HEALTH IMPACTS OF RESIDENTIAL COAL USE IN CHINA

Introduction

Arsenic poisoning (arsenism) caused by domestic combustion of mineralized coal affects about 10,000 people in southwest China. Fluorine poisoning (fluorosis) may affect as many as 10 million people in the same region.

Figure 1. The areas of endemic arsenism are in southwest Guizhou Province. The red dots mark the locations of "carlin-type" sedimentary rock-hosted gold deposits. The emplacement of the gold and arsenic were likely deposited by the same mineralizing fluids.

Figure 2. Much of Guizhou Province is underlain by Permian and older limestones on which have developed classic karst topography. The topographic elevations are generally between 2,000 and 3,000 meters. It is chilly and damp in the fall and winter. The health problems in the region are a consequence of the complex interaction of geology, topography, climate, and cultural factors including housing style, food preferences, energy needs, and economic conditions.

Figure 3. A small village in Guizhou Province, China. Note that none of the houses have chimneys, even though all of them contain coal-burning stoves.

Figure 4. Typical small coal mining operation in Guizhou Province, China. As men mine the coal, women load the trucks. By the early 1900s the forests had been essentially denuded and the people turned to the abundant coal resources for their primary energy needs. Unfortunately, some of the coals had experienced mineralization which cause them to be deleterious to human health when improperly combusted.

Figure 5. Even in major cities such as Guiyong, coal is used as the primary fuel for heating shops.

Figure 6. View of a typical coal mine in Guizhou Province, China. Mine opening is approximately 0.5 m wide. Note the absence of timber supports. Coal in the vicinity of this mine contains 35,000 parts per million (ppm) arsenic (As)! U.S. coal has, on average, 20 ppm As. Also nearby is a small gold mining operation. Some of the coal samples have ore grade concentrations of gold (600 ppb to 3 ppm in the coal ash).

Figure 7. The coal is primarily used in open, unvented ovens in homes for cooking, heating, and to boil water. In the fall, foods are brought indoors and dried over the ovens because it is too cool and damp for them to dry outdoors. Fresh chili peppers contain less than 1 ppm As. Chili peppers dried over the high-As coals have as much as 500 ppm As! While some As is inhaled during combustion, the majority enters the body when dried peppers are eaten in meals.

Figure 8. Consequence of eating food (and inhaling fumes) laden with As. The body tries to reject the As by moving it to the hair, fingernails, and urine. If that is not sufficient to purge the As, the body moves the As as far away from the internal organs as possible, to the hands, feet, and skin. The subtle signs of arsenism include a reddening of the skin and skin lesions, here appearing as freckles (melanosis).

Figure 9. Example of typically extensive keratosis (skin disease characterized by horny tissue overgrowths). Dark lesion above left breast was diagnosed as Bowen's disease -- a precancerous lesion of the skin or mucous membranes characterized by small solid elevations covered by thickened horny tissue.

Figure 10 (left). Hyperkeratosis of the feet. Note the dark, likely cancerous, lesions on both feet. Figure 11 (right). Advanced hyperkeratosis. Extensive lesions covering the hands are common.

Figure 12. Cancer of the thumb which was eventually amputated.		Figure 13.Cancer of the hand. Even though the hand was amputated, the patient subsequently died of cancer.

Figure 14. Although severe cases of cancer have become less common in recent years, these problems still persist. This photograph shows young boys in their home. Note the unvented coal-burning oven, scorch marks on the wall, and chili peppers drying over the stove.

Figure 15. This scanning electron photomicrograph shows a backscattered electron image of a polished block of arsenic-rich coal from Guizhou Province, China. Dark areas are coal, bright areas are minerals (mainly pyrite), milky-colored area is organically-bound arsenic.

Figure 16. Wavelength-dispersive X-ray map showing the distribution of arsenic in the sample depicted above (see fig. 15). Compare the distribution of the arsenic to the outline of the milky-colored area in the scanning photomicrograph. This indicates that the arsenic is found in the organic matrix of the coal, and not in the mineral (pyrite) fraction as is almost always the case.

Figure 17. Corn drying over an open, unvented coal-burning oven in a villager's house in Guizhou Province, China. Corn is thought to be the primary source of excess fluorine in the diet.

Figure 18. Villagers prepare briquettes by pulverizing moist coal containing 100 to 200 ppm F (in contrast, most coals worldwide have 50-100 ppm F). The pulverized coal is then mixed with clay to form briquettes to control combustion temperature and timing. The clay used is the residue of intense weathering of the local limestone. These local residual clays are typically enriched in F (commonly >1,000 ppm).

Figure 19. Dental fluorosis: mottling of the teeth is the most common consequence of ingesting high-fluorine corn products and breathing fluorine-rich emissions. About 10 million people in the region suffer from dental fluorosis.

Figure 20. Photograph showing skeletal fluorosis, resulting as spinal curvature, a common manifestation.		Figure 21. Consequences of fluorosis and vitamin D deficiency. Entire families have shown these symptoms.

Figure 22. Gathering about a coal fire at night. Exposure to polycyclic aromatic hydrocarbons from the incomplete combustion of the coal may lead to respiratory problems such as lung cancer. About 3.5 billion people worldwide are exposed to indoor air pollution such as this.