HEALTH IMPACTS OF COAL COMBUSTION: SHOULD WE BE CONCERNED?
Table 1. Main anthropogenic emission sources of trace elements in Europe in
1979
[Modified from Pacyna (1984)].
| Element | Main sources (% contribution to the total emission) |
|
|---|---|---|
| As | Metallurgical (82) | >coal combustion (7) |
| Be | Coal combustion (almost 100) | |
| Cd | Metallurgical (83) | >coal combustion (5) |
| Co | Oil combustion (58) | >coal combustion (43) |
| Cr | Metallurgical (80) | >coal combustion (13) |
| Cu | Metallurgical (61) | >coal combustion (12) |
| Mn | Metallurgical (84) | >coal combustion (11) |
| Mo | Coal combustion (70) | >oil combustion (29) |
| Ni | Oil combustion (60) | >coal combustion (17) |
| Pb | Gasoline combustion (60) | >metallurgical (34) |
| Sb | Coal combustion (74) | >refuse incinerators (25) |
| Se* | Coal combustion (50) | >oil combustion (39) |
| V | Oil combustion (almost 100) | |
| Zn | Metallurgical (73) | >refuse incinerators (17) |
| Zr | Coal combustion (almost 100) | |
| Coal has been cited as the main anthropogenic source for potentially toxic
trace elements. Note: no information on mercury is presented. See Appendix for a Periodic Table of the elements illustrating their health significance. |
||
| Table 2. Selected trace
elements emitted by coal-fired power stations with known toxic responses in
test systems and in humans. [U.S. Department of Energy] |
|
| Element | Health Effects |
|---|---|
| As | Anemia, gastric disturbance, renal symptoms, ulceration; skin and lung carcinogen in humans; a suspected teratogen (birth defects) |
| Be | Respiratory disease and lymphatic, liver, spleen, and kidney effects; an animal and probable human carcinogen |
| Cd | Emphysema and fibrosis of the lung, renal injury, possible cardiovascular effects; an animal and possible human carcinogen; testicular toxicity in mice and rats; teratogenic in rodents |
| Hg | Neural and renal damage, cardiovascular disease; methylmercury is teratogenic in humans |
| Mn | Respiratory and other effects |
| Ni | Dermatitis, intestinal disorders; Ni and nickel oxide dusts are carcinogenic to guinea pigs and rats; nickel refining is associated causally with cancer in humans |
| Pb | Anemia, cardiovascular, neurological, growth retarding, and gastrointestinal effects; some compounds are animal and possible human carcinogens; fetotoxic and probably teratogenic to humans |
| Se | Gastrointestinal disturbance, liver and spleen damage, anemia; a possible carcinogen, a suspected teratogen |
| V | Acute and chronic respiratory dysfunction |
| Trace elements can cause a wide range of health problems. Note: dose, speciation, and exposure pathways (ingestion, inhalation, contact with skin, etc.) are some of the critical factors that influence the toxic response. Specific variations in these factors were not considered in this table. | |
| Table 3. Potential hazardous air pollutants
(1990 Clean Air Act Amendments) [Coal data from Finkelman (1993). See Appendix for complete list of element concentrations in U.S. coal.] |
||
| Element | Presence in coal (ppm) |
Maximum potential annual emission (tons) |
|---|---|---|
| As |
24 |
24,000 |
| Be |
2.2 |
2,200 |
| Cd |
0.5 |
500 |
| Cl |
600 |
600,000 |
| Co |
6 |
6,000 |
| Cr |
15 |
15,000 |
| F |
100 |
100,000 |
| Hg |
0.2 |
200 |
| Mn |
43 |
43,000 |
| Ni |
14 |
14,000 |
| Pb |
11 |
11,000 |
| Sb |
1.2 |
1,200 |
| Se |
2.8 |
2,800 |
| U |
2.1 |
2,100 |
| Compared to crustal abundances, many trace elements are concentrated
in coal. Although these elements are present at part per million (ppm)
levels in coal, the 1 billion tons of coal used annually in the United
States could mobilize significant amounts of these elements. But are the maximum potential annual emission estimates realistic? |
||
|
Table 4. Progressive trace element enrichment
in a coal-fired power plant (ppm) [Kaakinen and others (1975_. Samples were collected at a 180-MW unit. |
||||||||
| Sample | Cu | Zn | As | Mo | Sb | Pb | Se | Hg |
|---|---|---|---|---|---|---|---|---|
| Coal |
9.6 |
7.3 |
-- |
0.99 |
-- |
-- |
1.9 |
0.070 |
| Bottom ash |
82 |
58 |
15 |
3.50 |
2.8 |
<5 |
7.7 |
0.140 |
| Precipitator ash (inlet) |
230 |
250 |
120 |
41.00 |
14.0 |
66 |
27 |
0.310 |
| Precipitator ash (outlet) |
320 |
370 |
150 |
60.00 |
18.0 |
130 |
62 |
-- |
| Volatile elements such as Hg, Cl, and F are largely released with the flue gas. However, most other elements are concentrated in the coal combustion by-products, especially the fly ash that can be captured by electrostatic precipitators or fabric filters (bag houses). | ||||||||
| Table 5. Effect of fly ash particle size on the concentration
of some trace elements
(ppm) [Ondov and others (1979)] |
||||
| Size range (_m) | ||||
|---|---|---|---|---|
| Element | >15 | 8-15 | 3-8 | < 3 |
| As |
13.7 |
56 |
87 |
132 |
| Be |
6.3 |
8.5 |
9.5 |
10.3 |
| Cd |
0.4 |
1.6 |
2.8 |
4.6 |
| Co |
8.9 |
16.3 |
19 |
21 |
| Cr |
28 |
49 |
59 |
63 |
| Cu |
56 |
89 |
107 |
137 |
| Ga |
43 |
116 |
140 |
178 |
| Mn |
207 |
231 |
261 |
317 |
| Mo |
9.1 |
28 |
40 |
50 |
| Ni |
25 |
37 |
44 |
40 |
| Pb |
73 |
169 |
226 |
278 |
| Sb |
2.6 |
8.3 |
13 |
20.6 |
| Se |
19 |
59 |
78 |
198 |
| U |
8.8 |
16 |
22 |
29 |
| V |
86 |
178 |
244 |
327 |
| W |
3.4 |
8.6 |
16 |
24 |
| Zn |
71 |
194 |
304 |
550 |
|
Most trace elements are highly concentrated in the finest (respirable) fraction of the fly ash. Most researchers attribute this phenomenon to condensation on the large surface area. However, there may be other causes for this phenomenon. |
||||
| Table 6. Average percent removal [Finkelman and French (1998)] |
|||
| Element | Coal cleaning |
In boiler |
Post combustion |
|---|---|---|---|
| As |
45 |
43 |
97 |
| Be |
65 |
98 |
|
| Cd |
38 |
60 |
85 |
| Cr |
49 |
50 |
97 |
| F |
50 |
||
| Mn |
56 |
98 |
|
| Pb |
55 |
52 |
93 |
| Hg |
21 |
8 |
|
| Ni |
43 |
25 |
|
| Emission into the atmosphere of a significant proportion of many trace elements can be reduced by selective mining, coal cleaning, differentiation in the boiler, and by post combustion pollution control systems. | |||
| Table 7. Percent of atmospheric emissions (1990) [EPA, Finkelman and French (1998)] |
|
| Element | Percent |
|---|---|
| Pb |
1.5 |
| Ni |
2.5 |
| Cd |
2.5 |
| As |
4.0 |
| Cl |
5.0 |
| Hg |
34.0 |
| Se |
37.5 |
|
These data indicate that coal combustion
contributes only modest amounts of most trace elements into our atmosphere. |
|
| Table 8. Known health effects of trace elements in coal | |
Trace elements |
Known health effects |
|---|---|
| Arsenic | China – skin cancer ~10,000 people Former Czechoslovakia – impaired hearing in children |
| Fluorine | Fluorosis affects 10 million+ in China |
| Selenium | Selenosis in China Fish kills – Texas, NorthCarolina |
| Mercury | Various health problems in pregnant women and populations eating Hg-contaminated fish |
| Beryllium | Increased autoantibodies – former Czechoslovakia |
| Uranium | None known |
| Table 9. Predicted cancer fatalities due to ionizing radiation: General population, average dose (assume one cancer fatality per 5000 person-rem) | |||
Radiation fatalities |
|||
|---|---|---|---|
mrem/yr |
Total number in U.S. per year |
Per million persons per year |
|
| Medical diagnostic |
70 |
3080 |
14 |
| Cosmic radiation |
35 |
1540 |
7 |
| Terrestrial (rocks, soil, etc.) |
35 |
1540 |
7 |
| Potassium-40 in food |
20 |
880 |
4 |
| Nuclear weapons fallout |
4.4 |
194 |
0.9 |
| Use of natural gas in homes |
2 |
89 |
0.4 |
| BURNING OF COAL |
1 |
44 |
0.2 |
| Sleeping with another person |
0.1 |
4.4 |
0.02 |
| Nuclear power |
0.1 |
4.4 |
0.02 |
| Consumer products (TV, etc.) |
0.03 |
1.3 |
0.006 |
|
There are relatively few cancer fatalities
attributed to ionizing radiation from coal combustion. |
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HEALTH IMPACTS OF COAL: SHOULD WE BE CONCERNED?
It Depends
Probably not, if
|
Definitely yes, if
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