Methyl Mercury Exposure at Niigata, Japan: Results of Neurological Examinations of 103 Adults

Table 2

Characteristics of subjects by hair mercury content.

	All
Mean age in years (1965) ± SD
Sex
Men	61 (59.2%)	11 (45.8%)	12 (50.0%)	12 (57.1%)	26 (76.5%)
Women	42 (40.8%)	13 (54.2%)	12 (50.0%)	9 (42.9%)	8 (23.5%)
Date symptoms began	1964–1973	1964–1973	1964–1970	1964–1972	1964–1971
Mean age in years (±SD) that symptoms began
Mean age in years of assessment of neurologic signs ± SD
Mean hair mercury content ± SD (μg/g)
Hair mercury content (μg/g) (min-max)	4.2–570.0	4.2–19.5	20.5–46.6	56.0–100.0	104.0–570.0
Analysis method of hair mercury (1965)
Dithizone	72 (69.9%)	10 (41.7%)	18 (75.0%)	13 (61.9%)	31 (91.2%)
Neutron activation	26 (25.2%)	13 (54.2%)	6 (25.0%)	5 (23.8%)	2 (5.9%)
Atomic absorption	5 (4.9%)	1 (4.1%)	0 (0%)	3 (14.3%)	1 (2.9%)

SD: standard deviation.