was found between
composite (non-amalgam) filling or drilling data and
auditory thresholds. However, there was a significant
positive linear correlation between amalgam filling data
and auditory thresholds at 8, 11.2, 12.5, 14, and 16 kHz.
The strongest association (r0.587, n39, pB.001, r2
0.345) was at 14 kHz, where each additional amalgam
filling was associated with a 2.4 dB decline in hearing
threshold (95% confidence interval [CI], 1.3
3.5 dB). The
results suggest an association between more amalgam
fillings and poorer thresholds at higher frequencies, which
could contribute to presbyacusis in developed countries.
This provides further argument for the use of amalgams
to be phased out where suitable alternatives exist.