C.-S. Moon

Urban population exposure to lead and cadmium in east and south-east Asia

Information is still scarce for many Asian countries on general population exposure to two potentially toxic heavy metals of lead (Pb) and cadmium (Cd). The present review on publications from this study group is intended to provide an overview of the non-occupational exposure to Pb and Cd among general populations in east and south-east Asia. During the period of 1991-1998, surveys were conducted in four cities in south-east Asia, five cities in mainland China, and two cities each in Japan and Korea. Peripheral blood, morning spot urine and 24-h food duplicate samples were collected from 20-50 non-smoking adult women in each survey site. The samples were digested by heating in the presence of mineral acids, and then analyzed by inductively-coupled plasma mass spectrometry for the metals in blood (Pb-B and Cd-B), in urine (Pb-U and Cd-U), and in food duplicate (Pb-F and Cd-F). Measures were subjected to statistical analysis with an assumption of log-normal distribution. Pb-B, Pb-U and Pb-F levels varied substantially among the 11 urban sites; GM distributed in ranges of 32-65 microg/l for Pb-B, 2.1-7.5 microg/g cr (creatinine) for Pb-U, and 7-32 microg/day for Pb-F. The same was also the case for Cd exposure parameters, the distribution ranges being 0.5-1.8 microg/l for Cd-B, 1.2-3.1 microg/g cr for Cd-U, and 5-32 microg/day for Cd-F. It appeared that the exposure to Pb and Cd was highest in Kuala Lumpur, and Tokyo + Kyoto, respectively, and lowest in Tokyo + Kyoto and in Manila. Additional surveys in Japan showed that Pb exposure was even lower in rural areas than in Tokyo + Kyoto. When compared with the values reported in the literature, Pb exposure levels among Asian populations appear to be similar to the levels in Europe and in the United States, whereas Cd exposure seems to be higher in Asia than in Europe. The contribution of the dietary route in Pb absorption was variable and was inversely related to the extent of air pollution, whereas Cd uptake was almost exclusively via the dietary route with little contribution of the respiratory route.

Cadmium exposure of women in general populations in Japan during 1991–1997 compared with 1977–1981

Objectives: The Japanese people are known to have high environmental exposure to cadmium (Cd). The present survey was initiated to elucidate possible changes in the intensity of Cd exposure to the population by comparison of the present exposure level with the situation some 15 years ago. Methods: During 1991–1997, 24-h food-duplicate samples, peripheral blood specimens and morning spot urine samples were collected from 588 non smoking women from 27 survey sites in six regions, where food-duplicate and blood samples had also been obtained during 1977–1981 from 399 women. The samples were wet-ashed (after homogenization in the case of food-duplicates), and Cd in the wet-ashed samples was analyzed by inductively-coupled plasma mass spectrometry for Cd intake via foods (Cd-F), Cd concentration in blood (Cd-B) and Cd concentration in urine (Cd-U). The Cd-F and Cd-B were compared with the Cd-F and Cd-B obtained at the same sites in the 1977–1981 survey. Results: The exposure levels during 1991–1997 were such that Cd-F, Cd-B and Cd-Ucr (Cd–U after correction for creatinine concentration) were 25.5 μg/day, 1.90 μg/l and 4.39 μg/g creatinine. Comparison with the 1977–1981 survey results (i.e., 37.5 μg/day for Cd-F and 3.47 μg/l for Cd-B) showed that there were significant reductions (by 32 and 45%) in both parameters respectively during the last 15 years. The dietary route was an almost exclusive (i.e., 99% of the sum of dietary and respiratory uptake) route of Cd uptake, of which Cd in rice (11.7 μg/day) contributed about 40% of the total dietary intake. When compared among survey sites, inter-site variation in dietary Cd intake was primarily due to differences in the intake through boiled rice. Despite the recent reduction in Cd exposure, the current exposure level for Japanese people is still higher than the levels among other rice-dependent populations in Asia as well as in other parts of the world. Comparison was made between the present findings in general populations and observations among known Cd-pollution cases in Japan. Conclusions: Dietary uptake is an almost exclusive route of Cd exposure in the general Japanese population. Boiled rice is a strong determinant of variation in dietary Cd intake. Whereas there was a substantial reduction in Cd exposure among Japanese populations in the last 15 years, the current level is still high when compared internationally.

Possible effects of environmental cadmium exposure on kidney function in the Japanese general population.

Objectives: To examine whether the current level of environmental exposure to cadmium (Cd) is associated with kidney dysfunction among general populations in Japan. Methods: A nationwide survey was conducted in Japan from 1991 to 1997 at 30 survey sites (with no known environmental heavy metal pollution), by the collection of 24-h food-duplicate samples, peripheral blood specimens and morning spot urine samples. In practice, 607 non-smoking adult women provided these samples. After being wet-ashed, the samples were analyzed for Cd in food duplicates (Cd-F), in blood (Cd-B) and urine (Cd-U) by inductively-coupled plasma mass spectrometry (ICP-MS). Urine samples were also analyzed for α1-microglobulin (α1-MG), β2-microglobulin (β2-MG) and retinol-binding protein (RBP), creatinine (cr) and specific gravity. Possible tubular dysfunction in association with Cd exposure was examined by simple, multiple and logistic regression analyses, and comparison among three different Cd-dose groups. To minimize the confounding effects of aging, 367 women from 41 to 60 years old were selected and subjected to the same statistical analyses. Results: The analysis of a whole population of 607 women showed that α1-MG and possibly β2-MG increased as a function of Cd-F, Cd-B and Cd-U. When the analysis was repeated with the selected population of 367 women aged 41–60, the Cd dose-dependent changes in α1-MG and β2-MG became less evident. The distribution of the selected population with α1-MG above two low cut-off values of >4.9 and >8.4 mg/g cr or with β2-MG above the lowest cut-off value of >400 μg/g cr, was biased toward the group with higher Cd-Ucr, but such bias was not significant for both α1-MG and β2-MG when higher cut-off values were employed. No bias was detected with RBP. Logistic regression analysis with α1-MG, β2-MG and RBP (with cut-off values given above) in combination with age, Cd-F, Cd-B and Cd-Ucr gave essentially the same results. Conclusions: The evidence for kidney dysfunction was of borderline significance in the present study population for which geometric mean Cd-F, Cd-B and Cd-U were 24.7 μg/day, 1.76 μg/l, and 3.94 μg/g cr, respectively. The findings might suggest at the same time that the safety margin is small for the Japanese general population regarding environmental Cd exposure.

Exposure of women in general populations to lead via food and air in East and Southeast Asia

BACKGROUND Despite increasing public concern of the possible health effects of lead (Pb) on general populations, reports on Pb levels in blood (Pb-B) and urine (Pb-B), as well as Pb intake via foods (Pb-F) for many Asian countries are scarce. The present study was initiated to elucidate the extent of non-occupational Pb exposure among general populations in East and Southeast Asia. METHODS In 1991-1997, peripheral blood, morning spot urine and 24-hour food duplicate samples were collected from 20 to 50 non-smoking adult women in each of four cities in Southeast Asia and five cities in Mainland China, and two cities each in Japan and Korea. The samples were wet-ashed and then analyzed by inductively coupled plasma mass spectrometry for Pb-B, Pb-U and Pb-F. Measures after logarithmic conversion were subjected to ANOVA and regression analysis. RESULTS Geometric mean values in cities in East and Southeast Asia were in ranges of 32-65 microg/L for Pb-B, 2.1-7.5 microg/g cr for Pb-Ucr, and 7-32 microg/day for Pb-F. The values for a combination of two cities of Tokyo and Kyoto, Japan (38 microg/L for Pb-B and 9.3 microg/day for Pb-F) appeared to be lower than the values for other Asian cities, and the values for all Japan (thus including both urban and rural areas) were even lower (19 microg/L for Pb-B and 7.7 microg/day for Pb-F). Comparison of Pb uptake via respiratory and dietary routes showed that Pb via dietary route accounted for 15% of the total in Manila where Pb in air was high (ca. 650 ng/m(3)), whereas it was 54% in Tokyo+Kyoto where Pb in air was low (ca. 75 ng/m(3)). CONCLUSIONS When compared internationally, Pb-F and Pb-B in Asia in general are similar to or somewhat higher than the levels in Europe and USA, whereas the levels in Japan are probably lower than the two latter areas. In Asia, Pb-F accounted for 15-54% of all Pb sources, the percentage being variable depending on local conditions especially Pb in atmospheric air.

Evaluation of urinary cadmium and lead as markers of background exposure of middle-aged women in Korea: dietary intake as an influential factor.

The study was conducted to examine the validity of urinary cadmium (Cd) and lead (Pb) in comparison with the metals in blood as a biological marker of non-occupational exposure of general populations. Participants in four survey sites in Korea (107 non-smoking Korean women aged 30-49 years) offered peripheral blood, morning spot urine, and 24-h total food duplicate samples. Analysis of Cd and Pb was accomplished by graphite furnace atomic absorption spectrophotometry. The analyse levels were evaluated on an individual basis (n = 107) and also on a survey site basis, i.e. in terms of geometric means for the groups in the survey sites (n = 4). Cd in urine (as observed, or after correction for creatinine concentration or a specific gravity) correlated with Cd in blood on an individual as well as survey site basis, and tended to correlate with Cd in food duplicates on the survey site basis. Correlation of Pb in urine with Pb in blood was weaker than that of Cd in urine with Cd in blood both on the individual and survey site basis. Pb in urine correlated with Pb in food duplicates either weakly or even negatively when examined on a survey site basis. It was concluded that Cd in urine can be most probably employed as a biological marker of environmental Cd exposure of general population, whereas less support was obtained for Pb in urine as an exposure marker.

Background exposure of general women populations in Japan to cadmium in the environment and possible health effects

1. The surveys were conducted in 1990s on 470 non-smoking adult women [with no specific exposure to cadmium (Cd)] in 22 sites in six regions in Japan. 2. It was found that the dietary Cd intake (as a grand geometric mean) was 25.9 microg/day, the Cd level in blood was 2.1 microg/l, and Cd level in urine was 2.1 microg/g creat. 3. Cd in rice contributed about 30% of total dietary Cd intake. 4. There was a substantial reduction in Cd burden when compared with observation in 1980s. 5. Effects on kidney functions were essentially negative when evaluated in terms of beta2-microglobulin (beta2-MG), but might be positive when alpha1-microglobulin (alpha1-MG) was evaluated; further studies are apparently necessary. 6. No effects on liver functions were detected.

Correlation between concentration in urine and in blood of cadmium and lead among women in Asia

The objectives of the present study are to examine if there exists a quantitative relationship between lead in urine (Pb-U) and that in blood (Pb-B), and also between cadmium in urine (Cd-U) and that in blood (Cd-B) among the general populations who are environmentally (and not occupationally) exposed to these elements at various levels. For this purpose, peripheral blood and morning spot urine samples were collected in 1991-1998 from approximately 50 non-smoking adult women each in four cities in south-east Asia and five cities in mainland China, and two cities each in Japan and Korea. The samples were wet-ashed and then analyzed by inductively-coupled plasma mass spectrometry for Pb-B, Cd-B, Pb-U and Cd-U. Measured values were subjected to analysis to detect possible correlation between the pairs of parameters. A significant correlation between Pb-B and Pb-U was observed when the intensity of Pb exposure (as expressed by Pb-B) was relatively high so that the correlation was significant in all cases studied when Pb-B level was, e.g. 50 microg/l or above. It was also observed that the correlation between Cd-B and Cd-U was significant when Cd-B was, e.g. > 1 microg/l. Thus, it is possible to deduce that, in environmental health, Pb-B and Cd-U levels can be estimated on a group basis from Pb-U and Cd-B, respectively, when Pb and Cd exposure levels are relatively high, e.g. with Pb-B and Cd-B of > 50 microg/l and > 1 microg/l.

Exposure of citizens in China and in Japan to lead and cadmium : a comparative study

To compare the background exposure of general urban populations to lead (Pb) and cadmium (Cd) in China and Japan, 250 adult women in five Chinese cities and 72 women in three Japanese cities were surveyed by means of collection and analyses of food duplicate and blood samples. The results show that the geometric mean dietary Pb intake and Pb level in blood were significantly higher among Chinese (24.6 microg/day and 45.8 ng/ml) than their counterparts in Japan (14.6 microg/day and 32.2 ng/ml). In contrast, Cd exposures were significantly higher among Japanese women (34.1 microg/day and 1.91 ng/ml) than among Chinese women (8.8 microg/day and 0.61 ng/ml). Thus, the public health concern should be focussed on Pb exposure for Chinese population and Cd for Japanese people.

Comparison of urinary bromide levels among people in East Asia, and the effects of dietary intakes of cereals and marine products

Groups of people with no occupational exposure to Br-containing chemicals (29-54 year old, mostly women) in Japan, China and Korea, respectively, offered spot urine samples. Those in China and Korea offered 24 h duplicates of foods of the day. Urine samples were analyzed for Br by ECD-gas chromatography (ECD-GC) after derivatization to methyl bromide, and the Br-U was adjusted for a specific gravity of 1.016. Food intake data were based on national statistics and supplemented by the food duplicate data. Mean Br-U was 5.4 and 6.5 mg/l for Japanese men and women, respectively. Mean levels were in a range of 1.8-2.8 mg/l for four groups of Chinese, and 8-12 mg/l for the four groups of women in Korea. Br-U levels among Korean women were close levels reported for occupational exposure to 1- or 2-bromopropane, or methyl bromide. Regression analyses showed that Br-U levels were influenced by the intake of marine products (such as sea algae, sea fish and shellfish) and fruits, and inversely relate to intakes of cereals and potato.

Normal liver function in women in the general Japanese population subjected to environmental exposure to cadmium at various levels

Objectives: Whereas it is well established that environmental exposure to cadmium (Cd) may induce kidney dysfunction, less attention has been paid to the possible disturbance of liver function by Cd exposure. The possibility that liver function is adversely affected by current levels of environmental exposure to Cd as investigated in women in the general population in Japan, where the background level of exposure to Cd is known to be high. Methods: From 1991 to 1997, 24-h food duplicate, peripheral blood and morning spot urine samples were collected from 607 non-smoking and non-habitually drinking women (age range 19–78 years) at 30 survey sites (with no known environmental pollution from heavy metals) throughout Japan. Liver function parameters in serum were examined by conventional methods. After wet-ashing, the food duplicate, blood and urine samples were analyzed for Cd intake via food (Cd-F), Cd in blood (Cd-B), and Cd in urine (Cd-U) by inductively-coupled plasma mass spectrometry. Results: The geometric mean values for Cd-F, Cd-B, and Cd-U were 24.7 (27.1) μg/day, 1.76 (2.07) μg/l, and 3.94 (4.61) μg/g creatinine (values in parentheses for 41- to 60 year-old women), respectively. It as found that the three parameters of ALP, ALT, and AST activity were positively and significantly related to the age of the subjects (whereas no association as detected in cases of γ-GTP, LAP, and albumin). Accordingly, a further analysis as made with 367 women selected by age (41–60 years; about 60% of the total population). Essentially, no Cd dose-dependent changes in liver function parameters were observed in the selected population of this narrower age range. Conclusions: Overall, it seemed prudent to conclude that liver function as not disturbed by the current environmental exposure to Cd in Japan.