Past and future cadmium emissions from municipal solid-waste incinerators in Japan for the assessment of cadmium control policy.

Cadmium (Cd) is a harmful pollutant emitted from municipal solid-waste incinerators (MSWIs). Cd stack emissions from MSWIs have been estimated between 1970 and 2030 in Japan. The aims of this study are to quantify emitted Cd by category and to analyze Cd control policies to reduce emissions. Emissions were estimated using a dynamic substance flow analysis (SFA) that took into account representative waste treatment flows and historical changes in emission factors. This work revealed that the emissions peaked in 1973 (11.1t) and were ten times those in 2010 (1.2 t). Emission from MSWIs was two-thirds of that from non-ferrous smelting in 2010. The main Cd emission source was pigment use in the 1970s, but after 2000 it had shifted to nickel-cadmium (Ni-Cd) batteries. Future emissions were estimated for 2030. Compared to the business-as-usual scenario, an intensive collection of used Ni-Cd batteries and a ban on any future use of Ni-Cd batteries will reduce emissions by 0.09 and 0.3 1t, respectively, in 2030. This approach enables us to identify the major Cd emission source from MSWIs, and to prioritize the possible Cd control policies.

Historical perspectives on cadmium toxicology.

The first health effects of cadmium (Cd) were reported already in 1858. Respiratory and gastrointestinal symptoms occurred among persons using Cd-containing polishing agent. The first experimental toxicological studies are from 1919. Bone effects and proteinuria in humans were reported in the 1940's. After World War II, a bone disease with fractures and severe pain, the itai-itai disease, a form of Cd-induced renal osteomalacia, was identified in Japan. Subsequently, the toxicokinetics and toxicodynamics of Cd were described including its binding to the protein metallothionein. International warnings of health risks from Cd-pollution were issued in the 1970's. Reproductive and carcinogenic effects were studied at an early stage, but a quantitative assessment of these effects in humans is still subject to considerable uncertainty. The World Health Organization in its International Program on Chemical Safety, WHO/IPCS (1992) (Cadmium. Environmental Health Criteria Document 134, IPCS. WHO, Geneva, 1-280.) identified renal dysfunction as the critical effect and a crude quantitative evaluation was presented. In the 1990's and 2000 several epidemiological studies have reported adverse health effects, sometimes at low environmental exposures to Cd, in population groups in Japan, China, Europe and USA (reviewed in other contributions to the present volume). The early identification of an important role of metallothionein in cadmium toxicology formed the basis for recent studies using biomarkers of susceptibility to development of Cd-related renal dysfunction such as gene expression of metallothionein in peripheral lymphocytes and autoantibodies against metallothionein in blood plasma. Findings in these studies indicate that very low exposure levels to cadmium may give rise to renal dysfunction among sensitive subgroups of human populations such as persons with diabetes.

The trend and extent of heavy metal accumulation over last one hundred years in the Liaodong Bay, China.

An integrated analysis has been carried out on two cores dated by combination of (210)Pb and (137)Cs in order to characterize the extent of heavy metal accumulation in the Liaodong Bay, Northern China. The concentrations and burial fluxes of Zn, Pb, Cd, and Hg increased abruptly after late 1970s. The enrichment factors of Cd, Hg, Zn and Pb are more than 30, 10, 7, and 3.5, respectively, in the surface sediments. Coincident to the increase of heavy metal contents, the decreasing trend of (206)Pb/(207)Pb ratio indicated lead in the surface sediments mainly come from anthropogenic activities.

Bone cadmium and lead in prehistoric inhabitants and domestic animals from Gran Canaria.

Both lead and cadmium exposures derive from natural sources and also from industrialisation and certain habits, such as cigarette smoking in the case of cadmium. Some of these sources only affect human beings. The aim of this study was to determine the levels of lead and cadmium in bone samples of 16 prehispanic inhabitants of Gran Canaria, 24 prehispanic domestic animals (sheep, goat and pigs) from this island, 8 modern individuals, and 13 modern domestic animals. We found that modern individuals showed higher bone Cd values (mean=516.7+/-352.49 microg/kg, range=167.20-1125 microg/kg) than prehistoric ones (mean=85.13+/-128.96 microcg/kg, range=2.97-433 microg/kg). Values of prehistoric individuals did not differ from those of the prehistoric animals (mean=70.54+/-46.86 microg/kg, range=11.06-216.50 microg/kg), but were higher than those of the modern animals (mean=7.31+/-10.35 microg/kg, range=0-35.62 microg/kg). In the same way, modern individuals and modern animals showed approximately 7-fold higher bone Pb than ancient individuals and ancient animals, respectively. Ancient animals showed significantly lower Pb values than all the other groups, whereas modern animals showed Pb values comparable to those of the ancient individuals. A significant correlation was observed between bone Pb and Cd (r=0.61, P<0.001). Since bone cadmium accumulation leads to osteoporosis, we have also tested the relationship between histomorphometrically assessed trabecular bone mass and bone cadmium both in modern and ancient individuals. No significant relationship was found between these two parameters.

Trace metals in ancient hair from the Karluk Archaeological Site, Kodiak, Alaska.

Considerable interest exists in characterizing the extent of changes in methylmercury exposures from preindustrial to modern-day times. Hair is often preserved over centuries and has been useful in determining the extent of dietary trace metal exposures, particularly methylmercury. We examined 16 human hair samples taken from human hair bundles buried in the soil of the Karluk One Archaeological site located near the current Karluk village on the Kodiak Archipelago of Alaska. Hair samples were analyzed for total mercury, methylmercury, selenium, and cadmium. The mean total mercury level was 1.33 ppm (SD = 1.09). The mean methylmercury level, however, was considerably lower than the total mercury concentration: the mean methylmercury level was 0.03 ppm (SD = 0.02). The mean cadmium level was 0.15 ppm (SD = 0.14) and the mean selenium level was 5.22 ppm (SD = 5.73). While the concentration of total mercury in the Karluk hair samples is comparable to those observed in ancient hair from other locations, direct methylmercury quantization demonstrated that methylmercury levels were less than 2% of the total mercury in these hair samples. Because the hair was subjected to a variety of environmental influences over the centuries, the possibility of degradation of methylmercury in the hair over the last 400 to 800 years cannot be ruled out. The use of hair from remains found in more protected frozen or dry environments may provide the best evidence for the extent of preindustrial exposures to methylmercury and other trace metals.