Threshold levels of urinary cadmium in relation to increases in urinary beta2-microglobulin among general Japanese populations.
Through literature survey, paired data on cadmium (Cd) and beta(2)-microglobulin (beta(2)-MG) levels (as corrected for creatinine concentration) in urine (i.e., Cd-Ucr and beta(2)-MG-Ucr) among Japanese populations were available for 32 groups of men and 58 groups of women in 12 publications. Plotting of the Cd-Ucr and beta(2)-MG-Ucr data for the groups of women showed that beta(2)-MG-Ucr stayed unchanged when Cd-Ucr was at lower levels, whereas beta(2)-MG-Ucr increased sharply when Cd-Ucr was in excess of 10-20 microg/g cr. Regression analysis was made for groups of women with no elevation in beta(2)-MG-Ucr, and those with >400 or >1000 microg beta(2)-MG-U/g cr. A threshold Cd-Ucr level in relation to an increase in beta(2)-MG-Ucr was estimated as Cd-Ucr at the point of intercept of the two regression lines, one with no beta(2)-MG-Ucr elevation, and the other with >400 or >1000 microg beta(2)-MG-U/g cr. Cd-Ucr at the point of flexion thus calculated was 11-12 microg/g cr. Such observation was quantitatively reproduced by the analysis of data for men, giving 10-11 microg Cd-U/g cr at the point of flexion. This study suggests that the relationship of beta(2)-MG-Ucr with Cd-Ucr is not linear but in the shape of letter 'J', i.e., beta(2)-MG-Ucr increases sharply when Cd-Ucr is in excess of 10-12 microg/g cr.
Ikeda
M
M
Kyoto Industrial Health Association, 67 Nishinokyo-Kitatsuboicho, Nakagyo-ku, Japan. ikeda@kyotokojohokenkai.or.jp
Ezaki
T
T
Tsukahara
T
T
Moriguchi
J
J
Furuki
K
K
Fukui
Y
Y
Ukai
H
H
Okamoto
S
S
Sakurai
H
H
D000328:Adult; D002104:Cadmium / Q000652:urine*; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D011153:Population; D012044:Regression Analysis; D012737:Sex Factors; D001613:beta 2-Microglobulin / Q000652:urine*
D001613:beta 2-Microglobulin; D002104:Cadmium