Toxic Metals: Emissions, Deposition, Health Effects, Controls 1-31-2001
& the relation to incinerators, coal plants, acid rain
This paper is primarily an annotated bibliography summarizing articles, books, documents and newspaper clippings relating to the above aspects of toxic metals and their impact on health and the environment. A primary source of the information is the reading files or summary articles of the State Pollution Control Agencies of Florida, Minnesota, and Wisconsin. The primary effort made to verify accuracy of information referenced was general screening, cross comparisons, and feedback from other technical sources; and the articles are referenced and available for more detailed analysis
I. Health Effects of Toxic Metals (mercury, lead, cadmium, chromium, etc.)
II. Mercury in Fish and the Food Chain of Lakes and Streams and Bays
III. Effect of Toxic Metals on Forests and Plant Ecosystems
IV. Sources of Mercury Emissions and Mercury Content of Fuels
V. Emissions of Other Toxic Metals from Human Activities
VI. The Relation of Acidity and Acid Rain to Toxic Metal Impacts on Aquatic Systems, Fish, the Food Chain, and Health2
VII. European Experience with Mercury Emissions
VIII. Experience with Emissions Control Equipment for Toxic Metals and
Mercury Reduction Options
IX. Toxic Metals in Flue Ash and Bottom Ash
X. Heavy Metals and Drinking Water
XI. Toxic Metals from Sewer Plants and Urban Runoff
Summary
Toxic metals(mercury,lead,cadmium,aluminum,etc.) appear to be the number one environmental health threat in Florida currently and appear to be seriously affecting thousands of Floridians, especially children and older people. Toxic metals have been documented to be neurotoxic, as well as reproductive and developmental toxins. Over 60 % of Florida lakes and rivers tested last year by the Game and Fresh Water Fish Commission had dangerous levels of mercury in the fish and food chain(33,33.3) and over 20% of all U.S. lakes have similar warnings(64). High levels of mercury are also being found in other wildlife such as frogs, turtles, raccoons, alligators, etc. with many birds and an endangered Florida panther being killed by high levels of mercury. Florida is one of a growing list of at least 40 states and 4 Canadian provinces(24.5,64) with bans or limits on eating fish from thousands of lakes or rivers with dangerously high levels of mercury in fish. Europe has similar experience. Dangerous levels of mercury have also been found in shark, tuna, sea trout, sailcat, mackerel, bluefish, etc., as well as toxic metals in shellfish(16.5). Over 90% of the health risk to the public(and animals) from toxic metals such as mercury(as well as from dioxin) has been found to be related to such toxics that are bioaccumulating in the food chain. Mercury, cadmium, and lead have been found to be estrogenic chemicals that disrupt the endocrine/reproductive/hormonal systems of animals at low levels of exposure, with serious adverse seen on animals and humans
(14.5,14.7).
Most of the mercury in Florida lakes and soils is from atmospheric deposition, and the main sources of air emissions are municipal incinerators, medical waste incinerators, and coal combustion. Dental amalgam which is the largest source of mercury in sewers is also a significant source in rivers, lakes, and fish(14.9). A Dept. of Environmental Protection report said that past tests indicate that Florida incinerators and power plants were emitting approx. 6 tons and 3.4 tons per year of mercury emissions to the Florida environment. Such facilities also emit large volumes of lead, cadmium, and other toxics. Of the approx. 6 tons of mercury generated in Fla. by coal plants, approx. 50% appear to be as air emissions with the rest going into the ash. There appear to be only minor natural sources of mercury in Florida, other than recycling of previously deposited mercury by plants, soils, etc. which is significant in some areas. Coal plants from other states and oil combustion in Florida together appear to deposit almost as much mercury as Fla. coal plants, but Florida plants also affect other states.
Studies in Wisconsin and Canada indicated only one gram of mercury per year deposited in an average sized lake(25 acres) is sufficient to contaminate fish and the food chain at dangerous levels requiring a fish consumption ban or limitation(18). The amount of mercury emissions each year by incinerators and coal plants(36 grams/square mile) are enough to uniformly deposit 16 grams and 20 grams per square mile respectively, for each of the 53,800 square miles of Florida. These levels each appear to be well above the level of deposition required to cause dangerous levels of mercury in fish throughout the state(2.5 gm/sm), especially in lakes with low acidity or low alkalinity like many of Florida's lakes(1.5,1.6). The average level of deposition into Minnesota lakes with mercury health warnings was 13 micrograms per square meter(34 grams per square mile) and for Florida
the average deposition throughout Florida in 2001 was 17.6 micrograms per square meter(1.5b).
The levels of the toxic metals mercury, lead, cadmium, copper, selenium, arsenic, zinc, and silver are increasing cumulatively in the environment due to atmospheric emissions from human activity. Mercury levels in Minnesota, Wisconsin, Canada, and Sweden were found to be increasing in sediments, soils, and fish at rates between 2% and 5% per year. Levels in Florida have also been found to be increasing by a Univ. of Florida study. Toxic metals were found in water body sediments sampled at levels exceeding the FDEP toxics criteria in 30% of "reaches" sampled for mercury, 15% for cadmium, 20% for copper, 15% for lead, etc. The higher rates were in areas with major emission sources and in recent years. At this rate of increase, levels double in as little as 10 years. Levels of toxic metals in soils and plants in industrial areas were found to be doubling in many cases every 3 to 10 years. Mercury, lead, cadmium, and manganese are now being deposited in some areas at levels toxic to humans as well as other animals and plants. The other toxic metals previously listed are being deposited at levels toxic to plants or other organisms.
High levels of other toxic metals have also been found in drinking water, surface water, sediments, and the food chain throughout Florida. Toxic metal air emissions have been suggested to be a factor in high lung cancer rates of some areas of North Florida. Toxic metals have been documented to cause large numbers of learning disabilities, neurological disorders, cardiovascular disease, hormonal problem, reproductive problems, and kidney disease(5.5,1.8,14.7,27.7), as well as being major factors in the promotion of cancer and birth defects(7.5). Approximately 250,000 U.S. children are born each year with birth defects diagnosed at or shortly after birth. Birth defects are the leading cause of infant mortality in the United States. Congenital anomalies, sudden infant death syndrome, and premature birth combined account for more than 50% of all infant mortality(62).
According to Federal studies, thousands of children appear to have their learning ability and health permanently adversely affected in Florida each year. Because of this, all school systems were ordered by EPA to have their water systems tested. Over 20% of Leon county school water fountains were found to have dangerous levels of lead in the water, and higher levels were found in some other counties. An EPA drinking water survey found that the average lead level in drinking water in many areas of Florida was above the EPA drinking water standard of 20 parts per billion, a level shown high enough to cause significant health effects. A large proportion of drinking water in some areas of Florida appears to have dangerous levels of lead from pipes, solder joints, brass fixtures, or water fountains.
The increase in toxic metals in water and the food chain has been shown to be related to increased acidity of drinking water and surface water. Additional sources of large amounts of metals in bay, lake, or river sediments are sewer or industrial outfalls and urban runoff.
I. Health Effects of Toxic Metals (mercury,lead, cadmium, & chromium, copper, nickel, etc.)
1. The levels of the toxic metals mercury, lead, cadmium, copper, selenium, arsenic, zinc, and nickel are increasing cumulatively in the environment due to atmospheric emissions from human activities(1.9,2,2.1,16.3,1). Mercury, lead, cadmium, nickel, and manganese are now being deposited through atmospheric emissions in many areas at levels toxic to humans, as well as to other animals and plants. The average annual percent increase in emissions of these metals has ranged from 1.5% to 5% (2), with accumulation in soils and plants in some industrial areas of the U.S. and Europe doubling in between 3 to 10 years and in many cases reaching levels known to cause critical health problems. Studies of human bones have found a 500 fold increase in the levels of toxic metals such as lead currently as opposed to preindustrial times. A large British study(15.1) found a statistically highly significant, age related increase in the levels of toxic metals(aluminum,mercury,arsenic,cadmium, lead) accumulating in the British population, as measured in hair, blood, and sweat samples. Increasing body burdens of these toxic metals have been found to be widely accumulating in industrial country populations throughout life, with increasingly significant adverse health effects due to this accumulation as populations age. Brain function and kidney function are being especially adversely affected in large segments of the population of industrial countries over 40 years of age. There has been a large increase in depression, impulsivity, and dementia in the U.S. since 1945(5.5,15.1) and toxic metals such as lead, mercury, and cadmium have been found to adversely affect levels of brain neurotransmitters resulting in these conditions(3.1,9.3,9.7,15.1,5.5,1.8).
2. The U.S. Center for Disease Control ranks toxic metals as the number one environmental health threat to children, adversely affecting millions of children in the U.S. each year and thousands in Florida(1.7,2.4,1). According to an EPA/ATSDR assessment, the toxic metals lead, mercury, and arsenic are the top 3 toxics having the most adverse health effects on the public based on toxicity and current exposure levels in the U.S.(1,9.3), with cadmium, chromium and nickel also highly listed. A National Academy of Sciences Report(65) found that 50% of U.S. pregnancies result in birth defects or neurological conditions or other chronic developmental problems. Researchers have documented that the majority of these are due to toxic exposures(5.5,7.5,14,5,14.7,1.8,etc.) According to studies reviewed, over 16% of all children in the U.S. have had their learning ability(ADHD, dyslexia,autism,learning disabilities) significantly adversely affected by toxic metals such as lead, mercury,and cadmium; and over 60% of children in some urban areas have been adversely affected(1.7,5.5,6,9,15.3,47-50).
The toxic metals have been documented to be reproductive and developmental toxins, causing birth defects and damaging fetal development, as well as neurological effects, developmental delays, learning disabilities, and behavioral abnormalities in many otherwise normal-appearing children(5.5,7.5,9.1,9.3,9.7,19.2,47-50,1.8). Other neurological disorders are also increasing, partly due to exposure of millions of American workers to neurotoxic substances such as toxic metals and pesticides(15.7).
3. Lead poisoning is the most prevalent environmental disease in the U.S along with mercury toxicity. According to an EPA survey, over 10% of all Americans and over 20% of all black children under 2 carry unsafe levels of lead in their bodies(over 10 mcg/dl) (9). In an urban east coast area, almost half of children tested in 1998 had lead levels exceeding the federal blood levels guideline(41.5).
Lead is a leading cause of birth defects, cardiovascular disease, hypertension, neurological disease, kidney disease, learning disability, retardation, tooth cavities,etc.(2‑3,5.5,8‑9,15.1,28,41,49,50). An increased lead burden of 5 ug/L in the blood corresponded to an increase in cavities of 80%(41). Lead also has been shown to depress the immune system and increase cancer rates(1.3, 9). Federal studies indicate that exposure to lead in the environment reduces the IQ of hundreds of thousands of U.S. children each year and causes pregnancy complications to over 500,000 U.S. women each year(2.3, 2.4). Children aged 7 to 11 with high levels of lead in their bones were found to exhibit much higher levels of attention problems, aggressive/violent behavior, and delinquency than those with lower levels(5.5).
Drinking water is a major source of lead in humans according to EPA. Other major sources are lead in old paint, lead solder in cans, lead in soils from previous gasoline exhaust, lead emissions from incinerators, and lead in food chain(1.2). EPA studies show that hundreds of thousands of school children are being exposed to dangerous levels of lead in drinking water from fountains at U.S. schools(2.3, 2.4). Levels from gasoline exhaust and cans have decreased in the U.S., but are still extremely high in some other countries.
Studies have confirmed lead in drinking water is a major problem in Florida(2.4). Millions of people are exposed to dangerous levels of lead and other toxic metals through home drinking water which has absorbed lead or other toxic metals from pipes, solder joints,brass fixtures, etc.
according to EPA(2.4,2.6). An EPA drinking water survey (2.4, 2.8) found that the average lead level in drinking water in many areas of Florida was above the EPA drinking water standard of 15 parts per billion(parts per billion(ppb)., a level high enough to cause significant health effects. Counties with a significant number of homes above the EPA standard were Escambia, Brevard, Volusia, Lee, Broward, and Dade.
4. Lead has been shown to be one of the most potent promoters of cancer and birth defects(2.2, 9). In a Swiss study of residents living on a busy roadside, a group of residents having free blood lead removed by calcium EDTA treatment was compared to a control group that did not. 17% of those not having lead removed died of cancer while only 1.7% of those having lead removed died of cancer(2.2).
A Boston area study found lead to be a potent promoter of birth defects. The study suggest that as much as 46% of all birth defects in the area were facilitated by or related to level of lead in the blood of the fetus. Low levels of lead were found to promote birth defects, with a blood lead level of 6.3 micrograms per deciliter(mcg/dl) being associated with an 87% increase of birth defects. A blood lead level of 15 mcg/dl had a 137% higher risk of birth defects relative to the group with less than 0.7 mcg/dl (9). (1 mcg/dl=10ppb)
Cadmium has also been found to be a promoter of sperm abnormalities, birth defects, uterine fibroids, infertility, spontaneous abortions(1.5,3,42,46,51), lung and brain cancer(40,52,55), and peripheral neuropathy(56).
5. Studies reviewed suggest that exposure to toxic metals may account for as least 23% of learning disabilities, 20% of all strokes and heart attacks, and in some areas be a factor in over 40% of all birth defects. Primary exposure to lead is from drinking water,auto and industrial emissions, and lead in paint. Cadmium,mercury chromium, arsenic, silver, copper, and aluminum are other metals to which Floridians are commonly exposed in drinking water or the food system(3).
6. Researchers at the U.S. Public Health Service and at Harvard Univ. have found that blood pressure in men increases significantly at 20 mcg/dl blood level compared to 10 mcg/dl (4). Another study found a linear relation between elevated blood lead and blood pressure down to 7 mcg/dl (4.5). Other studies have also found both lead and cadmium to be significant causes of high blood pressure, heart attacks, and stroke(4.7 & 3).
7. A study of school children in Maryland found that both lead and cadmium had significant impacts on learning ability. The group of children labeled gifted by teachers all had low levels of blood lead, while all children with blood lead levels of 50 ppm or more were in the very low achiever group. There was a very high correlation between blood lead level and achievement group(5). These results were also confirmed by a recent medical studies published in The New England Journal of Medicine(6.5) and other studies(2.7,6,15.1,15.3,47-50,5.5).
8. Exposure to the 5 heavy metals tested for in a study of school children accounted for 23% of the variation in test scores for reading, spelling and visual motor skills(6,15.3). A Canadian study found that blood levels of five metals were able to predict with a 98% accuracy which children were learning disabled(7). Animals exposes to a very low-dose mixture of six metals displayed severe growth retardation and other abnormalities in the exposed fetuses, indicating a synergistic effect of the metals in combination(10.8,19.8).
9. Medical studies have shown that low levels of lead in the blood of infants(as low as 6.5 mcg/dl) have significant effects on mental development and learning ability. An average level of 14.6 mcg/dl had serious impacts(8, 8.5, 8.7, 2.7,5.5).
10. There is a significant correlation between maternal blood lead level with birth weight and early learning ability. Adverse effects were found as low as 8 micrograms per deciliter(9 & 9.5 & 2.7).
11. A study of 14 to 19 year olds found that the amount of lead in the blood was the most important factor in hearing threshold levels in children. Levels as low as 10 micrograms per deciliter had a significant effect and there was no threshold level(10). The lead blood level also was found to be a significant factor in the age at which a child first sat up, walked, and spoke(10); as well as being related to reductions in height of children(4.5).
12. A review of studies involving cadmium suggest cadmium is as effective as lead at causing high blood pressure and heart disease. Likewise cadmium has been found to produce learning disabilities and mental retardation in children much like lead, as well as causing kidney damage(54,57.5),sperm abnormalities, and sterility in men(2,3,6,1.2,15.1,15.3,47-51,54). One study(53) found a significant correlation between hair cadmium level and sporadic ALS(53). Cadmium has also been found to bioaccumulate in the food chain and to be reaching dangerous levels in shellfish and animals(28,3.7,1.2). Cadmium has been found to be widely distributed in sediments of Florida's bays and estuaries(3.3), and is acutely toxic to marine life at sediment levels as low as 6.9 parts per trillion(parts per trillion(ppt)(3.5). Cadmium also appears to be an endocrine system disrupter and to cause other biological harm at lower levels (14.5). The FDEP NOEL(no observed effects level) is 1 parts per million(ppm). The FDEP PEL(probable effects level-lower limit of range associated with adverse biological effects) for cadmium is 7.5 ppm. Cadmium levels is sediments of 4 harbor areas in the Indian River Lagoon were found to be .6 to .8 ppm, with much higher levels in several urban coastal areas(3.7,3.3). The U.S.EPA(38) toxics criterion for cadmium in seafood used in coastal monitoring programs is 0.5 ppm. The FDEP NOEL for lead in sediments is 21 ppm and the PEL is 160 ppm, which are also exceeded in some areas of Florida. The EPA toxics contaminant criteria for lead in seafood is 0.5 ppm. The FDEP NOEL for copper of 28 ppm and for chromium of 33 ppm are also exceeded in many areas of Florida. The PEL for copper and chromium respectively are 170 ppm and 240 ppm(3.5). The EPA contaminant criteria for copper in seafood is 15 ppm and for chromium is 1ppm. The EPA criteria for zinc is 60 ppm.
13. European studies have found a correlation between long‑term air exposure to cadmium levels in industrialized urban areas with lowered kidney function (12,15.1). Hundreds of thousands of people suffer from serious kidney dysfunction due to cadmium(2,15.1). As a result of research carried out by the Danish National Agency of Environmental Protection, the EEC Council of Environmental Ministers has concluded that present environmental levels of cadmium are potentially harmful, with harmful levels of cadmium accumulating in the lungs, bone tissue, brain, and kidneys(44). Cadmium(and mercury) has been found to be a major cause of neurological dysfunction such as Alzheimer's disease and other dementia(15.1, 5.5,9.7). Cadmium has also been shown to be toxic to the testes and sperm at fairly low levels and to damage the placenta, which can cause damage or death to the fetus(9.8,46).
Significant levels of cadmium have been found in the German food system. Sweden has instituted a ban on many uses of cadmium such as for paint pigment, and other European countries are considering such bans(3). Japanese studies indicate the lungs, gastrointestinal system, and kidneys are especially susceptible to cadmium poisoning. A daily intake of 200 ug of cadmium was found to significantly increase kidney damage in humans. Normal intake in diet is 50 to 80 ug(13). Cadmium from combustion emissions is also accumulating in coastal estuaries and inland water body sediments, and is widespread in shellfish and other organisms. Cadmium is toxic at relatively low levels and has serious impacts on the organisms in water bodies that accumulate cadmium(4.3,1.2).
14. The heavy metals(lead,mercury,cadmium) tend to concentrate in the air and in the food chain, facilitating metal poisoning which is the most widespread environmental disorder in the U.S. These heavy metals have also been found to be endocrine systems disrupting chemicals having effects on the endocrine and reproductive systems similar to the organochlorine chemicals(14.3,14.5,5.5). Estrogenic chemicals like mercury have been found in Florida wildlife at levels that feminized males to the extent of not being able to reproduce, and also had adverse effects on the female reproductive systems. Chromium is also on the EPA Special Health Hazard Substance List because it is "a cancer-causing agent and a mutagen". Lungs & throat are especially affected. (11.7)
15. "The neurotoxicity of alkylmetals such as mercury represents a major environmental health problem which should be of international concern."(1.7-1.9,9.3,9.7,16.5,1,63) Mercury is found in 3 different forms: elemental mercury vapor, inorganic mercury compounds, and organic mercury. The organic methyl mercury form bioaccumulates to very high levels in the food chain and readily crosses the brain membrane where it can do severe irreversible damage (11,28,9.3,9.7,15.1,16.5, 1.2). Fish and seafood are common sources of mercury in people, but other sources of elemental mercury also result in methyl mercury since it is commonly methylated by bacteria and yeasts in the mouth and intestines to methyl mercury(1.8). The number one source of metallic/inorganic mercury is from amalgam dental fillings(1.8,1.7) but this is also the largest source of methyl mercury for many people. Exposure levels for those with amalgam fillings commonly exceed Gov’t health guidelines(1.8,1.7,1.2,), which is 0.2 ug/M3 for mercury vapor. Thousands also get harmful exposure levels from occupational exposure such as working in dental offices(1.8). Inhaled metallic mercury vapor is able to diffuse much more extensively into blood cells and various tissues than inorganic mercury (22.8,1.8). Approx. 70% of methyl mercury in consumed fish or food is absorbed and retained in the body. The Gov’t health guideline for organic mercury is 0.1 ug Hg /kg body weight(1.7). Mercury has been extensively documented to have serious adverse health effects including brain and neurological damage, kidney failure, birth defects, learning disabilities, depression, impulsivity, etc. (1.2,1.8,3,5.5,6,9.7,14,14.7,15.1,15.3,16.5,17,19.2,63). Mercury has been found to adversely affect the brain's neurotransmitter uptake of serotonin, dopamine, acetylcholine, and norepinephrine which control the body's neurologic functions(1.8,14.7). Low serotonin levels have been shown to result in depression, anger, anxiety, aggression, violence, insomnia, obesity, sexual deviance, and other impulse disorders.
Epidemiological studies have found that human embryos are highly susceptible to brain damage from prenatal exposure to mercury(7.5,9.7,5.5,1.8,63). Levels in the fetus are usually higher than the blood level of the mother, and significant levels of mercury are often found in breast milk(7.5,9.2,45,1.8). Normal levels in breast milk range up to 1.0 ug/L Cd, 5 ug/L Pb, and 1.7 ug/L Hg, but levels above this are commonly found. ATSDR staff recommend screening levels for dangerous effects of 5 ug/l Cd, 20 ug/L Pb, and 3.5 ug/L Hg(45). Mercury has also been documented to cause cellular DNA damage and cancer in animal studies(19.4). Mercury has been documented to be causing serious harm to birds, animals, and humans (2,14.5,14.7,16.5,17.4,18,19.4, 28,28.5,33,1.8). Native Americans eating fish on a regular basis have been found to have serious health effects. Over 100 Japanese died and many more were seriously affected neurologically where infants suffered mental retardation, severe cerebral palsy, incoordination, weakness, seizures, vision loss, etc. after eating fish contaminated with 10 to 20 parts per million(ppm) methyl mercury(about 1000 micrograms per 1/4 pound serving)(9.4,18). A large cohort study of occupationally exposed women found an increased risk of spontaneous abortion and other pregnancy complications(9.6,7.5).
The World Health Organization maximum safe level for human ingestion was based mostly on acute toxicity and is 30 micrograms per day. The ATSDR/EPA MRL amounts to between 3 to 7 micrograms per day(9.3,1.7,1.8). The average U.S. average human intake for those with amalgam fillings is over 10 micrograms per day, but most with several fillings have excretion levels of about 30 micrograms per day, and a study of a group in New York eating more than the average amount of fish found many ingesting over 40 micrograms per day. The Minnesota Dept. of Health recommends limiting the intake of mercury to 15 micrograms per week but this level is commonly exceeded. Studies have shown Floridians eat more fish on average than the amounts assumed in setting standards and most Gulf Coast saltwater fish have levels of mercury above government health standards and levels documented to often cause adverse health effects(16.5).
Mercury Health and Wildlife Standards:
The FDEP NOEL for mercury of .1 ppm is also widely exceeded. The FDEP PEL for mercury is 1.4 ppm. The FDA action level for mercury in seafood is 1 ppm(59). The historic U.S. EPA mercury wildlife guideline, adopted by most states including Florida, is 12 nanograms per Liter( ng/L)(1.5)
The mercury health standard to protect human life is 0.3 parts per million(ppm) in fish and shellfish
and 7.9 ng/L for rivers and 3.5 ng/L for lakes under default water conditions. The EPA mercury wildlife standard( adopted only for the Great Lakes and tributaries) is 1.3 ng/L and the corresponding human health criteria is 3.1 ng/L(1.3).
(16) Tin, thallium, platinum, and gold can also be methylated in water bodies and sediments to very toxic methyl forms. The extremely toxic tin compound used in marine paints, tributyltin, was found at levels above the EPA toxics criteria (TBT>1ppb) in 39% of Fla. Gulf Coast sediments tested(38). In addition, the metalloids arsenic, selenium, and tellurium can be converted to volatile products of extreme toxicity(11,3.5). The EPA contaminant criteria for selenium is 1ppm. For silver, the sediment NOEL is 0.5, which is exceeded in some parts of the state(3.7), and the PEL is 2.5.
Arsenic is on the EPA Special Health Hazard List because it is a potent Class A carcinogen in humans(1.2,11.7,11.8), as well as being neurotoxic. An EPA study of cancer incidence for different levels of arsenic in drinking water found a dose related response for all types of cancer(11.3). The cancer rate for people with drinking water levels of above .6 parts per million arsenic were approx. 3 times those for people drinking water below .3 ppm arsenic, with large increases in cancers of internal organs. According to U.S.EPA it also causes birth defects, learning disabilities, damage to bone marrow, and other health problems., and new studies estimate that drinking water contaminated with arsenic at the current federal limit poses a 1 percent lifetime risk of cancer- about the same as radon or tobacco smoke(11.5). EPA staff have proposed lowering the drinking water standard for arsenic substantially to 3 to 5 parts per billion. Arsenic is acutely toxic to marine organisms but also has other effects at lower levels including growth retardation and reproductive failure(3.5). Arsenic is widely distributed in sediments in some areas of Florida and bioaccumulates in the food chain. The FDEP NOEL(no observed effect level) for arsenic is 8 ppm. The FDEP sediment PEL is 64 ppm. The EPA contaminant criteria(38) for arsenic in seafood is 2 ppm.
17. Aluminum is neurotoxic and appears to be a cause of Alzheimer's disease and other neurological disorders(15.1). Yale Univ. researchers found that a population of elderly with high aluminum levels had a much greater incidence of neuropsychiatric deficits, including poor memory and impaired visual motor coordination. A study in Great Britain found that Alzheimer's disease was 50% higher in water districts where the aluminum concentration in drinking water exceeded .11 mg/liter compared to districts with less than .01 mg/liter(15,15.1). Similar findings are available for most developed countries, including the U.S. Aluminum has also been shown to cause learning disabilities in children(15.3). The rate of American's reported dying from Alzheimer's disease has increased 1000% in the last decade(a portion of this increase is due to increased doctor awareness)(15.5). Americans are widely exposed to aluminum through food and medicines, as well as breathing wind blown aluminum particulates(along with other toxic metals)(15.1). Yale Univ. researchers estimate that over 100,000 deaths due to metallic pollution particulates occur in the U.S. each year, and such particulate pollution is increasing in many areas. Investigators found that the constituent metals and their bioavailability determine the acute inflammatory response of PM samples in lung tissue(30.5).
Aluminum is widely dispersed in soils and is a major factor in the adverse effects on fish and wildlife in acidified lakes.
18. A significant positive correlation was found between the level of nickel in drinking water and the rate of bladder and lung cancer in men. The higher the level of nickel, the higher the cancer rate(16). Nickel carbonyl is extremely
toxic and is formed when nickel is burned in the presence of carbon monoxide. Chronic low level exposure can cause serious lung damage, birth defects, kidney disease, lung cancer, etc. (16.3,28,1.2). Beryllium which is released in fossil fuel combustion is highly toxic; chronic inhalation exposure can cause lung degeneration, lung cancer, adrenal gland and immune system impairment, etc.(1.2)
The Federal safety standard is 2 micrograms per cubic meter of air, but some
exposed at levels lower than this have had serious lung damage.
19. High levels of copper over long periods can damage the brain, kidneys, cornea, etc. Copper levels in drinking water(from copper pipes) exceeding EPA standards were found in several Florida counties including: Orange, Seminole,
Pasco, Duval, and Hillsboro(15.9). Chromium is neurotoxic and a class A human carcinogen(EPA,1.2).
20. Vanadium and beryllium have been shown to cause acute and chronic respiratory disease, as well as causing other serious health problems including cancer (28,29.1,29.4,30.3). Vanadium causes lung damage and inflammation by several mechanisms, including damage to pulmonary alveolar, interruption of cytokine function, altered macrophage and Ifn response, etc. (29.2,29.9,30.3) - resulting in lung damage lung infections, bronchopulmonary disease, asthma, and lowered resistance to infectious microorganisms. Vanadium is also cytotoxic causing extensive cell death through toxic accumulation and free radical inducement(29.5). Vanadium also causes extensive DNA damage in cells and is a reproductive and developmental toxin(29.6), as well as a proven carcinogen(29.4,30.1,30.2). Vanadium is a major factor in lung damage caused by PM10 particulates in oil fly ash air pollution(29.1,29.8).
Thallium intoxication is characterized by the development of painful peripheral neuropathy, alopecia, mental disorders, and in severe cases, respiratory failure and death. Toxic optic neuropathy is also a feature. Opthalmologic features of thallium poisoning include optic neuropathy,
blepharoptosis, lens opacities, and opthalmoplegia(61). Thallium is common in coal plant emissions and phospho-gympsum waste in Florida.
Vaporized ash from burned residual oils has been shown to cause serious lung injury and respiratory disease by causing cellular death of immune suppressor cell macrophages(29.9). Such damage by small particles in the urban air has been fond to cause over 60,000 deaths per year from lung damage(29.3). EPA studies and other studies have determined that toxic metals in the dust are a major factor in the induced lung damage, and that vanadium is a particularly toxic to such macrophages in the lung(29.1,30.3,30.5). Investigators found that the constituent metals and their bioavailability determine the acute inflammatory response of PM samples in lung tissue(30.5).
High levels of manganese cause manganese madness and result in violent and antisocial behavior(15.1). Studies have found a very significant positive relationship between criminals convicted of violent crime and the level of manganese in hair samples. Manganese has been found to damage the male reproductive system resulting in infertility(10.2), to damage normal hormone production, and to be toxic to the brain, causing neurologic damage including reduced production of the brain neurotransmitter dopamine and excess production of acetylcholine(10.4). A population exposed to manganese in the water supply has experienced severe neurologic and muscle control problems(10.6).
II. Mercury in Fish and the Food Chain of Lakes and Streams and Bays
21.Studies by Univ. of Florida scientists have found that human activities are increasing the quantity of mercury delivered to the atmosphere, soils, sediments, water bodies, and food chain(17.2,28.5,1.5). Mercury accumulation rates in the Everglades reached an average of 6.4 times higher than 1900, with most of the increase since 1940. Atmospheric emissions are the largest source of mercury in lakes, and the main sources of emissions are municipal incinerators, medical waste incinerators, and coal combustion(2,2.1,16.2-17,18,18.9,22.2-23.4, 28,28.7,33,34,35). The rain in areas with incinerators like Broward County has been found to be unusually high in mercury, higher than industrial areas around Lake Michigan(28.3). Some pollution controls have been mandated for incinerators to reduce levels from incinerators and the level of mercury in the everglades appears to be declining some. Ozone pollution and reactive compounds containing chlorine or bromine oxidise elemental mercury to inorganic mercury which is more readily depositied by rain(16.7). Recent studies have found high levels of mercury in the rain all over Florida and throughout the U.S.(1.5). Over a 6 year period, Florida rain samples ranged from 1.3 nanograms/Liter to 81.2 ng/L, depending on location and climatic considerations, with an average of 12.6 ng/L(1.5). The level of mercury in Florida rain sampled exceeded the EPA human health criterion for Hg in lakes in over 97% of samples. Studies by EPA and municipal sewer agencies have also shown that sewer sludge has significant levels of mercury all over Florida, with the main sources being dental offices and excretion by those with amalgam dental fillings(14.9). Studies by Oak Ridge National Laboratory for FDEP have documented that mercury in sewer sludge and landfills is methylated to methyl mercury by soil bacteria and much of the mercury ends up in crops if land spread and in the atmosphere and rain if not(14.9). Thus mercury from dental amalgam is a major source of methyl mercury in rain. Mercury from sewers is also a significant source of mercury in rivers, lakes, bays, and fish(14.9).
22. Mercury in Salt-Water Fish and Shellfish
Studies document that Florida Saltwater
fish and shellfish have high levels of mercury in large parts of the state(21.3,22.5,33.5,59.7,33). There are fish consumption
warnings/limits for king mackerel and shark in all parts of the state and
consumption warnings on jack crevalle, spotted sea
trout, Spanish mackerel in several estuaries, and on gafftopsail
catfish, and lady fish in Tampa Bay (21.3,33.5). Some
areas such as North Florida Bay and offshore Tampa Bay have test levels higher
than most other areas(21.3).
Based on the tests that have been done, five saltwater species(king mackerel, black grouper, florida smoothhound, great while shark, tilefish) have average mercury levels on tested samples higher than the FDA action level of 1 part per million(ppm) for fish(21.3,22.5,59.7); 17 species have average mercury test levels above the FDA warning level(0.5 ppm) for mercury in fish(barracuda, black drum, blacktip shark, bluefish, bonefish, bonnethead shark, bull shark, cobia, snook, greater amberjack, jack crevalle, ladyfish, lemon shark, red drum,rock bass, spanish mackeral, spotted bass, stone crab) , and 16 species of fish(blacknose shark, blue crab, gafftopsail catfish, gag grouper, grouper, gulf flounder, permit, red grouper, sand trout, sheepshead, silver seatrout, southern flounder, tarpon, tripletail, white bass, yellow bass, yellow jack), as well as crabs, oysters and shrimp have average test levels near the warning level or some that tested above the FDA action level(21.3,59.7) and all were above the EPA health criterion of 0.3ppp(1.6). All of these have average levels of mercury above the U.S. EPA health criterion for methylmercury of 0.3 ppm(1.6). Studies (22.5) have also found that the level in most large predator species on the Gulf Coast is higher than levels found to adversely affect health(66,67) with mercury contamination being pervasive along the whole coastal area, and that people who eat Gulf Coast fish at least once per week usually have dangerous levels of mercury(22.5). 29% of a coastal sample from Florida, Alabama, and Mississippi ate fish at least once per week(22.5). Several studies including a large CDC study have found those with higher levels of mercury have higher rates of neurological problems, cardiovascular problems, infertility, and cancer(66,67,58,1.8,27.7,14.7). Another study found infertile couples were significantly more likely to have elevated mercury levels than the infertile couples, which was the case for both men (35 percent versus 15 percent) and women (23 percent versus 4 percent). Furthermore, patients who reported eating high levels of seafood showed a clear trend towards elevated mercury levels(67a,f).
A California health clinic study reports that of a California population that eats at least 2 servings of fish per week, 89% had levels of mercury in the blood exceeding 5 micrograms per liter(ug/L), the level considered the safety limit for mercury by U.S. EPA and the National Academy of Sciences(67a). Over 50% had levels over 10 ug/L and 15% had levels over 20 ug/L. The group had chronic health effects including depression, loss of scalp hair, metallic taste, headaches, arthritic pain in joints, irritability, tremors, and numbness and tingling in hands and feet. She also described cognitive problems such as pronounced memory loss, confusion and difficulties in talking. In some cases, those problems were so severe they interfered with the ability to earn a living or attend school. In all cases, health effects improved after several months of avoiding eating fish. Some women in the group were found to have transferred excessive mercury to their infants solely through their breast milk. One breast-fed baby had three times the EPA's safe level for mercury by the time he was 4 months old; and another had 4 times the EPA safe level at 19 months. Some of the infants with high mercury levels suffered severe neurological problems such as autism, and improved when treated for mercury toxicity.
The Mobile Register studies(22.5) have also found that fish and shellfish that feed near offshore oil and gas platforms have significantly higher levels of mercury than other areas(22.5) due to mercury used in drilling. Over 200 tons of mercury has been added to the Gulf through drilling over the last 30 years. More fishing occurs near such platforms since shellfish and fish tend to congregate in such areas. Other known major sources of mercury throughout the coastal area are air emissions and sewer outfalls, with some other large local industrial sites such as chlor-alkali plants. Accumulation of atmospheric oxidants and mercury can cause high levels of mercury deposition in coastal areas when activated by sunlight, which can result in very high levels of mercury in fish and wild life(68).
The U.S. FDA recommends that pregnant women entirely avoid eating shark, swordfish, king mackerel and tilefish(59.5), because a significant portion of these types of fish have mercury levels above the FDA action level of 1 ppm. However other studies(66,67) including one by the National Academy of Sciences(63) have found the old FDA action level of 1 ppm is obsolete and not adequate to protect the public, as adverse effects have been found for those eating fish at least once per week at average mercury levels below the FDA warning level of ˝ ppm(66).
Based on this a coalition of organizations using the name Environmental Working Group(EWG) did a large study to more fully assess mercury exposure effects and safety limits(59.7). In addition to the FDA limits, EWG advises pregnant women, nursing mothers and all women of childbearing age, should not eat tuna steaks, sea bass, oysters from the Gulf Coast, marlin, halibut, pike, walleye, white croaker, and largemouth bass(59.7). And that these women should eat no more than one meal per month combined of canned tuna, mahi-mahi, blue mussel, Eastern oyster, cod, pollock, salmon from the Great Lakes, blue crab from the Gulf of Mexico, wild channel catfish and lake whitefish. The EWG analysis was based on 56,000 test results on mercury in fish from 7 different government agencies, and toxicity studies by U.S. CDC and National Academy of Sciences.
However EWG recognizes that fish is an important health food with nutrients and essential fatty acids hard to substitute from other sources. The following fish are safer choices for avoiding mercury exposure: farmed trout or catfish, shrimp, fish sticks, wild Pacific salmon, croaker, haddock, some varieties of flounder, and blue crab from the mid-Atlantic. (59.7)
*******
22.5. Dangerous levels of mercury(above 1.5 ppm) have been found in over one third of the sharkmeat tested throughout the state of Florida(19.3). A survey conducted by the Minnesota Dept. Of Agriculture of swordfish offered for sale in Minnesota grocery stores found levels of methyl mercury that are higher than the Federal action guideline in over half of the samples(24.9). A joint health advisory warning of the danger of consuming sharkmeat was issued by the Fla. Dept. of Agriculture and the Dept. of Health & Rehabilitative Services(19.7). Florida commercial fishermen sold over 6.8 million pounds of sharkmeat in 1989, 36% of the U.S. total. Health warnings have also been issued by the Fla. Dept. of H.R.S. for sea trout, bluefish, king & Spanish mackerel, catfish, ladyfish, etc.(33,16.5), and other ocean fish such as tuna and swordfish have high levels. Florida Bay cormorants have also been found to have high levels of mercury(14.3).
23. Mercury in Fresh Water Fish and Wildlife
Studies have found that freshwater predator fish such as bass, pickerel, and bowfin have high levels of mercury in most of the state, with fish consumption warnings issued(21.3,33,33.3,16.5,17,17.9). Eight other species (alligator gar, black crappie, white crappie, blue catfish, flathead catfish, brook trout, drum, striped bass) have average test levels near the FDA warning level or some tested above the FDA action level(21.3). Over 2 million acres of Florida’s surface waters have fish with high levels of mercury, averaging above the FDA/EPA warning level of 0.5 parts per million(33.3) and even more above the U.S. EPA mercury health criterion of 0.3 ppm(1.6). The major source of mercury into these water bodies is air deposition that is brought down in rain. A Florida emissions inventory found that the major sources of atmospheric mercury were municipal solid waste combustors (MSW), electric utility industry, and medical waste incinerators(33.3), but incinerator emissions have been reduced in recent years. The most vulnerable groups to mercury exposure are women who are pregnant or might become pregnant, nursing mothers, and young children(65,59.5,59.7,7.5,5.5). These groups should limit consumption of freshwater fish to no more than one meal per week (6 ounces of cooked fish for adults and 2 ounces of cooked fish for young children). Other animal species that eat fish and crawfish, such as cormorants, wading birds, raccoons, alligators, mink,etc. and panthers which eat raccoons have also been found to have dangerous levels of mercury and are have been adversely affected(1.5,17.4-17.7). Three panthers along with many birds that eat fish have died from mercury poisoning and others have very high levels of mercury(14.3,17.4). The majority of Florida panthers in south Florida have high levels of mercury and have had reproductive systems and hormone levels disrupted to the extent of not being able to reproduce. The majority of male panthers were found to have estrogen levels higher than testosterone levels due to estrogenic effects of the mercury and perhaps other estrogenic chemicals in the fish(14.3).
23.5 Studies by the Wisconsin Dept. of Natural Resources(18.4) and Univ. of Wisconsin researchers(18.6,16.3,2.1) found hundreds of lakes and streams in Wisconsin with mercury in fish at above the recommended levels for eating, and concluded the major source of the mercury appears to be air emissions. They also found that one gram of mercury deposition is enough to cause the need for a fish consumption limitation in a 25 acre lake, and that mercury concentrations of 2 parts per trillion(parts per trillion(ppt) in lake water often result in concentrations in fish sufficient to require consumption advisories(Watras,18.6 &16.3,18) Warnings on eating fish have been issued for thousands of rivers and lakes throughout the U.S. and Canada(64), for approx. 20 % of all U.S. lakes including all Great Lakes.
The Minnesota Pollution Control Agency(MPCA) has also found widespread dangerous levels of mercury(as much as 4.5 micrograms per gram of fish) in 94% of the hundreds of lakes and streams tested in Minnesota (18.8,18.9, 16.3). MPCA studies estimated that virtually all of the mercury in Minnesota lakes come from emissions, with the largest amount from incinerators and coal plants (18,18.9). They concluded that mercury emissions are a larger threat to the states water resources than acid rain, though acidity level is also a factor in the level of mercury and other toxic metals in fish(18.9).
Mercury deposition levels on the surface of lakes in Minnesota were 12 to 14 micrograms per square meter per year. Precipitation measurements in Minnesota were found to have an average mercury concentration of 19 ppt. Levels in sediment in recent years are more than 3.5 times levels in sediment prior to 1900, and approx. 25% of the mercury deposited in a lake catchment area is exported to the lake(18.8). Mercury in the areas atmosphere has increased an average of 2% per year, compared to a 1.5% increase over the N. Atlantic Ocean which also was found to be primarily due to manmade emissions. Deposition levels were found to be increasing throughout the area due to long range transport, but was highest near emission sources. Worldwide mercury atmospheric levels are now at least 3 times the level of 1900, and there is much more mercury in aquatic ecosystems than in past times(24.5), as shown by analyses of polar ice cores, lake sediment cores, and peat cores.
Because of the widespread high levels of toxic metals in fish and the food chain in Minnesota and neighboring Great Lakes states, Minnesota requires emissions limits on lead and mercury for municipal incinerators. The emission limit for mercury was .002 pounds per ton for a 1990 incinerator permitted(18.3). The most recent study recommended emission limits should be no more than 50 pounds per year, whereas current EPA limits are 20,000 pounds(18.9).
24. According to EPA spokesmen, Gary Glass and Ray Morrison, mercury has been found to be entering the food chain throughout the U.S. At least 40 states and 2 Canadian provinces have limited or banned consumption of fish from thousands of affected lakes and rivers in both the U.S. and Canada(19,16.3,33). Mercury has been found to be adversely affecting loons, eagles, ospreys, otters, and mink in the Great Lakes area(28).
Studies by the Electric Power Research Institute, the research arm of the electric utility industry, have confirmed that atmospheric deposition of mercury accounts for most of the mercury accumulating in fish in seepage lakes and that increased acidity enhances mercury accumulations in fish(18 & 18.1). Approx. 90 % of the mercury in fish is methyl mercury, the most toxic form to humans. Based on their research, EPRI believes that most older estimates of mercury levels are inaccurate and questionable, and that clean sampling/clean lab procedures are required for accurate sampling of mercury. Reported mercury removal levels by wet scrubbers have a very wide range, from 25% to 90%, but all of the reported data should be considered questionable(18).
Municipal waste and coal contain large amounts of toxic metals such as mercury, lead, cadmium, etc.; large volumes of toxic metal emissions are occurring where stringent controls on incinerator fuel sources and stack emissions are not in effect(18.3) as they are in some European countries.
26. The toxic metals most dangerous to people eating fresh water fish are those that accumulate in the edible muscle of fish‑ including mercury, arsenic, radioactive cesium, and to a lesser degree lead(19.9). Most toxic metals such as lead, cadmium, aluminum, etc. accumulate primarily in internal organs, fat, fins, and mucus under the skin(25.8).
II(b). Bioaccumulation of Toxic Metals in Marine Fish and Shellfish
27. Shellfish, especially oysters, accumulate lead, mercury, cadmium, copper, silver, arsenic, and radioactive metal isotopes(19.9,3.7). Oysters and other shellfish are accumulating increasing amounts of toxic metals, with oysters often accumulating levels of cadmium, lead, and arsenic dangerous to people and above the FDA recommended action level or guideline level(59). The following table gives a summary of some of the levels of toxic metals found in shellfish in Florida.
The data for the Indian River Lagoon is for an area with lower levels of metals in sediments than some other urban coastal areas in Florida. The FDA Action Level is the level at which commercial seafood may be removed from sale; however it is based primarily on acute toxicity criterion and does not take into account that some of the metals such as mercury, lead, and cadmium have been found to be endocrine system disrupters at relatively low levels and several of the metals are carcinogenic, neurotoxic, and immunotoxic. While there is no FDA Action Level for arsenic, arsenic is more acutely toxic than the other metals for which there is an action level and arsenic is highly carcinogenic(11.7,11.8). The drinking water guideline for arsenic is lower than those for mercury or cadmium. The EPA toxics contaminant criteria for arsenic in seafood is 2 ppm(38).
Range of Toxic Metals Observed in Florida Shellfish (ppm-wet weight*)
Metal Oysters Clams
FDEP 1984 N.O.A.A 1983-1992 FDEP 1984 I.R.L. 1992 FDA EPA source: (3.9) source: (3.7) source:(3.9) source:(3.7) Action Crit.
min/mean/max min to max min/mean/max min to max Level Level
Arsenic .05/ 1.5/ 7.8 1.0/ 4.6/9.5 ** 2 Cadmium .10/ .48/ 1.6 .70 to 5.1 .05/ .35/1.1 .01 to 0.15 1.0 0.5 Chromium .005/.15/ .64 .20 to 0.9 .06/.30/1.28 .03 to 0.08 11 1
Copper .50/ 7.3/28.4 .50/1.5/4.7 1.0 to 4.0 15
Lead .005/.14/1.36 .10 to 1.6 .05/.67/6.5 .04 to 1.73 1.2 0.5
Mercury .001/.017/.05 .10 to .16 .001/.02/.04 .001 to .018 1.0 1
Nickel .005/ .23/1.1 .06/.72/2.6
Selenium .10/ .36/ .67 .18/.45/1.0 1
Zinc 34/ 205/ 546 1 / 12/ 25 1.7 to 53 60
* Indian River Lagoon data was calculated dry weight basis. Since all other data shown here is wet weight, the data for I.R.L. was converted to wet weight by assuming water content of clams was 85%.
From the table it is seen that the FDA Action level for cadmium and lead appear to be often exceeded by oysters and clams from some polluted coastal areas of Florida, and the EPA contaminant criteria for arsenic in seafood. This could indicate that people eating seafood regularly from such a polluted area could experience serious health problems over time. To date there has apparently been no health warnings for shellfish comparable to the warnings for mercury in freshwater fish, even though FDA Action levels may be exceeded by similar levels. In a controlled study, oysters exposed to 10 micrograms per liter of cadmium in water accumulated 18 ppm of cadmium(3.9). None of the cadmium levels in the limited surveys done in Florida have reached this level, but some areas of the state have higher levels of cadmium in sediments than the sampled areas. The Indian River Lagoon study(3.7) noted that areas with the highest levels of metals in sediments were toxic to clams so no clams in these locations could be sampled and all clam samples came from less polluted sites. Mussels and crabs have been found to accumulate cadmium inversely with the salinity or alkalinity of water(19.9).
The Canadian Food and Drug Admin. has established 2 ppm as the maximum safe concentration of lead in fish. Due to recent studies of lead and learning disabilities, some researchers believe this level is too high and a lower guideline is recommended by the FDA of 1ppm. As seen from the sample data oysters often accumulate levels higher than this. Levels of 2 micrograms per liter in water often mean levels in oysters of more than 2 ppm(19.9). Some U.S. rivers have above 20 micrograms per liter of lead in some areas. Increased acidity increases the availability of lead, and fish at PH 6.0 accumulate 3 times as much lead as at PH 7.5 for the same concentration of lead in water.
Arsenic accumulates in shellfish and has been found at levels 20 times the EPA guideline maximum contaminant level(19.9). The toxic arsenite form is the primary form in shellfish and the most toxic form to people. Radioactive cesium is dangerous to people and is discharged from nuclear power plants. Large amounts of radioactive isotopes are discharged into Florida water bodies by coal plants and phosphate mining, and have been found in shellfish. Toxic metals have been found in Florida shellfish in several areas of the state (19.5,3.7).
Crabs and fish often accumulate high levels of copper which has an adverse effect on fish survival, but doesn't usually affect people because the accumulation is not primarily in muscle tissue. Oysters and squid accumulate copper to dangerous levels however; copper use as an algicide and water weed killer is a common source and has been found to cause elevated copper levels in water and sediments in some areas of the state such as the Crystal River.
Atmospheric metal emissions to oceans are significantly altering the marine cycle of the toxic metals(2,2.1). Oceans near areas with high fossil fuel combustion have much higher levels of mercury and other toxic metals, with atmospheric emissions being the main source of mercury in coastal waters. Mercury gets into ocean fish and shellfish similarly to freshwater fish.
A high percentage of coastal bay and estuarine sediments tested in Florida have been found to have significantly elevated levels of toxic metals(36), and sediments in Gulf Coast areas were found to be toxic to marine organisms in 9 percent of the estuarine area(37).
III. Effect of Toxic Metals on Forests and Plant Ecosystems
28. Some metals are toxic to nitrogen-fixing bacteria associated with root-systems of legumes(28). Nitrogen and phosphorus cycling in soils can also be adversely affected by some metals. In addition, litter decomposers can be destroyed by some metals. All of these effects are made worse by acidity.
29. Heavy metals from atmospheric emissions are deposited on leaves and soils of forests and cropland. Crop plants have been shown to directly absorb and retain mercury and other toxic metals through leaf uptake(22.8,2). The interaction of the heavy metals and acid deposition is a factor in the extensive forest decline occurring throughout Europe and North America(20, 20.2). Increased levels of toxic metal emissions are leading to rapid buildups of trace metals in soil and water and likewise to buildups in plants and the food chain, especially in industrial areas and near large emission sources(2). Levels in the U.S. and Europe with large emission sources are currently doubling every 3 to 10 years. The level in plants and crops has reached levels that damage plants and cause human health damage in some areas(2,22.4) and is approaching such levels in many other areas. The loading of the air and environment in urban industrial areas with toxic metals is a major health concern for the next and future generations, but the extent of metals emissions is so large and widespread that even the air of the most remote areas of the arctic and antarctica have significant levels(2).
The solubility of aluminum in soils and other heavy metals (lead,cadmium,zinc,etc.) being deposited on leaves and soils by air pollution increases with increasing acidity. Canada has issued a health warning for Central Canada against eating the livers or kidneys of game animals because of cadmium buildup in the food chain(2). The main sources of such toxic metal emissions are atmospheric emissions.
Mercury and other toxic metals have also been found to be accumulating in the forest floor of European forests; the humus of Swedish forest floors are estimated to contain over 600 tons of mercury. Both inorganic and methyl mercury are toxic to spruce seedlings, suppressing chlo