Bioremediation of Polychlorinatedbiphenols in Soil and Groundwater

BIOREMEDIATION OF POLYCHLORINATEDBIPHENOLS IN SOIL AND GROUNDWATER

ES4

PRESENTED BY

MARGARET CASEY

KIRSTY MC CORMACK

DECEMBER 2005

LECTURER: DR. MICHEAL BROADERS

CONTENTS

CONTENTS2

SECTION 1. INTRODUCTION3

1.1 Bioremediation3

1.2 History of Polychlorinated biphenyls3

1.3 Distribution in the Environment5

1.3.1 Aquatic systems 6

1.3.2 Air systems7

1.3.3 Soil systems8

1.4 Toxicities 9

1.4.1 Endocrine Effects9

1.4.2 Other non- cancer affects9

1.4.3 Immune affects10

1.4.4 Reproductive affects11

1.4.5 Neurological effects 12

1.5 Creosotes13

1.6 Different types of Creosotes 13

1.7 Health affects14

1.8 Factors modifying toxicity14

1.9 Uses of Creosotes15

1.10 Creosotes in the environment16

1.11 Chemical properties18

SECTION 2. DISSCUSSION19

2.1 Biodegradation of Polychlorinated biphenyls19

2.1.1Aerobic Oxidative Dehalogenation19

2.1.2Anaerobic Reductive Dechlorination20

2.2 Legislation22

2.3 Degradation of Creosotes in the Environment23

2.3.1 Sediment and Soil23

2.3.2 Water24

2.3.3 Air25

2.4 Legislation regarding Creosotes26

2.5 Case studies (PCBs)28

SECTION 3. CONCLUSION30

SECTION 4. REFERENCES31

APPENDICES32

1. Introduction

1.1 Bioremediation

Bioremediation is a technique that uses the bacteria or other organisms to clean up contamination. Bacteria generally break down the contamination into less harmful components, such as carbon dioxide and water. Bioremediation can be used to clean up soil or water. Water and nutrients, such as fertilizer and oxygen, may be added to the contaminated soils to speed up the breakdown process. Some chemicals, such as gasoline, are easily bioremediated while other, such as pesticides, can not be effectively treated using bioremediation. The contamination can be treated in place (in situ) or the material can be excavated and treated above ground in a different location (ex situ). Types of soil bioremediation methods include landfarming, composting, land spreading, biotreatment, and biopiles. Types of water bioremediation include natural attenuation, and engineered wetlands. (K. McCormack)

1.2 History of polychlorinated biphenyls

Polychlorinated biphenyl (PCB’s) is the collective name applied to a group of aromatic chlorinated chemical compounds which are now banned but were used extensively up until the late 1980’s. they were used for transformers, capacitors, as heat exchange fluids, lubricating oils and as additives in paint and plastic.

PCB’s are a mixture of up to 209 individual chlorinated compounds. There is no known natural source of PCBs. They are colourless or light yellow. They can exist as a vapour in air; they have no taste or smell.

Polychlorinated biphenyls were first produced in 1929 for a wide variety of uses, these ranged from being an extender in insecticide production to being used as an insulator in transformer production. They have very useful properties that may be amplified by mixing different PCB congeners. It is these unique physical properties that made them attractive compounds for industry. Their production increased exponentially from 1,000,000 kg in the 1930’s to an estimated high of 20 x 108 kg in 1975, this was due to more uses for them.

The first indication that PCBs may be damaging to the human health was four decades after they were first introduced. Studies suggested that PCBs may pose a serious threat to humans, there were also indications of wide spread distribution throughout the environment, it was becoming evident that PCBs were having a negative impact on many biological systems, PCBs eventually became a public issue, leading to the banning of its production by government legislation. ( toxicological profile for PCBs) (K. McCormack)

1.3 Distribution in the environment

Although the amount of PCBs produced annually since the 1970’s has decreased, this does not mean that the toxicological threat posed has also decreased. There are very little safe disposal options for PCBs, for example, in Germany PCBs are being buried in the shafts of salt mines. By doing this, residues will eventually find there way to watercourses and to the sea. (Phillips, 1994)

Therefore ecotoxological problems created by PCB contamination will be evident for many years to come. PCBs are widespread contaminants in the environment, primarily in soil and freshwater systems. (Erickson 1986)

Their presence in the environment has been of growing concern due to their low degradability, toxicity, mutagenicity because of their tendency to bio accumulate. PCB contamination in the environment is mainly as a result of human activities as they are not known to occur naturally in the environment, thus high PCB concentration areas tend to be around industrialised areas. PCBs enter the general environment mainly by leakage of supposedly closed systems, from landfill sites, incineration of waste, agricultural lands, industrial discharges and sewage effluents. PCBs are also widely dispersed in the atmosphere where they are transported by winds and fall to the surface in precipitation. Approximately 98% of the PCBs entering the ocean are currently deposited form the atmosphere. Factors such as air temperature, wind speed, storm frequency, rainfall rates and the volatility of individual PCB isomers influence the pattern and rates of PCB movement in the atmosphere. The principal transport route for PCBs through aquatic systems is from waste streams into receiving waters, with further downstream movement occurring by solution and readsorption onto particles as well as by the movement of sediments. This leaves the marine environment as one of the final sinks for PCBs. (K. McCormack)

1.3.1 Aquatic systems

PCBs are found in higher concentrations in the sediments of aquatic systems due to their chemical and physical properties which cause high sorption reactions. Sorption increases with chlorine content, surface area and with the organic content of the sorbent. Therefore, PCBs sorb onto falling sediments that eventually end up as bottom sediments. PCBs are associated particularly with suspended sediments of a diameter less than 0.15mm (US EPA, 1980). The release of PCBs from sediments to overlying waters can occur by slow desorption, especially when PCB concentrations are high or when sudden hydro graphic activity like flooding or dredging causes sediments to be resuspended and redistributed. Translocation can also occur through biological activity. Desorption of PCBs from particulate is more likely to occur from lower chlorinated, more water-soluble PCB congeners. (K. McCormack)

1.3.2 Air systems

(Great Lakes) - Airborne contamination has been recognized as a significant source of PCB contamination in the Great Lakes Basin since the mid-1980’s. This is especially true for Lake Superior which is still largely isolated from industrial and municipal sources (Hileman, 1988).

Many of the sources of airborne PCBs to the Great Lakes Basin, especially those with unusually high concentrations, tend to originate from the southern U.S., Mexico, and Latin America. (K. McCormack

1.3.3 Soil systems

Sorption reactions also affect transport in soils. PCBs that are sorbed by soils, especially highly chlorinated ones, remain significantly immobile against leaching. They are also unlikely to be taken up by plants and therefore are not readily mobile in soil systems. However, because PCBs have a moderate vapour pressure, vapour phase transport may allow for redistribution or migration through the saturated soil pores. (K. McCormack)

1.4 Toxicities

1.4.1Endocrine Effects

There has been significant discussion and research on the effects of environmental contaminants on the endocrine system ("endocrine disruption"). While the significance of endocrine disruption as a widespread issue in humans and animals is a subject of ongoing study, PCBs have been demonstrated to exert effects on thyroid hormone levels in animals and humans. Thyroid hormone levels are critical for normal growth and development, and alterations in thyroid hormone levels may have significant implications.

It has been shown that PCBs decrease thyroid hormone levels in rodents, and that these decreases have resulted in developmental deficits in the animals, including deficits in hearing. PCB exposures have also been associated with changes in thyroid hormone levels in infants in studies conducted in the Netherlands and Japan. Additional research will be required to determine the significance of these effects in the human population. (K. McCormack)

1.4.2 Other Non-cancer Effects

A variety of other non-cancer effects of PCBs have been reported in animals and humans, including dermal and ocular effects in monkeys and humans, and liver toxicity in rodents. Elevations in blood pressure, serum triglyceride, and serum cholesterol have also been reported with increasing serum levels of PCBs in humans.

In summary, PCBs have been demonstrated to cause a variety of serious health effects. PCBs have been shown to cause cancer and a number of serious non-cancer health effects in animals, including effects on the immune system, reproductive system, nervous system, and endocrine system. Studies in humans provide supportive evidence for the potential carcinogenicity and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated, as alterations in one system may have significant implications for the other regulatory systems of the body. (K. McCormack)

1.4.3 Immune Effects The immune system is critical for fighting infections, and diseases of the immune system have very serious potential implications for the health of humans and animals. The immune effects of PCB exposure have been studied in Rhesus monkeys and other animals. It is important to note that the immune systems of Rhesus monkeys and humans are very similar. Studies in monkeys and other animals have revealed a number of serious effects on the immune system following exposures to PCBs, including a significant decrease in size of the thymus gland (which is critical to the immune system) in infant monkeys, reductions in the response of the immune system following a challenge with sheep red blood cells (a standard laboratory test that determines the ability of an animal to mount a primary antibody response and develop protective immunity), and decreased resistance to Epstein-Barr virus and other infections in PCB-exposed animals. Individuals with diseases of the immune system may be more susceptible to pneumonia and viral infections. The animal studies were not able to identify a level of PCB exposure that did not cause effects on the immune system.

In humans, a recent study found that individuals infected with Epstein-Barr virus had a greater association of increased exposures to PCBs with increasing risk of non-Hodgkins lymphoma than those who had no Epstein-Barr infection. This finding is consistent with increases in infection with Epstein Barr virus in animals exposed to PCBs. Since PCBs suppress the immune system and immune system suppression has been demonstrated as a risk factor for non-Hodgkin's lymphoma, suppression of the immune system is a possible mechanism for PCB-induced cancer. Immune effects were also noted in humans who experienced exposure to rice oil contaminated with PCBs, dibenzofurans and dioxins.

Taken together, the studies in animals and humans suggest that PCBs may have serious potential effects on the immune systems of exposed individuals. (http:/www.epa.gov/opptintr/pcb/effects.html) (K. McCormack

1.4.4 Reproductive Effects

Reproductive effects of PCBs have been studied in a variety of animal species, including Rhesus monkeys, rats, mice and mink. Rhesus monkeys are generally regarded as the best laboratory species for predicting adverse reproductive effects in humans. Potentially serious effects on the reproductive system were seen in monkeys and a number of other animal species following exposures to PCB mixtures. Most significantly, PCB exposures were found to reduce the birth weight, conception rates and live birth rates of monkeys and other species and PCB exposure reduced sperm counts in rats. Effects in monkeys were long-lasting and were observed long after the dosing with PCBs occurred.

Studies of reproductive effects have also been carried out in human populations exposed to PCBs. Children born to women who worked with PCBs in factories showed decreased birth weight and a significant decrease in gestational age with increasing exposures to PCBs. Studies in fishing populations believed to have high exposures to PCBs also suggest similar decreases. This same effect was seen in multiple species of animals exposed to PCBs, and suggests that reproductive effects may be important in humans following exposures to PCBs. (K. McCormack

1.4.5 Neurological Effects

Proper development of the nervous system is critical for early learning and can have potentially significant implications for the health of individuals throughout their lifetimes. Effects of PCBs on nervous system development have been studied in monkeys and a variety of other animal species. Newborn monkeys exposed to PCBs showed persistent and significant deficits in neurological development, including visual recognition, short-term memory and learning. Some of these studies were conducted using the types of PCBs most commonly found in human breast milk.

Studies in humans have suggested effects similar to those observed in monkeys exposed to PCBs, including learning deficits and changes in activity associated with exposures to PCBs. The similarity in effects observed in humans and animals provide additional support for the potential neurobehavioral effects of PCBs. (www. Epa.gov/opptintr/pcb/effects.html) (K. McCormack)

1.5 Creosotes

Chemicals used in wood preserving operations that are produced by distilling-coal tar. They contain polycyclic aromatic hydrocarbons and polynuclear aromatic hydrocarbons (PAHs and PNAs) (M. Casey)

1.6 Different types of creosotes

Creosote is the name used for a variety of products that are mixtures of many chemicals; those products include wood creosote, coal tar creosote, coal tar and coal tar pitch.

Wood creosote is a colourless to yellowish greasy liquid with a characteristic smoky odour and sharp burned taste. The major chemicals in wood creosote are phenol, cresols, and guaiacol.

Coal tar creosote is the most common form of creosote in the workplace. It is a thick, oily liquid that is typically amber to black in colour, and is a distillation product of coal tar.

Coal tar and coal tar pitch are the by products of the high temperature treatment of coal to make coke or natural gas; they are usually thick, black or dark brown liquids. Coal tar has a sharp burning taste.

Coal tar creosotes, coal tar, and coal tar pitch are similar in composition; the major chemicals in them that can cause harmful health effects are polycyclic aromatic hydrocarbons, phenol and cresols. (M. Casey)

1.7 Health Effects

Eating food or drinking water with high levels of creosotes may cause a buring in the mouth and throat, and stomach pains.

Brief direct contact with large amounts of coal tar creosote may result in a rash or severe irritation of the skin, chemical burns of the surfaces of the eyes, convulsions and mental confusion, kidney or liver problems, unconsciousness, and even death. Longer direct skin contact with low levels of creosote mixtures or their vapours can result in increased light sensitivity, damage to the cornea, and skin damage. Longer exposure to creosote vapours can cause irritation of the respiratory track.

Long term exposure to low levels of creosote, especially direct contact with the skin during wood treatment or manufacture of coal tar creosote-treated products has resulted in skin cancer and cancer of the scrotum.

The International Agency for Research on Cancer (IARC) has determined that coal tar is carcinogenic to humans and that creosote is probably carcinogenic to humans. The EPA has determined that coal tar creosote is a probably human carcinogen. (M. Casey)

1.8 Factors modifying toxicity.

A major factor modifying the toxicity of creosote is sunlight, especially its UV components . This is due to the presence of photoabsorbing molecules (e.g., PAHs), which can be transformed by irradiation to reactive intermediates, thus leading to

enhanced toxicity. Larger PAHs have been found to have a greater photoreactibility than smaller ones. It is assumed that metabolites (diol epoxides) of PAHs play a major role in carcinogenesis. (M. Casey)

1.9 Uses of Creosotes

Coal tar creosote is a wood preservative and water-proofing agent for structures on land and in marine and fresh waters and for railway crossing timbers and sleepers (railroad ties), bridge and pier decking, poles, log homes, fencing, and equipment for children’s playgrounds.

The majority of creosote used in the European Union (EU) is for the pressure impregnation of wood. In the USA and many other countries, the use of coal tar creosote is limited to certified applicators.

Non-wood uses include anti-fouling applications on concrete marine pilings. Creosote can be a component of roofing pitch, fuel oil, and lamp black and a lubricant for die moulds. Other uses reported include animal and bird repellent, insecticide, animal dip, and fungicide. (M. Casey)

1.10 Creosotes in the environment

No information is available on what happens to wood creosote when it enters the environment. Coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles do not occur in the environment naturally, but are by-products produced in coke or gas manufacturing plants using high-temperature processes. Coal tar creosote is released to water and soil mainly as a result of its use in the wood preservation industry. In the past, waste water from wood-treatment facilities was often discharged to unlined lagoons where it formed a sludge. Also, companies that preserve wood with coal tar creosote may treat their water wastes in treatment plants or release the waste water to the municipal water treatment system. This is still the largest source of coal tar creosote in the environment. However, new restrictions from EPA have caused changes in the treatment methods that have decreased the amount of creosote available to move into soil from waste water effluents. Coal tar creosote contains some components that dissolve in water and some that do not. Coal tar creosote components that dissolve in water may move through the soil to eventually reach and enter the groundwater, where they may persist. Once in the groundwater, breakdown may take years. Most of the components that are not water soluble will remain in place in a tar-like mass. Migration from the site of contamination is not extensive. Breakdown in soil can take months for some components of coal tar creosote, and much longer for others. Sometimes, the small amounts of chemical remaining in the soil or water that take a long time to break down are still toxic to some animals and possibly to humans. Coal tar creosote components may also be found in the soil as a result of leaking or seeping from treated timber.