1 

Manganese 

 From Wood-Fired Boilers

Dan Ahern PE 

March 2004
2 

Acknowledgments 

This document was prepared under EPA’s Office of Research and Development’s 

(ORD) program called the Regional Research Partnership Program (RRPP). This 

program provides short-term training opportunities for EPA Regional Office Staff to work 

directly with ORD scientists at ORD laboratories. 

The primary scientists assisting on the project were David Tingey and Bill Hogsett of 

ORD’s National Health & Environmental Effects Research Laboratory (NHEERL), 

Western Ecology Division in Corvallis Oregon. They were the mentors for this study 

and provided direction and assistance during the study. The Western Ecology 

Laboratory provided workspace and logistic support during the initial development of the 

project activities. 

There were a number of other scientists at ORD labs that provided assistance in this 

study. They included: 

Ken Hudnell of NHEERL in Research Triangle Park (RTP) on medical effects of 

manganese. 

Joe Behar of National Exposure Research Laboratory (NERL) in Las Vegas on 

manganese mobile source issues. 

John Kinsey, Dean Smith and Michael Hayes of the National Risk Management 

Research Laboratory (NRMRL) at RTP on wood stove and prescribed burning issues. 

There were an number of other parties that provided data and insight during this review 

and they are listed in the contact list in attached contact list. 

The Air, Pesticides and Toxic Management Division Director, Beverly Banister, provided 

the time and support in the Atlanta Regional Office to complete this study. 
3 

Contents 

1. Executive Summary 4

2. Background 5 

3. Manganese Sources and Effects 6 

4. Medical Effects of Manganese 7 

5. Manganese and Plants 12 

6. Emissions of Manganese from Burning 19 

7. Manganese Emissions and Air Quality 22 

8. Summary and Conclusions 25 

Appendix 1 - References 27 

Appendix 2 - Contacts 31 
4 
5 

Executive Summary 

Manganese and Wood-Fired Boilers

Manganese is widely distributed in earth’s rocks and soil. It is the twelve most abundant 

element. Consumption of Manganese is primarily (90+ %) attributed to steelmaking and 

other metallurgical uses, with other uses being in dry cell batteries, animal feed, plant 

fertilizer, and water treatment chemicals. 

High levels of Manganese exposure leads to a neurologic disease called manganism. 

Manganism symptoms include dull affect, altered gait, fine tremor and sometimes 

psychiatric disturbances. Concern for Mn exposure seems less than its low inhalation 

Minimum Risk Level (MRL) would call for. Studies on Mn have been mainly in the 

occupational area and due to the lack of data on effects to potentially susceptible 

populations, there is a high safety factor built into the development of the MRL. It 

certainly seems that further medical research is needed to determine if this low MRL is 

justified and determine a MRL with a reasonable safety factor. 

Manganese has been linked to violent behavior in young adults and learning impacts on 

children. Occupational and follow-up studies show that Mn exposure effects are 

permanent and progress even after exposure has ceased. While the long-term effect of 

exposure is the development of manganism, which is a disabling syndrome of 

neurological effects, many relatively mild symptoms occur early on in the exposure. 

It appears that Mn is the primary HAP metal in wood/bark used in wood-fired boilers. 

Levels in bark appear higher than in trunk wood and Mn levels in leaves can vary by 

orders of magnitude with levels running from 1 to over 1000 ppm. Existing data does 

not reveal this range in wood and bark, used in boilers, where the range of levels ran 

from 4 to 184 mg/kg. Current data is not sufficient to say that certain species or 

geographic areas will have different levels of Mn in their wood/bark. This would be a 

good area for future study since the limited data indicates possible differences. 

Mn is by far the HAP metal emitted in the greatest amount, from wood-fired boilers. It 

accounts for over 90% of the HAP metal emissions from burning wood. Most woodfired boilers will be covered by an upcoming MACT standard and will be required to 

provide particulate control. This will also reduce Mn emissions. The controls will reduce 

Mn emissions to levels experienced in wood-stoves and fireplaces. There is need to 

determine emission factors for Mn from wild fires and prescribed burns. 

There is not a good correlation between ambient air concentrations of Mn and reported 

TRI releases. There appears to be a lack or coordination between reported emission 

inventory data and what is being reported in TRI reports. Mini-steel mills and metal 

foundries need further investigation to better estimate emissions of Mn from their 

operations. 
6 
7 

Background 

The reason for this study was work performed by the EPA Region 4 Toxic Release 

Inventory (TRI) Staff on a new modeling program from EPA’s Office of Pollution 

Prevention and Toxics called the Risk-Screening Environmental Indicators (RSEI). This 

model supplements a quantity-based view of the TRI releases by incorporating toxicity 

information and exposure models that assess, at a screening-level, the relative-risk that 

chemicals released may pose. This unpublished report entitled “US EPA Region 4 

Relative Risk Initiative, 1999 TRI Air Release Data” (1) reported that Manganese (Mn) 

compounds was the number one chemical when ranked by the RSEI relative-riskrelated value. It ranked in the top five chemicals in seven of the eight Region 4 states. 

This new data from our TRI staff was of great interest because Manganese and 

Manganese Compounds were not part of any ongoing P2 activities. Further work with 

the TRI staff on industrial sectors contributing to Manganese releases, indicated that a 

number of sources were from wood-fired boilers. Wood-fired boilers are used 

extensively in Lumber (SIC 24), Furniture (SIC 25) and Paper (SIC 26) sectors. Region 

4 averages (1999-2001) about 45 of the top 100 TRI reporting facilities in these sectors 

reporting Manganese and Manganese Compound releases. 

 One significant annual increase in reported Mn emissions came from a facility that had 

a wood-fired boiler. Upon investigation, the facility reported raising its emission factors 

based on input from a sector technical support group. (2) 

This combination of a newly-identified chemical risk, the large number of these sources 

in Region 4, and possible understating of emission factors from wood-fired boilers, 

leads to a need for better understanding of the risk and the actions that could be taken 

to reduce this risk. 

Very little information could be found initially on Manganese emissions from wood-fired 

boilers and the region could not idenify programs already looking into issues with Mn. 

To dedicate some time to this regional concern, a proposal was submitted under the 

Regional Research Partnership Program (RRPP) to study Manganese levels in wood 

fuels obtained from various forest types and determine if they vary with geography and 

or soil types. 

EPA’s Office of Research and Development (ORD) accepted this proposal and ORD’s 

Western Ecology Lab in Corvallis, Oregon agreed to support this study. 
8 

 Manganese 

Sources and Effects 

Manganese was first recognized as an element and isolated in 1774. It is a metal that 

from a chemical standpoint is related closely to iron. From a metallurgical standpoint, 

manganese differs from iron (and its other atomic neighbors - cobalt and nickel) in that it 

does not possess useful physical properties as relatively pure metal. Its principle 

industrial application is to serve as an alloying element. 

Manganese is widely distributed in the earth’s igneous, sedimentary, and metamorphic 

rocks. It has been calculated to be the twelfth most abundant element on the earth’s 

crust. Only aluminum, iron, magnesium, and titanium metals are more abundant than 

manganese.(3) 

Manganese has been used in making steel since 1839, but did not come into general 

use until the later part of the 19th century with greater use of the Bessemer Process. 

The domestic consumption of manganese is primarily (90+%) attributable to 

steelmaking and other metallurgical uses. Manganese is also used in dry cell batteries, 

animal feed, plant fertilizer and water treatment chemicals.(4) 

About 700,000 metric tons of Manganese was used in 2001. (5) None of this metal is 

mined in the US. Only one plant in this country processes manganese into 

ferromanganese ores to be used in steel making, all other processed ores are imported. 

The first report of human illness due to manganese was identified in 1837 and later 

rediscovered in the twentieth century. Manganese is an essential nutrient for plants and 

animals, but at higher exposure levels is a neurotoxin in humans. The most critical 

exposure is from inhalation that seems to bypass the human ingestion barriers to impact 

the central nervous system.(6) 

Manganese material flow pattern work by the Department of Interior (4) estimates that 

air emissions of manganese has increased 45% due to human activities. They list the 

following anthropogenic sources as energy production (coal and oil combustion); 

mining; smelting and refining; steel and iron manufacturing; and waste incineration. 

Most material flow work does not consider manganese emissions from anthropogenic 

wood burning, even though the Department of Interior estimate that the manganese 

emissions from forest fires is greater than the world-wide emissions from steel and iron 

manufacturing. 
9 

Manganese is identified as a priority candidate chemical by Centers for Disease Control 

and Prevention, for inclusion in the National Report on Human Exposure to 

Environmental Chemicals.(7) 

Medical Effects of Manganese

Manganese (Mn) is considered an essential element both for humans and plants. 

Humans are exposed to Mn in food and water they eat and drink and in the air they 

breathe. It is considered an essential nutrient because of its involvement in many of the 

body’s enzymatic reactions. (6) Diets with too little Mn can lead to slowed blood clotting, 

skin problems, changes in hair color, lowered cholesterol levels and other alterations in 

metabolism (8). There is a lack of consensus about the recommended daily 

allowances, but normal diets seem to provide the necessary levels of Mn. (3) 

There seems to be a narrow line between the recommended Mn requirements (2-5 

mg/day) and the oral Reference Dose (RfD), which is ~ 10 mg/day for a 70 kg 

person.(6) It seems that the body processes the dietary Mn that it needs and the excess 

is excreted in the feces. Inhaled Mn behaves differently, it bypasses the body’s liver 

and blood-brain barrier and accesses the Central Nervous System (CNS) directly. 

High exposure to Mn, via inhalation, causes a neurologic disease called manganism. 

First noted in manganese miners, this disease has a combination of symptoms that 

include mental and emotional disturbances and slow and clumsy body movements. 

Although similar to Parkinson symptoms, it is a different disease. These effects are 

caused by brain damage and the brain injury is permanent (8). A number of effects that 

have been identified in occupational workers that are less severe and have been related 

to exposure to lower levels of Mn. There are a number of epidemiological studies of 

workers exposed to Mn below the American Conference of Governmental Industrial 

Hygenists Threshold Limit Value that have shown neurobehavioral, reproductive and 

respiratory effects(9). The inhalation RfD was established based on the work of Roels et 

al in 1992 (10) on the detected preclinical neurological effects. These effects included 

visual reaction time, eye-hand coordination and hand steadiness. 

There appears to be no evidence to determine whether or not Mn is carcinogenic and 

some reports that suggest that it may even be protective against cancer (9). Therefore 

EPA considers Mn to have only potential for chronic noncancer effects. 

The inhalation Reference Dose (RfC) and the Minimal Risk Level (MRL) developed by 

the Agency for Toxic Substances and Disease Registry (ATSDR) of CDC for Mn is 

lower than some of the other perceived high risk metals. Table 1 below compares the 
10 

inhalation MRL and Reference Doses (RfD) for selected metals based on ATSDR’s 

toxicological profiles for these substances http://atsdr1.cdc.gov/toxpro2.htm It is 

surprising that the RfD for Mn is six times more stringent than that for Mercury. This 

does not match what the States have established as acceptable ambient concentrations 

in their air regulations and guidelines. In fact, in one Region 4 state, the acceptable 

ambient Mn level was 25 ug/m3 and the mercury level was 0.25 ug/m3. The level of 25 

ug/m3 for Mn is 500 times the RfD of 0.05 ug/m3! The mercury level of 0.25 ug/m3 is 

below the RfD of 0.3 and above ATSDR MRL level of 0.2 ug/m3. 

The low values for Mn are in great part due to the high level of uncertainty in taking the 

Lowest Observed Adverse Effect Level (LOAEL) or No-Observed Adverse Effect Level 

(NOAEL) to the reference dose or minimal risk level. Table 1 indicates that the safety 

factor for Mn is nearly an order of magnitude higher than the other metals and this 

reflects a number of unknowns about Mn. This higher factor reflects the lack of studies 

on Mn for groups other than in occupational studies and other uncertainties with existing 

data. This low inhalation value for Mn has not filtered down to State Acceptable Ambient 

Air levels or other reduction initiatives that exist for mercury and lead. 

Table 1 

Comparison of Inhalation MRL and RfD for Selected Metals

Uncertainty

Metal MRL RfD Factor State Acceptable Ambient 

Range

ug/m3 ug/m3 ug/m3 

Manganese 0.04 0.05 2100 0.24 to 119 

Mercury 0.2 0.3 125 0.01 to 0.75 

Lead* 0.14 210 0.09 to 1.5 

Chromium IV 0.005 0.008 400 0.0001 to 0.3 

* MRL not derived by ASTDR. EPA did not generate an RfD that it feels inappropriate 

because some health effects associated with exposure to lead 

occur at blood levels as low as to be essentially without threshold. 

OSHA established action level of 30 ug/m3 for workplace exposure. 

The imputed MRL for lead was developed by applying the 

manganese uncertainty factors except for “an uncertainty factor of 

10 to account for limitations in the inhalation database, including 

the lack of data on developmental effects and data on the potential 

for reproductive effects in women, and potential for differences in 

toxicity from different forms of manganese”. 

As mentioned above, inhaled Mn bypasses the liver and blood-brain barrier that 

ingested Mn is subject to and accesses the CNS directly. Originally only the fine Mn 

fraction was thought to pose substantial human-health risk due to its ability to reach 
11 

deep in the lung, but some researchers have discovered another access to the CNS via 

coarse fraction Mn deposited in the nasal mucosa.(11) 

The medical impact of Mn seems to correlate with some effects of lead. There seems 

to be three separate impacts from excessive Mn exposure and they relate to children, 

young adults and long term occupational or area exposure. 

Effect of Mn exposure on Children 

Most manganese studies have been in occupational studies. Some limited studies on 

children show increased respiratory complaints and learning problems. A study in 

China indicated lower 

mental performance in students exposed to higher levels of manganese. Investigations 

showed that students who performed poorer in school had higher manganese hair 

content than children in a control group (8). These studies are not sufficient to establish 

cause-effect relationship since a number of other agents, including lead might also be 

involved. Other studies indicate that infants and children may be more susceptible to Mn 

exposure because they retain a much higher percentage of ingested or injected Mn than 

adults. Formulas for infants contain higher levels of Mn than breast milk, but apparently 

no studies suggest whether this is unhealthy or not. 

Effect of Mn exposure on young adults 

A number of researchers have hypothesized that violent behavior is associated with 

excessive body burdens of Mn and other metals like lead and cadmium. The 

hypothesis holds that a certain percentage of the population can not properly handle the 

environmental loading of metals and this group accumulates higher levels of heavy 

metals. These higher levels lead to violent behavior. One researcher (Needleman) 

estimates that 11 to 38 percent of all violent crime can be traced back to these 

metals.(12) Another researcher measured significantly higher Mn levels in several 

groups of prisoners held for violent crimes than nonviolent prisoners and other control 

populations (6). Master et al (13) compared the Toxic Release Inventory (TRI) release 

figures and the Federal Bureau of Investigation (FBI) violent crime database. After 

controlling for many socioeconomic and demographic variables they showed significant 

positive associations between releases of Mn and lead and increased violent crime 

rates. Masters also reported that dietary deficits of calcium and zinc and other essential 

vitamins can lead to greater adsorption of Mn and lead. It would be very interesting to 

see research on using these supplements to see if this would reverse the Mn and lead 

levels and possibly show changes in behavior of violent criminals. Masters also 

reported that Lithium has been found to detoxify manganese. 

This hypothesis has considerable import for work ongoing that is studying the potential 

effects of a gasoline additive called Methylcyclopentadienyl Manganese Tricabonyl 

(MMT). This additive, which is prohibited in the US, is used in Canada. Masters reports 

that the since the introduction of MMT in Canada, the rate of all violent crimes has 
12 

increased at a faster rate in Canada than in the US. US EPA Office of Research and 

Development is conducting another reevaluation of the risks of MMT that will update 

their 1994 study (9). This study should be released in 2004. 

It is difficult to separate the impacts of Mn and Lead. Masters included both, in his 

work. Another researcher Nevin (12) reported a strong association with a drop of 

murders committed by children under the age of 18 with the exposure reduction of lead 

with a lag of 23 years. It is cause of concern for these researchers that Mn could step in 

the void left from the elimination of lead in gasoline. 

Unfortunately Masters did his work utilizing TRI data and missed the highest ambient 

Mn level recorded in the US. This town, East Liverpool, Ohio, did not have Mn releases 

reported in TRI. As will be discussed later, there are some unexplained gaps in TRI 

emission figures and measured ambient air levels. Table 2 compares three towns in 

Ohio that had ambient air monitoring stations. 

East Liverpool, Ohio has the dubious distinction of having the highest recorded ambient 

level of Mn in the nation. Unfortunately, TRI data showed few reported releases. This 

town had no reported releases from facilities in town and only about 600 lbs from the 

surrounding county. Another town, Marietta Ohio also has a dubious distinction of 

having the only remaining Ferro-manganese alloy plant and has the highest reported 

TRI air releases of Mn in the country. This plant reported releasing 431,000 lbs of Mn in 

2000. 

Table 2 does not indicate a good correlation between ambient Mn levels and FBI violent 

crime statistics. All three towns have low crime rates and the rate per thousand people 

in E. Liverpool is not significantly higher (1.7 vs 1.3) than Bellefontaine, which had low 

ambient Mn level. 

Additional work was done with South Carolina statistics. This state has one of the 

better ambient air monitoring networks. Limited review seemed to indicate some 

correlation but it was hampered by lack of FBI statistics in that state (The city with the 

highest ambient Mn levels had no statistics in the FBI database). Ken Hudnell at ORD 

NHEERL has done some additional work in this area and by including other crime 

statistics like domestic violence and other assault figures, did get a better association 

comparing Marietta with Athens, Ohio. 

Table 2 

Ambient Manganese level and FBI Violent Crime Rates

2000 Ambient Air Data and FBI statistics 

Item/City Bellefontaine Marietta E. Liverpool 

Population 13,092 14, 541 13,113 
13 

Median Income $36,029 $29,863 $23,138 

Ethnic Diversity 92.4%Cau 98.2%Cau. 94% Cau. 

Murder 0 0 0 

Rape 10 9 6 

Robbery 4 4 11 

Aggr Assualt 3 8 5 

TSP Mn Levels ND* 0.4ug/m3*** 0.7-1.5ug/m3** 

(Annual Average) 

* no detect (below 0.1ug/m3) at monitoring station (11 samples) 

** Two monitoring sites 

*** State site data not on national air quality system 

Effects of Long term Mn Exposure 

Again most of the research and studies have been occupational but it appears that 

damage is permanent and therefore may be cumulative. ATSDR list those over 50 as a 

more susceptible population to the adverse effects of manganese exposure. The 

Toxicological Profile for Manganese list numerous studies on the effects of Mn(8) Some 

follow-up studies suggest that there is continuing deterioration of health after exposure 

had ceased. Huang et al (14) reported that workers in a ferroalloy plant that were 

chronically exposed to Mn continued to show progression of clinical symptoms of 

manganism, 9 to 10 years after exposure had ceased. Their levels of manganese in 

blood, urine, scalp and hair revealed a drastic drop in manganese concentrations but 

their health continued to decline. Some other studies report that impaired sexual 

function may in men may be the earliest clinical manifestations of manganism. Many 

studies indicate impotence and lack of sexual desire were higher in groups exposed to 

Mn. 

There does not seem to be many long term follow-up studies for effects of Mn exposure. 

The aging process may mask the sub clinical effects of manganism. The similarity 

between some symptoms of manganism and Parkinson diseases may lead to confusion 

and better differentiation between the two may be needed. Despite the similarities, 

significant differences exist between the two. Hopefully future epidimiologic studies will 
14 

determine rates in older populations so that appropriate attention and identification can 

be given to long term exposure. 

Summary 

High levels of Manganese exposure leads to a neurologic disease called manganism. 

Manganism symptoms include dull affect, altered gait, fine tremor and sometimes 

psychiatric disturbances. Concern for Mn exposure seems less than its low inhalation 

RfC and Minimum Risk Level (MRL) would call for. Studies on Mn have been mainly in 

the occupational area and due to the lack of data on effects to potentially susceptible 

populations, there is a high safety factor built into the development of the MRL. It 

certainly seems that further medical research is needed to determine if this low MRL is 

justified and determine a MRL with a reasonable safety factor. 

Manganese has been linked to violent behavior in young adults and learning impacts on 

children. Occupational and follow-up studies show that Mn exposure effects are 

permanent and progress even after exposure has ceased. While the long-term effect of 

exposure is the development of manganism, which is a disabling syndrome of 

neurological effects, many relatively mild symptoms occur early on in the exposure. 

Manganese and Plants

 One of the initial investigative questions in this review was “How much Mn Comes into 

the Wood-fired Boiler”. The reviews in this area tried to determine if the Mn levels in 

wood was different for different species and for different soil conditions. 

Manganese is widely distributed in the earth’s rocks and has been calculated to be the 

twelfth most abundant element in the earth’s crust. (3) The average concentration of 

manganese in soil from one reference is 800 ppm. The US Geological Survey collected 

soil samples in 1961 from 863 sites in the continental US and the amount of manganese 

varied from 2 to 7000 ppm with an arithmetic mean of 560 ppm. Manganese is 

considered a micronutrient (essential but needed only in small amounts) for plants and 

has functions in many plant processes.(15) 

The availability of Mn to plants is affected by numerous soil characteristics like total or 

easily reducible manganese; pH; concentrations of other cations; organic-matter 
15 

content; drainage; compaction; temperature; and microbial activity, of these the pH 

seems to be a primary factor. Plants absorb manganese primarily in the divalent state 

and lowering the pH favors the reduction of manganese to this form and thereby 

increasing its solubility and availability. Small changes in these soil characteristics can 

determine whether the available Mn will be deficient, adequate or toxic for a given crop. 

Once taken up and incorporated into plant tissue, manganese is relatively immobile in 

the plant. (16) 

There is considerable data on Mn levels in food. This data indicates that different 

species of plants concentrate Mn at different levels varying from Apricots at 0.2 ug/g to 

tea at 275.6 ug/g. More data on levels in food are shown in Table 3.(3) 

Table 3 

Manganese in Food

Item Manganese Conc. Range High Low 

ug/g 

Grains and Cereals 1.42- 17.8 Barley Rice 

Fruit 0.20- 4.68 Raisins Apricot 

Nuts 0.38- 35.1 Pecans Coconut 

Vegetables 0.24- 12.7 Peas Green beans 

Misc. 0.95- 275.6 Tea Garlic 

The question now becomes does Mn levels vary between species of trees with the 

same soil characteristics, since it will vary between different species of plants. 

Considerable research has been conducted on the right balance of pH and available Mn 

on trees to prevent deficiency or toxicity. Unfortunately most research on trees studied 

the deficiency or toxicity based on Mn in 

 

leaf samples. Very little data were found to relate levels in tree leaves to levels in the 

wood or bark. Data on testing indicates that trees exhibit a deficiency of Mn when their 

leaf/needle levels get below 20 ppm. Adequate range is around 30 to 300 ppm range. 

Tree toxicity is indicated with leaf values over 400. Some testing showed levels as high 

as 2000 ppm in trees suffering toxic levels of Mn. A sample of test results from various 

sources is presented in table 4. 

Table 4 

Deficient, Adequate and Toxic Manganese Concentration in Plants

Leave samples in ppm (dry wt) 
16 

Data from Reference (P) unless noted 

Tree Deficient Adequate Toxic

Almond 5-25 96 ---- 

Apple 15 30 400 

Apple(17)(18) 25-100 540-865 

Orange 15-19 20-200 100-1000 

Pecan ------ 141-196 ------ 

Avocado(19) 232-950 2000 

Frazer Fir(20) 11 30-300 

Black Walnut(21) 25 46-500 750 

Silver Fir(22) (ug/g) 1.5-3.7 30-526 

The big question is; Are these varying levels in leaves reflective of the levels in wood 

and bark? Unfortunately this can not be answered. While much work was done on 

leave/needle concentration, only one source was found that measured both needle and 

woody shoots(22). This work in Switzerland did detailed work on both healthy and Mndeficient trees. This research clearly shows the impact of pH on Mn levels in needles 

and woody shoots. There is nearly a two order magnitude difference in Mn levels from 

deficient trees in high pH areas and those with lower pH area. Since this work was all 

on one species of tree it is a good indicator that Mn level in needles/shoots in similar 

trees can vary based on soil conditions. This research also shows that there is some 

modification in Mn between needles and shoots. Shoots tend to have lower Mn levels 

than high Mn needles and higher Mn levels than deficient tree needles. Studies were 

not found that looked into whether this modification is carried on further in the trunk 

wood and bark. Lower levels in bark and wood samples indicate this might be taking 

place. The data from the Switzerland study is presented in Table 5 

Table 5 

Mn Concentration in Needle and Shoots of Silver Fir Trees

Mean values in ug/g 

 Year Plant Part Healthy Trees Mn-Deficient Trees

Group A Group B Group C Group D 

1992 Needles 30.29 2.35 1.5 

1992 Shoots 18.47 3.47 4.38 
17 

1994 Needles 526 46.8 3.76 1.82 

1994 Shoots 478 23.3 2.81 3.02 

1994 Soil pH 3.7-4.4 5.8-6.5 7.0-7.1 7.0-7.1 

 

While there were no studies found that measured modification of Mn levels from leaves 

to trunk wood and bark, data on bark and wood Mn levels do not show the high variation 

found in leaves and needles. Bark and wood data by the National Council for Air and 

Stream Improvement (NCASI) that supports the paper industry shows a much lower 

range of variation than the leaf data. No data was found that came close to the 478 ug/g 

values in healthy shoots in the Silver Fir Study. 

The NCASI and American Furniture Manufacturer’s Association (AFMA) (23) data are 

presented in Tables 6 and 7 below. The NCASI data indicates that Bark samples 

generally contain higher levels of Mn than the wood chips. Unfortunately there was not 

enough data to make conclusions on the geographic location or the type of tree the 

samples came from. The limited data does indicate that the Southeast samples are 

higher and that Aspen and Fir samples show the lowest levels on Mn. While these data 

were not sufficient to draw conclusions about Mn levels being impacted by geographic 

area, a study on another boiler fuel gives strong evidence of variation. The Sugarcane 

Industry uses cane waste called Bagasse in their boilers. While not a tree fuel, it has 

similar heat content and is burned in similar boilers as the wood fired ones. A study on 

stack test results (24) reported that average Mn content of Bagasse in three Louisiana 

Mills (32.4 ppm) to be nearly three times as high as three Florida Mills (11.7 ppm) 

Table 6 

NCASI Manganese Data

Geographic Area Manganese Levels in mg/kg 

(number of samples) Ave. Min. Max 

Wood

Northeast (1) 39.0 39.0 39.0 

Southeast (8) 47.5 14.0 78.0 

Midwest (7) 19.5 4.3 33.3 
18 

Northwest (8) 17.4 7.3 38.7 

Bark * 

Northeast (0) 

Southeast (1) 165.0 165.0 165.0 

Midwest (2) 90.8 75.7 106.0 

Northwest (6) 94.2 21.5 184.0 

* There may be opportunities to increase knowledge on Mn levels for bark. During this 

study, it was learned that NCASI was working with American Forest and Paper Product 

Industry to analyze about 300 bark samples collected from member firms from around 

the country. This was being done as part of a response to the proposed Industrial 

Boiler MACT. While presently they only plan to measure mercury and chloride in the 

samples, the availability of these samples offers an opportunity to increase the data 

base and observe species and geographic differences. 

The AFMA recently collected samples (22) because they felt that the wood being 

burned in their members boilers would have lower levels of metals than the mixed and 

dirty wood burned in Pulp Mill boilers. Most of the wood burned in their member firms 

was either sawdust or chips from the furniture manufacturing process. Most of their 

member firms had mechanical controls as opposed to the pulp mills who generally had 

ESP or wet scrubbers. The data showed similar results as the NCASI Southeast wood 

data.(AFMA aver - 46.2 and NCASI aver - 47.5). Most of the AFMA wood measured 

was from areas around the plants in NC and VA, with some from TN and PA, so it would 

be representative of Southeast. This similarity in values also seems to indicate that 

there would not be a significant difference in southeast species since the AFMA results 

are mostly hardwoods and the NCASI results are most likely from softwoods. 

Table 7 

Data From American Furniture Manufacturer's Association (AFMA)

October 14, 2003 report 

Facility Type of wood Wood Wood Bottom Ash Fly Ash

(location*) (wood chips) lb/MMBtu mg/kg mg/kg mg/kg

A Poplar & Ash 0.0046 39.6 9720 7110 
19 

A Poplar & Ash 28.4 

B 0.0038 29 8260 6620 

B 26.7 

C Mixed 0.0086 61.7 15,400 

 14,400 

C Mixed 64.9 

D dry mix 0.006 40.6 6450 10100 

D dry mix 48.1 

E hard various spec 0.0052 40.9 852 5680 

E hard various spec 36.2 

F Hard/soft 90/10 0.0067 48.8 6960 8180 

F Hard/soft 90/10 49.7 

G MixSolid & Plywood 50/50 0.01 69.2 10400 17400 

G MixSolid & Plywood 50/50 78.6 

H** Poplar/Oak/composite 60/30/10 0.0034 27.2 5630 5850 

H** Poplar/Oak/composite 60/30/10 23.2 

I Poplar/Cherry/Lenga 50/25/25 0.0076 57.8 6690 8150 

I Poplar/Cherry/Lenga 50/25/25 54.3 

J Chips/hoggedwood/dust 80/10/10 0.002 29.9 5850 

* Facilities located in NC and VA but wood from PA, NC, TN and VA 

** wood dust not chips 

The data above shows that levels of Mn in wood and bark may vary by species and 

geographic area. Is this level significant and are there other metals that may be more 

significant? Mn is not the only metal in wood products but of the Hazardous Air 

Pollutant (HAP) metals, it is by far the most common in wood. The data in table 8 from 

NCASI analysis of wood samples shows that Mn is at least an order of magnitude 

higher than any of the other nine HAP metals. With the exception on mercury that will 

be released as a vapor, no other HAP metals are of significance. The section on 

burning will discuss whether Mn levels are significant. 

Table 8 

Hazardous Air Pollutant Metals in Wood Samples 

Metal Number of Samples Average mg/kg Percent Detects* 
20 

Arsenic 25 0.23 23 

Beryllium 17 0.01 0 

Cadmium 23 0.11 31 

Chromium 26 0.22 24 

Cobalt 20 0.02 0 

Lead 22 0.58 25 

Manganese 34 33.6 100 

Mercury 23 0.86 87.5 

Nickel 22 1.06 45.5 

Selenium 15 0.71 33 

* values below quantification level added to average when analysis does not detect 

measurable levels 

Summary

It appears that Mn is the primary HAP metal in wood/bark used in wood-fired boilers. 

Levels in bark appear higher than in trunk wood and Mn levels in leaves can vary by 

orders of magnitude with levels running from 1 to over 1000 ppm. Existing data does 

not reveal this range in wood and bark, used in boilers, where the range of levels ran 

from 4 to 184 mg/kg. Current data are not sufficient to say that certain species or 

geographic areas will have different levels of Mn in their wood/bark. This would be a 

good area for future study since the limited data indicates possible differences. 
21 

Emissions of Manganese from Burning 

 Another investigative question in this review was to find out “what happens in the woodfired boiler?”. After looking at this question the investigation was carried further to 

determine, what happens in wood stoves/fireplaces and in prescribed burns and 

wildfires. 

Mn melts at 1245 C and boils at 1962 C. It has higher values than lead and lower than 

iron. Most boilers operate below 1000 C and the highest temperatures are around 1400 

C. Therefore emissions of Mn from boilers are as solid particulates. 

EPA’s Compilation of Air Pollution Emission Factors AP-42 (Chapter 1.6) has factors for 

Mn from Wood Residue Combustion in Boilers. These factors for HAP metals mirror the 

levels found in wood and Mn again constitutes over 90 % of the total emissions of these 

metals. The factors are given in table 9.(26) and indicate that Mn is by far the biggest 

contribution to Metal HAP emission. 

Table 9 

HAP Metals Emission Factors 

From Wood Residual Combustion

In Boilers

Metal HAP AP-42 Emission Factor, Fifth Edition

 (lb/MMBtu) 

Arsenic 2.2E-05 

Beryllium 1.1E-06 

Cadmium 4.1E-05 

Chromium 2.1E-05 

Cobalt 6.5E-06 

Lead 4.8E-05 

Manganese 1.6E-03

Mercury 3.5E-06 

Nickel 3.3E-05 

Selenium 2.8E-06 

Total 1.7E-03 

The Emission Factor for Mn was increased in the Fifth Edition of AP 42 to 1.6E-03 from 

an old 2/99 factor of 9.79E-04, by utilizing about 24 reported stack tests that showed a 

range from 9.66E-11 to 9.77E-03. (27) Data having 7 orders of magnitude range is 

unusual. It appears that emission measurements with and without controls were 
22 

included in the results. A recent stack test by the AFMA in August 2003 indicates a Mn 

emission rate of 3.82E-03 lb/MMBtu. This stack test also did a fuel analysis on this 

tested boiler and the average Mn content was 5.9E-03 lb/MMBtu. This indicates that 

nearly 2/3rds of the Mn in the wood goes up the stack. Most ash tests indicate more Mn 

in the Fly ash than the bottom ash (see table 7). One study in Canada indicated 90 

percent of the Mn was in the Fly ash. (37) The AFMA test (though not stated) must have 

been before particulate control from the boiler’s dust collector that was estimated to 

have an efficiency of approximately 50 percent. 

The four most common control devices used to reduce PM emissions from wood-fired 

boilers are mechanical collectors, wet scrubbers, electrostatic precipitators (ESPs) and 

fabric filters. The removal efficiencies of these control devices range from a low value 

of 35% for certain mechanical devices to 99 % for ESPs. Further evidence that the AP42 value included data from controlled emission tests is shown by comparing NCASI 

data from their technical bulletin (TB). Their mean value with mechanical control is 

higher(3.2E-03) than the AP 42 value of 1.6E-03. Table 10 shows the expected 

emissions utilizing controls. One to two order of magnitude reductions in expected 

emissions can be obtained with controls. 

Table 10 

Control Removal Efficiency and Estimated Emission Factors for Mn

Control Device Removal Efficiency Revised Emission FactorNCASI 

Values

%(GG) Lb/MMBtu TB858(mean) 

Mechanical Collectors 25-65 1.2E-03 - 0.56E-03 3.2E-03 

Wet Scubbers 85+ 2.4E-04 4.0E-05 

ESPs 90-99 1.6E-04- 1.6E-05 1.5E-04* 

Fabric Filters 80+ 3.2E-04 ND 

* Later work with an individual Pulp mill permitee indicated their emission factor to be 

3.25E-05 after ESP control, based on a stack test at similar boiler at another on of their 

company’s plant. 

Review of boilers by sectors indicates that most wood-fired boilers in the Pulp sector 

(SIC 26) have ESP controls. Many of the pulp mill boilers had high stacks (most over 

100 feet with some up to 250 ft high). Most boilers in the Furniture sector (SIC -25) 

have mechanical collectors. 

It was also reported (28) that the percentage of wood residue that was burned rather 

than sold increased between 1992-1997 in West Virginia. It is not known if this is a 

widespread or continuing trend. 
23 

The secondary question came up on what happens in wood furnaces and fireplaces that 

do not have the particulate control devices that boilers have. The impact Wildfires and 

prescribed burning on Mn emissions was also of some concern because of the 

Department of Interior’s Mn material flow from wild forest fires. This document (4) 

estimates worldwide emissions of Mn from forest fires as 23 thousand metric tons and 

the anthropogenic sources as 38 thousand metric tons. This report did not include 

wood-fired boilers and residential woodburning as an anthropogenic source. 

AP 42 has sections for Wildfires and Prescribed burns (Ch 13.1), Residential Wood 

Stove (Ch 1.10) and Residential Fireplaces (Ch 1.9). The only Mn emission factor given 

for these three sources is for Wood Stoves. These were given in lb/ton of wood and 

can be converted to lb/MMBtu with the conversion factor from the residential fireplace 

chapter of 17.3 MMBtu/ton. Utilizing this conversion gives emission factors ranging 

from 0.8E-05 lb/MMBtu to 1.2E-05 lb/MMBtu. This emission factor is two orders of 

magnitude less that for wood-fired boilers and is less than these boilers with the best 

controls. Wood stoves have more emission of particulates(PM10) than boilers and 

AP42 gives stove ranges from 0.84 to 1.77 lb/MMBtu, while the boiler range is given as 

0.2 to 0.5 lb/MMBtu. 

Why is Mn is emitted from wood-fired boilers and not from residential wood stoves? The 

hypothesis is boilers are very efficient and the particulates being emitted are mostly 

inorganic combustion products. In wood stoves the particulates are primarily 

recondensed organics and most of the metals stay in the bottom ash. This was 

supported in discussions with the consultant that did much of the AP-42 technical report 

and other studies (29 & 30) and with ORD’s wood stove contacts in NRMRL in NC. 

This also explains why there is not seasonal differences in ambient air levels where 

there is considerable residential wood burning. 

 

This leaves the question about wildfires. Very little data were found initially on metal 

emissions from wildfires. Two recent sources indicate that wildfires do not contribute the 

same level of Mn to the air as wood-fired boilers. Region 4 EPA partnered with ORD’s 

NRMRL to have the region’s lab run Mn analysis on samples that were taken, but not 

analyzed, for a study on particulate emission from burning of Foliar Fuels (31). The 

data from these sample analysis were compared to the fuel mass and air flow to 

determine actual mass emission rates for MN. These data indicate higher mass 

emissions on Mn from eastern species of trees, like Duke Forest (mixed) and 

Loblolly(414 and 546 ug/kg) and lower levels for western trees like Hemlock and 

Ponderosa (166 and 119 ug/kg). This study did not measure heat generated in these 

experiments. Therefore in order to get an approximation of emission factors an 

assumption of the residential fireplace was utilized to get emission rates in the AP 42 

format of lbs/MMBtu. Heat generated would have to be verified before claiming these 

as reasonable emission factors but, even with some uncertainty the conversion 
24 

indicates that emission factors are closer to wood stoves (1.3 to 6.3 X10-5 lb/MMBtu) 

than to wood-fired boilers. The results of this determination is given in table 11. 

Table 11 

Manganese Emissions from 

Burning of Foliar Fuels

Test Date Fuel Mass Mn Conc*. Mn Mass Emission Emission Factor** 

Kg ug/m3 ug/kg 10X-5 lb/MMBtu 

Duke Forest 3/8/00 8.7 0.15 414 4.786 

Hemlock 4/5/00 12.02 0.083 166 1.919 

Loblolly 2/11/00 5.8 0.12 546 6.312 

Palmetto 8/31/00 11.6 0.098 111 1.275 

Ponderosa 7/18/00 8.98 0.041 119 1.375 

* Analysis January 2004 by US EPA Region 4 Lab 

** Used conversion factor for wood stoves because no caloric measurement was done 

during original experiment. These data are estimate. 

 The October 2003 wild fires in California lead to considerable sampling by local air 

agencies. The results have been posted on the California Air Resources Board web site 

and summarized in a report, also on the web site. (35) While Mn was not a metal toxic 

of concern, there were a number of stations that measured Mn. The data indicate that 

ambient Mn levels did not increase much over historic levels and the levels at PM 2.5 

did not rise over 50 ng/m3. (highest recorded was 33 ng/m3) Considering the large 

increases of PM during these fires, it can be assumed that little of the Mn in the burning 

wood is getting into the increased PM levels. This low increase in Mn brings into 

question the assumptions in the Bureau of Mines “Manganese Material Flow Patterns 

(4). 
25 

Summary

Mn is by far the HAP metal emitted in the greatest amount from wood-fired boilers. It 

accounts for over 90% of the HAP metal emissions from burning wood. Most woodfired boilers will be covered by an upcoming MACT standard and will be required to 

provide particulate control. This will also reduce Mn emissions. The controls will reduce 

Mn emissions to levels experienced in wood-stoves and fireplaces. There is need to 

determine emission factors for Mn from wild fires and prescribed burns. 
26 

Manganese Emissions and Air Quality 

A final investigative question was going to look into how the emission factors were 

developed. This was addressed in the previous chapter, so the question was changed 

to one that tried to relate Mn emissions to ambient air levels. 

Approximately 180 ambient air monitoring sites in the US measure Mn. This data can 

be accessed via the AIRS-AQS data system. The units of measurement for Mn 

depend upon the State doing the measurement. There are three units that the Mn data 

are presented: (1) the Total Suspended Particulates (TSP) data with 80 sites; (2) some 

40 sites measuring PM10 and (3) 60 sites measuring PM2.5. These are the only 

monitoring sites available in the national system. 

South Carolina is the state with one of the most widespread monitoring systems in 

Region 4. They had 30 (all TSP) of the 180 monitoring sites in the 2000 data set. 

Therefore SC was taken as one of the focus areas to try to relate reported emissions of 

Mn in TRI with ambient levels from the many monitoring sites. Two sites in Georgetown 

SC had average ambient level of 0.1 ug/m3 which is double the EPA reference dose 

(RfD) of 0.05 ug/m3. Four monitoring sites in Georgetown all had recordable levels of 

Mn above the RfD. Only two had averages above the 0.1 level. These monitoring sites 

had frequent sampling with each one having over 60 observations. 

Reviewing a period from 1995 to 2001, TRI reports indicate only two significant air 

releases of Mn from the Georgetown SC area. These were Georgetown Steel and 

International Paper, Georgetown Mill. Both these facilities had Title V permits and both 

permits were reviewed to see how Mn was handled. The TRI data and ambient Mn 

levels for this period are shown in Table 12. The ambient data shows widespread 

elevations of Mn measured as TSP. The TRI data indicates that Georgetown Steel was 

the major reporter of emissions and that International Paper was only reporting air 

emissions of 170 lbs for most of the years. 

The TRI emissions do not seem to be accountable for the high ambient levels at the 

monitoring stations. One reading was 160 times the RfD for Mn. Since the acceptable 

ambient air concentration in SC is 25 ug/m3, this value probably did not raise concern. 

It is also of some concern that emission inventory data that was submitted to the state 

did not match the data reported to TRI. In 1999 the state reported that International 

Paper’s Mn emissions inventory was 14,300 lbs from their two wood-fired boilers. This 

was probably an error and their 2001 inventory reported 2,346 lbs., which is much 

closer to the TRI reported 1,100 lbs. This highlights the need for better coordination 

between emission data from different sources. One wonders why the TRI report is not 
27 

used as the emissions inventory data and why a separate number is generated for the 

permit. 

Table 12 

Comparison of TRI Air Releases and Ambient Mn levels in Georgetown SC 

TRI in lbs and Mn in ug/m3 (TSP)

Facility/Year 1995 1997 1998 1999 2000 2001

Air emission in Lbs 

Geo. Steel 5,900 2,061 1,102 1,319 1,513 2,291 

Int. Paper NR 170 170 180 170 1,100 

Monitoring Sta.

Ambient air conc in ug/m3 

06 Max 8.8 3.2 1.1 0.4 0.4 1.8 

06 Ave 0.3 0.2 0.1 0.1 0.1 0.1 

02 Max 0.6 1.4 0.4 0.2 0.2 0.4 

02 Ave 0.1 0.1 0.1 0.1 <.1 0.1 

07 Max <.1 0.2 0.3 <.1 0.3 0.1 

07 Ave <.1 <.1 <.1 <.1 <.1 <.1 

08 Max 0.1 1.2 0.6 0.4 0.6 0.3 

08 Ave <.1 0.1 0.1 0.1 0.1 0.1 

A review of their Title V permits revealed the following: 

International Paper (IP) Mill has two 592 MMBtu/hr boilers that have cyclone and ESP 

particulate controls. They are authorized to burn wood, coal and oil. Wood is reported 

to be the primary fuel. The permit had a PM limit of 0.1lb/MMBtu and had specific limits 

for six of the ten HAP metals as specified in State Regulations. They did not have limits 

for Mn. It is interesting to note that the sum of these six metal’s content in wood is 3.1 

mg/kg while the concentration of Mn is 33.6 mg/kg (see table 8). The permit contained 

a modeled emission rate for Mn, but this was very high (23.6lb/hr) and the State later 

said that it should have been a value maximum daily rate of 17 lbs/day (0.71 lb/hr). The 

amount of wood was required to be reported to the State but was marked confidential 

and is not releasable. Further information was obtained from the mill. They used a stack 
28 

emission test from a similar boiler at another IP mill, of 3.25X10-5 lb/MMBtu. This is 

comparable to NCASI data. The Boiler stacks are 83 meters high and should lead to 

wide dispersion of emissions. It was concluded that the current reporting of 1,100 lbs of 

emissions is closer to what the mill has been releasing. 

The Georgetown Steel Permit does not have any wood-fired boilers nor metal emission 

limits or monitoring requirements. This facility appears to be most closely related to 

Steel Foundries. AP42 does not have metal emission factors for this type of facility, only 

PM. The permit did have modeled emission rates for Mn and 3 other HAP metals. 

These were: 

Cadmium 0.0012 lb/hr 

Chromium VI 0.0104 lb/hr 

Manganese 0.1465 lb/hr 

Nickel 0.0007 lb/hr 

Manganese has a high emission rate compared to the other metals but if the plant 

operated continuously at this rate the annual emission would only be 1,283 lbs of Mn. 

The plant reported 2,291 lbs of Mn air emissions to TRI in 2001. 

The remaining monitoring sites in SC were reviewed and sites recording Mn levels had 

foundries or other metal processing facilities. While this was not part of the study it 

certainly is cause for more investigation. 

On the national level the two sites having the highest ambient levels of Mn were in 

Marrietta OH and E. Liverpool OH. Marietta OH is the home of the only 

Ferromanganese Alloy Plant in the US. It also has the highest reported TRI emissions 

with 431,600lbs being reported in 2000. E. Liverpool OH has the highest recorded Mn 

levels in the nation with average Mn levels at their two stations being 0.7 and 1.5 ug/m3, 

nearly an order of magnitude higher than Georgetown and 2 to 4 times higher than the 

0.4 ug/m3 levels the State of Ohio reported from their monitoring site in Marietta. 

In E. Liverpool there is no reported TRI releases and in the surrounding county there 

was only 600 lbs reported in 2000. E. Liverpool is also home to a Hazardous Waste 

Incinerator. Due to claims that the incinerator was the source of the high Mn levels, a 

major monitoring study was conducted to determine the cause (32). This study, with 

numerous monitoring stations, determined that the probably source was an unpermitted metal handler near the incinerator. It is surprising that the highest measured 

ambient levels in the nation are caused by a facility that is not being regulated. The 

report noted that they felt that the Mn measured was mostly larger than the fine level 

(2.5PM) and did not pose a high risk. Another Health Consultation (33) by ATSDR in 

Washington County (where Marietta is) also stated that there was not a serious problem 

because the levels never exceed the NOEL for Mn. This conclusion has been 

challenged because the ambient values greatly exceeded the RfC. 
29 

Summary

There is not a good correlation between ambient air concentrations of Mn and reported 

TRI releases. There appears to be a lack or coordination between reported emission 

inventory data and what is being reported in TRI reports. Mini-steel mills and metal 

foundries need further investigation to better estimate emissions of Mn from their 

operations. 

Manganese 

Summary and Conclusions

This study was conducted because of three concerns raised by a relative risk study 

done in Region 4. The concerns were 

1. Is Manganese a significant risk in the region as reported in the relative risk study? 

2. Is Manganese emitted from wood-fired boilers a significant risk? 

3. Is there a possible underreporting of Manganese from these boilers? 

These concerns led to a study that initially focused on wood-fired boilers and 

investigative questions on how much Manganese (Mn) is being sent to the boilers, 

what is happening in the boilers and how much is being emitted. This was 

expanded to determine what role to wood-stoves and wild fires play in Mn 

emissions. It was hoped that available studies would show the relationship that soil 

and ecosystems have in Mn levels in types of wood used in the wood-fired boilers 

and potentially determine a way to minimize emissions by type of wood used. 

It was determined that Mn does pose a risk to Region 4 because of its very low 

inhalation Reference dose (RfD). This value (0.05 ug/m3) is low because of a 

significant safety factor built into the value due to the lack of studies on sensitive 

groups that other hazardous metals have. Mn has not received the level of attention 

as other hazardous metals ( like Mercury) that have less stringent RfDs. As a result 

it is not limited and monitored in permits to the level that its low RfD would seem to 

require. Mn in high exposure is a neurotoxin but not a cancer causing substance. It 

is not considered bioaccumlative but its medical impacts (Manganism) are reported 

to continue and progress, after exposure is removed and the body levels are 

reduced. This seems worse than bioaccumlative metals, because it may not be 

easy to trace medical impacts back to an exposure. 
30 

Wood-fired boilers will not be a significant risk for Mn due to an upcoming Boiler 

MACT that will control particulates and therefore Mn emissions. Mn constitutes over 

90 percent of the Hazardous Air Pollutant (HAP) metal emissions from wood-fired 

boilers. Its concentration in wood is an order of magnitude higher than any of the 

other ten HAP metals. The Boiler MACT will require tight particulate controls and 

the post control MN emissions will be on the same order of magnitude as woodstoves that have emission estimates two orders of magnitude less that wood-fired 

boilers. Many current wood-fired boilers in the Paper sector already have 

Electrostatic Precipitators (ESP) that can remove particulates by up to 99%. 

There is considerable under reporting of TRI Mn emissions from facilities that have 

wood-fired boilers. Part of this is caused by the TRI limits before a facility is required 

to report. This limit of 25,000 lbs is considerably higher that for some other 

hazardous metals like mercury and lead where the limit is 10 lbs. The furniture 

industry uses wood-fired boilers and rarely report Mn emissions. Their controls were 

mostly mechanical and the removal efficiency was considerably less than those 

employing ESPs. Also a number of large boilers in the sugar cane industry employ 

waste cane (Bagasse). The cane also contains similar levels of Mn as wood and 

none of these facilities report TRI emissions. Based on a State of FL estimate of 

over 3.8 million tons of Bagasse burned and there are probably many facilities that 

are emitting significant amounts on Mn. 

While outside the scope of this study, the Mn emissions from mini-steel mills and 

foundries need to be evaluated to better estimate their air emissions. Disparities 

between ambient air Mn levels and reported TRI releases seems to point to ministeel mills and foundries as possible sources. 

Activities on the initial investigative questions led to mixed results. The first question 

was to determine how Mn levels in the wood vary by species and ecosystems. This 

question was not answered because, while there is considerable research on Mn by 

tree species, pH and available Mn in the soil, the data was reported mostly as Mn 

levels in leaves and needles. There is a need to relate the levels in leaves to bark 

and trunkwood concentrations. 

As to what happens to the Mn in the boiler, it appears than a majority of the Mn is 

emitted in the Fly Ash as a particulate. Particulate controls will control the Mn that is 

emitted. 

The third question was to review the emission factors. The emission factors 

published in EPA’s AP42 lumped a number of stack tests that included controlled 

and uncontrolled measurements. As a result the factor of 1.6E-3 lb/MMBtu 

understates the uncontrolled emission and overstates the controlled emissions that 

are in the E-5 lb/MMBtu range. 
31 

The expansion of study to effects on wood stoves indicated that these stoves are 

less efficient and most of the Mn remains in the bottom ash. The emission factors 

for wood stove and fireplaces are in same range as boilers with maximum controls. 

Emission factors for wildfires also appear to be less than boilers as indicated by the 

California Wildfire data and recent analyses from burning of foliar fuels. 

In summary it can be said that Manganese air emissions should receive much more 

attention than it is presently receiving. There is a definite need to increase medical 

research into sensitive groups to reduce the uncertainty factors that give Mn such a 

low threshold for concern. This is especially important as the decision to allow the 

gasoline additive MMT is being considered. 

Appendix 1 

References: Manganese and Wood-Fired Boilers

1. - US Environmental Protection Agency, 2002, US EPA Region 4 Relative Risk 

Initiative, Draft 2002 and not finalized. 

2. - Whitten, T., Wolfe, R., 2002, Memo - Relative Risk Initiative - Manganese 

Compounds in Wood Waste Boilers - Example - Masonite” Internal Memo MS Dept 

of Environmental Quality, December 17, 2002 

3. - National Research Council Committee on Biologic Effects of Atmospheric 

Pollutants, 1973, Manganese, National Academy of Sciences, ISBN 030902143X 

4. - Jones, T., 1994. Manganese Material Flow Patterns, Bureau of Mines 

Information Circular 9399, Dept of Interior. 

5. - US Geological Survey, 2003, Manganese Statistics and Information, 

http://minerals.usgs.gov/minerals/pubs/commodity/manganese/index.html 

6. - Hudnell, K., Mergler, D., 1999, Manganese: Essential Element and Neurotoxin, 

Occupational Medicine Secrets, 1999 Haney & Belfus Inc. 
32 

7 - Centers for Disease Control and Prevention, 2003, Candidate Chemicals for 

Possible Inclusion in Future Releases of the National Report on Human Exposure to 

Environmental Chemicals, Federal Register Vol. 68 No. 189/ Tuesday September 

30, 2003. 

8. - Williams-Johnson, M., Altshuler, K., Rhodes, S., 2000. Toxicological Profile for 

Manganese, Agency for Toxic Substances and Disease Registry, CDC 

9. - Davis, M., and 10 others, 1994, “Reevaluation of Inhalation Health Risks 

Associated with Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Gasoline, 

US EPA ORD, EPA 600/R-94/062 

10. - Roels, H., Ghyselen, P., Burchet, J., 1992, Assessment of the Permissible 

Exposure Level to Manganese in Workers Exposed to Manganese Dioxide, 

Neurotoxicology, 20; 255-272 1992 

11. - Hudnell, K., 1999, Effects from Environmental Mn Exposures: A Review of the 

Envidence from Non-Occupational Exposure Studies, Neuro Toxicology 20(2-3):379-

398, 1999 

12. - Glenn, W., The Heavy Metal Blues, 2001, OH&S Canada, Apr/May 2001, Vol 

17, Iss. 3 pg.22 

13. - Masters, R., Hone, B., Doshi, A., Environmental Pollution Neurotoxicity, and 

Criminal Violence, 1997, In Rose, J (ed): Environmental Toxicology, London, 

Gordon, and Breach, 1997 

14 - Huang, C., Chu, N., Lu, C., et al. 1998, Long-term progression in chronic 

manganism. Ten years of follow-up, Neurology 50:698-700, 1998 

15. - Zekri, M., Obreza, T., 2003, Plant Nutrients for Citrus Trees, SL 200 Univ of 

Florida Extension, http://edis.ifas.ufl.edu , January 2003 

16. - ____ 2001, Manganese in Soils, Fact Sheet from Incitec Fertilizers, 

Queensland, Australia 

17. - _______ 2001, Soil and Plant Nutrition- Manganese, Tree Fruit Research & 

Extension Center, Washington State University 

18. - Sadowski, A., et al, 1980, Effects of Different Levels of Manganese and Boron 

upon the Nutrient Status and the Incidence of Internal Bark Necrosis in Apple Trees, 

ISHA, 92:378-378, 1980 
33 

19. - Tracy, J., 1991, Manganese Toxicity in Avocado, California Avocado Society 

1991 Yearbook 75:147-158, 1991 

20.- Gower, S., 2001. Manganese Deficiency of Fraser Fir, Michigan State University 

Extension. 

21.- _______ ____ Plant Analysis and Fertilizer Recommendations- Walnut, K Ag 

Labs, http://www.kaglab.com/walnut/plnanly.htm

22.- Hiltbrunner, E., Fluckiger, W., 1995, Manganese deficiency of silver fir trees 

(Abies alba) at a reforested site in the Jura mountains, Switzerland: aspects of 

cause and effect, Tree Physiology 16, 963-975 1996 

23. - American Furniture Manufacturer’s Association, 2003, Manganese Evaluation 

in Wood Fuel, Report submitted to EPA Docket Center, October 17, 2003, Docket ID 

No. OAR-2002-0058. 

24. - Cooper, C., 1999, Background Information on the Sugarcane Industry and 

Summary of Stack Test Results from Bagasse-Fired Boilers in Florida and 

Louisiana, University of Central Florida 

25. - Wessel, R., Jorgensen, K., 2001, Combustion Modeling of Kraft Recovery 

Boilers and Stoker-fired Power Boilers, McDermott Technology Inc. MTI 01-10, 2001 

26. - US Environmental Protection Agency, 1995, Compilation of Air Pollutant 

Emission Factors, AP -42, Fifth Edition, Volume 1: Stationary Point and Area 

Sources, Chapters 1.6, 1.9, and 13.1 (Wood Residue Combustion, Residential 

Fireplaces, and Wildfires and Prescribed Burning), January 1995, 

http://www.epa.gov/ttn/chief/ap42/ 

27. - Eastern Research Group, 2001, Background Document Report on Revisions to 

5th Edition AP 42 Section 1.6, US EPA Contract No. 68-D2-0160, July 2001 

28.- Hassler, C., Anderson, B., Hutchinson, V., 1998 Overview of Wood-Fired Boiler 

Use in West Virginia, Appalachian Hardwood Center Fact Sheet 16, West Virginia 

University 

29.- Houck, J., Tiegs, P., 1998, Residential Wood Combustion Technology Review - 

Volume 1, EPA-600/R-98-174a, December 1998 

30. - Houck, J., Scott, A., Sorenson, J., Davis, B., 2000, Comparison of Air 

Emissions between Cordwood and Wax-Sawdust Firelogs Burned in Residential 
34 

Fireplaces, Proceedings of: AWMA and PNIS International Specialty Conference. 

April 2002 

31. - Hays, M., Geron, C., Linna, K., Smith, D., Schauer, J., 2002, Speciation of GasPhase and Fire Particle Emissions from Burning of Foliar Fuels, Environmental 

Science & Technology: Vol 36 NO. 11: 2281-2295 

32. - Singhvi, Raj, A Final Report on Environmental Monitoring in the Vicinity of 

VonRoll WTI Incinerator Facility, May 2003, OSWER, USEPA, www.epaosc.org/WTI

33. Colledge, M., Freed, J., 2003, Health Consultation Washington County Air 

Quality, Marietta, Ohio, ASTDR dated August 11, 2003 

34. - Kaiser, J., 2003, Manganese: A High-Octane Dispute, Science Vol 300, 

9May2003, www.sciencemag.org 

35 – CA Air Resources Board, 2003, Air Quality and Wildland Fires of Southern 

California, October 2003, CA Air Resources Board, December 2003, 

www.arb.ca.gov 

Additional References

36. - Zekri, M., Obreza, T., 2003. Plant Nutrients for Citrus Trees, SL 200 of Florida 

Cooperative Extension Service. 

37. - Muse, J., Mitchell, C., 1995, Paper Mill Boiler Ash and Lime By-Products as 

Soil Liming Materials, Agronomy Journal Vol 87:432-438 1995 

38. - Liard, A., Lessard, R., Desilets, L., 1999, Product from residue: standard setting 

for alkaline mill residues in Quebec, Pulp Paper Can. 100 (5): T135-137 (May 1999) 

39. - Risse, M., Gaskin, J., 2002 Best Management Practices for Wood Ash as 

Agricultural Soil Amendment, Cooperative Extension Service Bulletin 1142, 

University of Georgia. 

40. - Hedberg, E., Kristensson, A., Ohlsson, M., Johnansson, C., Johansson, P., 

Swietlicki, E., Vesely, V., Wideqvist, U., Westerholm, R., 2002, Chemical and 

Physical Characterization of Emissions from Birch Wood Combustion in a Wood 

Stove, Atmospheric Environment 36 (2002) 4823-4837 

41. - Omni Environmental Services, 1989, Determination of Particle Size Distribution 

and Chemical Composition of Particulate Matter from Selected Sources in California, 

California State Air Resources Board PB89-232805 
35 

42. - Hubbard, A., 1995, Hazardous Air Emissions Potential from a Wood-Fired 

Furnace, Combust.Sci and Tech, 1995, Vol.108, pp 297-309 

43. - Mamuro, T., Mizohata, A., Kubota, T., 1979, Elemental Compositions of 

Suspended Particles Released from Various Boilers, Annual Report of the Radiation 

Center of Osaka Prefecture, Vol 20 (1979) 

44. - ________, 1997, Toxic Air Contaminant Identification List - Manganese, 

California Air Resources Board, September 1997 p 620-623 

45. - US Environmental Protection Agency, 2002, Tri-State Geographic Initiative, 

Greenup Industrial Cluster Air Monitoring and Air Modeling Risk Assessments, 

USEPA Contract 68-W7-0045, June 2002. 

46. - Eastern Research Group, 2001, Residential Wood Combustion, Emission 

Inventory Improvement Program, Volume III, Chapter 2, January 2001, 

http://www.epa.gov/ttn/chief/eiip/techreport/ 

47. - National Institute of Standards and Technology and Colorado School of Mines, 

2002, Properties of Lead-Free Solders, February 2002, http://www.boulder.nist.gov/

48. - US Environmental Protection Agency, 1999, Compendium of Methods for 

Inorganic Air Pollutants- Chapter IO-3, June 1999, 

http://www.epa.gov/ttn/amtic/inorg.html

49. - Sullivan, R., 1969, Preliminary Air Pollution Survey of Manganese and its 

Compounds , Prepared under contract # PH 22-68-25 for Public Health Service, 

October 1969 

Appendix B 

Persons contracted during Study of Manganese from Wood-Fired 

Boilers

 

Name Organization 

 Telephone/email

Dave Tingey WED, NHEERL 541-754-4621 

William Hogsett WED, NHEERL 541-754-4632 
36 

Allison Stock CDC Ags2@cdc.gov

Alden Henderson CDC 404 498-1351 akh0@cdc.gov

Stephanie Davis CDC epidemiologist 404 498-0603

sgd8@cd

c.gov

Ken Hudnell RTP, NHEERL 919 541-7866 

hudnell.ken@epa.gov

Allison Humphris Region 4 404 562-9122 

Jim Little Region 4 404 562-9118 

John Ackermann Region 4 404 562-9063 

Beth Antley Region 4 404 562-8454 

Jackie Lewis Region 4 404 562-9061 

Danny France Region 4 SESD 706 355-8738 

Mike Wasko SESD - metal 706 355-8821 

Jenny Scifers SESD - Inorganic 706 355-8812 

John Calcagni WRRC 919 715-6534 

Richard Engler OPPTS 202 564-8587 

Julia Gaskin Univ GA 706 542-1401 

Larry Morris Univ GA 706 542-2532 

lmorris@arches.uga.edu 

Ashak Jain NCASI- FL 352 331-1745 

a_jain@src-NCASI.org 

Arun Someshwar NCASI- FL 352 331-1745 ext 226 

Larry LaFlure NCASI- COR 541 752-8801 

Jim Pinkerton NCASI - RTP 919 941-6406 

Jpinkerton@NCASI.org 

Chris Swab OR DEQ 503 229-5661 

Roy Huntley OAQPS (inventory) 919 541-1060 

Bob Whalen OAQPS (combustion) 919 541-1045 

Jim Eddinger OAQPS (boilers) 919 541-5426 

Joann Rice OAQPS (E.Liverpool) 919 541-3372 

Nealson Watkins OAQPS (E.Liverpool) 919 541-5522 

Dan Hopkins Region 5(GL) 312 886-5994 

Thelma TRI Region 5 312 886-6219 

Gary Victorine HW Incin. R5 312 886-1479 
37 

Raj Singhvi Edison (E.Liverpool) 732 321-6761 

Ying Hsu was CA ARB 916 445-4292 

now Pechan&Assoc. 530 295-2995 

yhsu@pechan.com 

Joe Behar ORD- LV 702 798-2361 

John Kinsey woodstove std NRMRL-RTP 919 541-4121 

Dean Smith (Pulp Mill Std) NRMRL-RTP 919 541-2708 

Michael Hays (open burning NRMRL-RTP 919 541-3984 

Bill Perdue bperdue@afma4u.org Am Furn Manf Ind. 336 884-5000 

www.AFMA4U.org 

Jim Houck houck@omni-test.com OMNI Env. Ser 503 643-3788 

Ross DuBose SC Air Modeling 803 898-4123 

Bob Betterton betterrj@dhec.sc.gov SC Emission Inv 803 898-4292 

Allyson Bristow (emissions) IP Georgetown 843 545-2291 

Karsten Bauman kb@eas.gatech.edu GA Tech 404 385-0583 

Tim Hunt Air Director Am.Forest & Paper 202 463-2588 

Cindy Dewulf OH TRI prog 614 644-3606 

Mike Kelley OH P2 Prog 614 644-2930 

Paul Koval paul.koval@epa.state.oh.us OH Air 614 644-3615 (or 14) 

Lisa Corathers( Thomas Jones ret.) USGS MN Spec. 703 648-4973 

Jeff Koener FL Air 850 921-9536 

Derrick Brown (Canton NC) Blue Ridge Paper 828 646-2318 

Darryl Wite Blue Ridge Paper 828 646-6814 

John Kennedy Region 9 Air 415 947-4129 

Catherine Brown Region 9 Air 415 947-4137