Low Cadmium Levels in Urine of Residents in two Prefectures where Cadmium Levels in Locally Harvested Brown Rice are Higher than in other Prefectures in Japan

Abstract

Recent publications in Japan suggest that Cd in river beds and locally harvested rice tend to be higher in seven prefectures in the north-eastern part on the coast of the Sea of Japan (the high-Cd zone). The present study was initiated to investigate the current level of exposure to Cd and possible health effects among local populations in the zone. Thus, levels of Cd and three tubular dysfunction markers [i.e., α(1)-MG, β(2)-MG, and N-acetyl-β-D-glucosaminidase (NAG)] were examined in urine of local residents (700 and 704 adult women, respectively) in two prefectures (prefecture 1 and prefecture 7), which were located in the north-east (prefecture 1) and south-west ends (prefecture 7) of the high-Cd zone. Urinary Cd levels [e.g., 0.99 and 0.78 μg/l as geometric mean (GM) for observed (non-corrected) values, respectively] in prefecture 1 and prefecture 7 were comparable to the levels in other parts of Japan (All Japan-A; 0.99 μg/l). Correspondingly, GM values for α(1)-MG (2.29 and 1.99 mg/l vs. 2.17 mg/l for All Japan-A) and for β(2)-MG (87 and 80 μg/l vs. 99 μg/l for All Japan-A) were not elevated, and NAG also stayed unchanged (2.89 and 2.87 units/l for prefecture 1 and prefecture 7, respectively). Evaluation in combination with the findings in other five prefectures in the zone suggests that Cd exposure is equal to the national average both in prefecture 1 and in prefecture 7, whereas Cd exposure appeared to be elevated in the central part of the zone. The observation appears to be on line with geographical location of the two prefectures that they are on the two ends of the zone of high natural Cd background.

Cadmium Exposure in General Populations in Japan: a Review

“…3 [C] and [D]) and well within corresponding GSD ranges. The findings that the elevation in Cd-U cr (as an internal exposure marker) varied in parallel with Cd-BrR (as an external Cd exposure marker) suggest that the exposure was there, but no clear-cut indication was available to suggest an increased prevalence of tubular dysfunction among the local general populations 42) . …”

“…No. 15 was surveyed in the former survey, and the data were evaluated also in combination with the 6 prefectures because of its sea-coast location (Revised from Ezaki et al 13) ; Yamagami et al 40) , Moriguchi et al 41) and Ikeda et al 42) ). subjected to regression analysis to examine if Cd-D could be estimated from Cd-B or Cd-U cr .…”

“…Following the information, a supplemental survey was initiated in 2004-2009 in the 6 prefectures (for locations, see prefectures with solid circles in Fig. 1 [B]) involving 50-1000 women/prefecture who offered spot urine samples (some offered blood samples in addition) [40][41][42] .…”

Bi-linear dose–response relationship in general populations with low-level cadmium exposures in non-polluted areas in Japan

“…Data on age, urine speciWc gravity, and urinary concentrations of creatinine (CR or cr), cadmium (Cd), 1 -microglobulin ( 1 -MG), 2 -microglobulin ( 2 -MG), N-acetyl--D-glucosaminidase (NAG) as well as urine speciWc gravity (SG) were cited from previous publications of Ezaki et al (2003) and Tsukahara et al (2003) on ten prefectures, Moriguchi et al (2005aMoriguchi et al ( , b, 2010 on three prefectures, Yamagami et al (2006) on one prefecture, and Ikeda et al (2010) on two prefectures. The basic parameters for the cited cases in combination are summarized in Table 1 (the total group).…”