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.

HEALTH IMPACTS OF COAL: SHOULD WE BE CONCERNED?

It Depends

Probably not, if high quality coal coal beneficiated post combustion pollution control managed disposal practices |  |  | Definitely yes, if poor coal quality no beneficiation no pollution control residential use

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