Principal Research Results

Inhalation Risk Assessment of Trace Elements Emitted fromCoal-fired Power Plants
Background
Recently, the effects of chemical substances in the environment on human health and ecosystem have been a matter of concern. In order to protect living things from the effects, we have to assess the environmental risk that may cause the adverse health effects or ecological extermination. Up to now, the environmental impact of trace elements emitted from thermal power plants has beenassessed on the stack gas concentrations to the background concentrations. For fulfilling the scientific knowledge of environmental
impact of trace elements from power plants, health risk assessment for trace elements has been required. However there are no reports
which discussed the health risk of trace elements from power plants in Japan.

Objectives
To develop an inhalation risk assessment method for trace elements emitted from coal-fired power plants and assess the inhalation risks of trace elements for domestic coal-fired power plants.

Principal Results
1. Development of inhalation risk assessment method for trace elements
An inhalation risk assessment method for 16 trace elements (Table-1) from coal-fired power plants has been developed. Theinhalation exposure concentrations are calculated from the emission factor of trace elements and meteorological conditions measured
at power plants, atmospheric dispersion models used for regulatory purposes by the Japan Environmental Agency and inhalation exposure model introduced to consider a reasonably exposed individual in the Japanese population. By comparing the exposure concentrations with the inhalation risk factors recommended by the U.S. Environmental Protection Agency, individual carcinogenic risk, population carcinogenic risk and hazard index for noncarcinogenic risk were calculated (Figure-1).
2. Assessment of inhalation risks of trace elements from domestic coal-fired power plants
By applying the developed method to the 39 coal-fired power plants in Japan, the inhalation risks for trace elements were assessed. The individual inhalation carcinogenic risks for 6 trace elements from domestic coal-fired power plants were estimated to bebelow 5 × 10-8 and 2 orders of magnitude smaller than the health risk guideline of 1 × 10-5 (Figure-2). The inhalation hazard indexes
for 12 trace elements from domestic coal-fired power plants were estimated to be below 2×10-3 and 2 to 4 orders of magnitude smaller than the inhalation reference levels that an adverse health effect would not be anticipated. As a result of comparison between the inhalation risks of trace elements from coal-fired power plants with the accidental risk in daily life, the individual inhalation carcinogenic risks for coal-fired power plants are 2 to 7 orders of magnitude smaller than the daily risks and are well below the level thatwould not increase the daily risk significantly (Figure-3).

Future Developments
The results of inhalation risk assessment will be used as the fundamental materials in the risk communication for trace elements.
Main Researcher: Kazuo Asakura,
Senior Research Scientist, Atmospheric Environmental Sector, Environmental Science Research Laboratory
Reference
Kazuo Asakura et al.,2004, “Inhalation risk assessment of trace elements emitted from coal-fired power plants”, CRIEPI Report
T03032 (in Japanese)36

C. Harmonization of energy and environment

Table1 Trace elements selected for inhalation
risk assessmentNo.

Substances

12345678910111213141516

Arsenic
Beryllium
Cadmium
Chromium
NickelBenzo(a)pyrene
Boron
CobaltHydrogen chloride
Hydrogen fluoride
Mercury
Manganese
Lead
Antimony
Selenium
Vanadium

AsBe
Cd
Cr
Ni
Bap
B
Co
HCl
HF
Hg
Mn
Pb
Sb
Se
V

Carcinogenic

Noncarcinogenic

○○
○
○
○
○
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA

○
○
○
○
○
NA
NA
NA
○
○
○
○
○
○
○
NA

Trace Elements

Area Studied

Chemicals Data

Emission Data

Meteorology Data

Social Data

Atmospheric
Dispersion Model

Inhalation
Exposure ModelGround Level
Concentration

Exposure
CoeffcientInhalation
Concentration
Inhalation Risk
FactorPopulation

Carcinogenic
Risk

NA：Not Available on the information of carcinogen or
noncarcinogen

Noncarcinogenic
Risk

Fig.1 Inhalation risk assessment method of traceelements from coal-fired power plants

1.0
Annual Risk

0.9

10 −2

Fraction of Plants

Maximum：5×10−8

100.7

10 −4

0.6

10 −5

0.5

10 −6

0.4

10 −70.3

10 −80.2

10 −939 Power Plants (This Study)

1.0E-09

1.0E-0 8

1.0E-07

1.0E-0 6Cancer (2.4×10−3）
Sudden Accident (3.1×10−4）
Traffic Accident (7.6×10−5）Fire (8.5×10−6）
Natural Disaster (8.4×10−7）

Target Value Recommended
by the Health Risk Guideline

Air Accident (1.3×10−7）
Thunder (2.1×10−8）

Annual Individual Risk of
Coal-Fired Power Plants(This Study)
Max.：7×10−10

10 −10424 Power Plants (EPA)

0.0
1.0E-1 0Inhalation Carcinogenic Risk

−30.8

0.1Daily Death Risk(＊)

10 −11
1.0E-05

Min.：4×10−11(＊) White paper on police (2003), Vital statistics (2003)

Individual Inhalation Carcinogenic Risk

Fig.2 Distribution of individual inhalation
carcinogenic risk for coal-fired power

Fig.3 Comparison between individualinhalation
carcinogenic risk and daily death risk

plants
The individual inhalation carcinogenic risks of traceelements for 39 coal-fired power plants are 2 to 7
orders smaller than the daily death risk. These risks
are well bellow the level that would not increase thedaily risks significantly.

The individual inhalation carcinogenic risks of traceelements for 39 coal-fired power plants in Japan arebelow 5×10−8 and 2 to 3 orders smaller than thehealth risk guideline of 1×10−5. The risks of 39
power plants in Japan are well below the risks of
424 power plants in the U.S..

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