The physical and chemical characteristics of particles in indoor air where high fluoride coal burning takes place.

In China, more than 10 million people suffer from fluorosis caused by the burning of high fluoride coal. Analysis of the particulate matters of indoor air from these fluorosis areas reveals a logarithmic distribution of particle sizes. The levels of F- and SO4(2-) adsorbed or absorbed on the particles ranged from 16.27 to 46.18 micrograms/m3 and from 244.7 to 374.6 micrograms/m3, respectively. Gaseous and soluble fluorides constituted a considerable proportion of the inorganic fluorides. Nevertheless, the level of F- in air was considered to be inadequate to cause the observed severity of fluorosis. It is speculated that additional intake of F- from contaminated foods might also be a major factor contributing to the fluorosis. Additionally, some volatile elements (e.g., sulfur and its derivatives) might have some relation to fluorosis of this type.

Cadmium exposure and health effects among residents in an irrigation area with ore dressing wastewater.

About 0.05 mg Cd l-1 was found in the irrigation water contaminated by the wastewater discharged from tungsten ore dressing plants, and about 1 mg Cd kg-1 was found in irrigated acid soils. The main sources of cadmium intake by residents of the polluted areas are agricultural products. The average intake of cadmium was 367-382 micrograms day-1, and for smokers 417 micrograms day-1. Among the residents who have been exposed to cadmium for more than 25 years, cadmium absorption (urinary cadmium greater than or equal to 10 micrograms g-1 creatine) was 60% and an early effect on the target organ (urinary cadmium greater than or equal to 15 micrograms g-1 creatinine and urinary beta 2-microglobulin greater than 500 micrograms g-1 creatinine) was detected in 17% of the sample of 433 persons. Levels of urinary cadmium and blood cadmium exceeded the critical value in the exposed group. The concentrations of urinary calcium, beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase were significantly higher in residents of contaminated areas than in those of control areas. Case-control study of the residents shows that many have suffered from a nephropathy with tubulo-interstitial abnormalities. Owing to the combined cadmium effect, the cases with fractional beta 2-microglobulin excretion greater than 0.10 were 46% in the exposed population, and were much higher than that in the control group (20.3%).

Assessment of lead contamination of the general environment through blood lead levels.

More than 2000 blood samples were collected at random from full-time middle school teachers in 9 cities of China and analyzed for lead concentration with strict quality assurance procedures. Questionnaries about the smoking habits, alcohol consumption, residence condition, and fuel used at home were filled out by each person, and information about traffic, and lead concentration in different areas of the environment was also collected as far as possible. The result showed that the geometric mean of blood lead levels of teachers in different cities was ranging between 59-82 µg l(-1) among them the lowest levels were found in Nanjing and the highest in Shanghai. The difference between the lowest and the highest value was only 23 µg l(-1). Comparing with the results of WHO/UNEP and CEC projects. The overall geometric average blood level in China is lower than in all the other countries except Japan. It indicates that the lead pollution in the general environment of China was not as severe as in the participating countries of WHO/UNEP and CEC projects. This may be attributed by the following factors: The less automobile triffic, the larger proportion of non-leaded gasoline used and the less canned food consumption. Factors influencing the lead levels in blood were also analyzed and the 'normal value' (95% upper limit) of blood lead was assessed to be 160 µg l(-1).