Polycyclic aromatic hydrocarbons Term paper in FMI310 – Environmental pollutants and ecotoxicology

Espen Rise Gregersen

Spring 2013

Department of Ecology and Natural Resource Management Norwegian University of Life Sciences

Student name

Student number

Course name Course code

Assignment no. Due date

Teacher/Supervisor

I hereby declare that this assignment is written by me and

- is a result of my own work

- has not been used for another exam at another department/ university/ university

college in Norway or another country.

- does not refer to/quote works of others without stating it both in the text and in the

reference list

- does not refer to/quote previous writings of my own without stating it both in the text

and in the reference list

- mentions explicitly all sources of information in the reference list.

I am aware of the fact that violation of these clauses is regarded as cheating and can result in

annulment of the examination or paper. Cheating or attempted cheating can result in the

expulsion of the examinee, in accordance with the University and College Act Chapter 14-1.

Place/Date Signature

ASSIGNMENT/ EXAM DECLARATION

Environmental Pollution and Ecotoxicology FMI310

Title of the Term paper

2

Table of Contents

Abstract ............................................................................................................... 3!

Introduction ........................................................................................................ 4!

Main part/Documentation ................................................................................. 5!Background ................................................................................................................. 5!Sources of PAHs ......................................................................................................... 5!

PAH pollution in Norway and Europe ............................................................................... 6!Bioaccumulation and bioconcentration ....................................................................... 8!Biodegradation and mechanisms for PAHs removal .................................................. 9!

Biodegradation of PAHs .................................................................................................... 9!Cytochrome P450 and the Ah-receptor ............................................................................ 10!Bioremediation ................................................................................................................. 11!

Toxicity of PAHs ...................................................................................................... 11!Carcinogenic and mutagenic ............................................................................................ 11!Immunotoxic ..................................................................................................................... 13!

Effects of PAHs on fish (Literature review) ............................................................. 13!Biochemical effects ........................................................................................................... 13!Genetic effects .................................................................................................................. 13!Immunological effects ....................................................................................................... 14!Reproductive and developmental effects .......................................................................... 14!Behavioral effect ............................................................................................................... 15!

Discussion .......................................................................................................... 16!

Conclusion ......................................................................................................... 17!

Literature .......................................................................................................... 18!

3

Abstract Polycyclic aromatic hydrocarbons (PAHs) are a unique class of persistent organic pollutants

(POPs) constituted by hundreds of individual substances. PAHs are known to be persistent in

the environment, bioaccumulate in organisms, and have carcinogenic and immunotoxic

effects on organisms. There are both natural and anthropogenic sources of PAHs, of

anthropogenic sources industry and residential wood burning is larges sources of PAHs in

Norway. Biodegradation pathways for different PAHs are similar, but the biodegradation rate

is shown to differ between LMW PAHs and HMW PAHs. PAHs have many different effects

on fish, biochemical, genetic, and immunotoxic effects have been widely studied, in addition

PAHs have potential effects on reproduction, development and behavior. PAHs are a very

important and dangerous environmental pollutant, and it is very important to study PAHs both

how they behave in the environment and what effects they have on organisms that live in the

environment.

4

Introduction Persistent organic pollutants (POPs) are organic compounds that are resistant to

environmental degradation through chemical, biological, and photolytic processes (EMEP

2012). Some of these compounds are environmentally important because they are, or can

become, carcinogenic or mutagenic (Douben 2003).

Polycyclic aromatic hydrocarbons (PAHs) are a unique class of POPs that consists of

hundreds of individual substances (Douben 2003). PAHs occur naturally as a by-product of

incomplete combustion, e.g. from road traffic, coal fires, heating, the summer barbecue. And

because of this PAHs are a frequent and troublesome environmental pollutants (Douben

2003). In many countries PAHs are priority pollutants because of their carcinogenic (cancer-

causing) properties for humans and organisms in general (Vives et al. 2004), and

benzo(a)pyrene has been known to be most carcinogenic for humans (Klima- og

forurensningsdirektoratet 2011).

Skin cancers have been documented in young chimney sweeps in London as early as

1775 and in German coal tar workers in the late 1800s, and this has later been linked to

exposure to PAHs (In:Douben 2003). Various soots, tars, and oils were shown to be

carcinogenic to humans and laboratory animals, and such complex mixtures were later found

to contain sources of PAHs, including the carcinogen benzo(a)pyrene (Douben 2003).

PAHs are known to be persistent in the environment, bioaccumulate in organisms, and

have carcinogenic and immunotoxic effects on organisms. Because of PAHs potentially toxic

effects it is very important to study PAHs. What effect is has on organisms, how mechanisms

of PAHs removal work, the fate of PAHs in the environment, and more. Knowing more about

these aspects will greatly aid our understanding of PAHs, how it behave in the environment

and its effects.

In this paper I will focus on explaining sources, effects and mechanisms for removal

of PAHs generally, with the goal of addressing the importance PAHs in an ecotoxicological

perspective then I will give a short review over the different effects that PAHs has on fish.

The goal for the paper will be to collect information about PAHs and explain why PAHs is

such an important environmental pollutant.

5

Main part/Documentation

Background

Hydrocarbons are compounds composed only of carbon and hydrogen, most hydrocarbons

exist as solids or liquids, but some can exist as gases (Walker et al. 2012). Hydrocarbons have

low polarity and are generally lipophilic. Hydrocarbons fall into to classes; (1) alkanes,

alkenes and alkynes and (2) aromatic hydrocarbons (Walker et al. 2012). Aromatic

hydrocarbons have one or more benzene rings (Walker et al. 2012).

The Polycyclic aromatic hydrocarbons (PAHs) belong to a group of organic

compounds consisting of 2 to 13 aromatic rings (Skupinska et al. 2004). All PAHs are solid

and have high melting and boiling points (Skupinska et al. 2004) and the fate of PAHs in the

environment is primarily controlled by their physiochemical properties, witch is (1) low

solubility with water, (2) low Henry’s law constant, (3) high hydrophobicity or lipophilicity

(4) low organic carbon partition coefficient, and (5) high bioconcentration factor (Morelli et

al. 2013). Generally, low-molecular-weight (LMW) PAHs are more volatile, more water

soluble, and less lipophilic than high-molecular-weight (HMW) PAHs (Morelli et al. 2013).

Sources of PAHs

There are both natural and anthropogenic sources of PAHs. Natural sources are natural

combustion processes, e.g. vegetation fires, and are responsible for a general background

level of PAHs in soils or sediments (Dreyer et al. 2005). Anthropogenic sources are mainly

from combustion of fossil fuel and industry (Skupinska et al. 2004). PAHs occur mostly in

mixtures and enter the environment via the atmosphere are adsorbed onto particulate matter

(Douben 2003).

PAHs can be broadly separated into three nonexclusive categories based on their

source: biogenic, petrogenic and pyrogenic PAHs (Thorsen et al. 2004). Biogenic PAHs are

formed from natural biological processes including diagenesis; Petrogenic PAHs are derived

from petroleum and usually enter the aquatic environment dissolved in water, air or

cosolvents such as crude oil; and pyrogenic PAHs are formed as a result of incomplete

combustion of fuels and largely enter the environment tightly sorbed to particulate matrixes

(Thorsen et al. 2004).

6

PAH pollution in Norway and Europe

The largest source of PAH pollution in Norway is industry and burning of wood for heating

(vedfyring) (Figure 1), and it is found that aluminium production have been the largest

contributor of PAHs emissions from industry (Klima- og forurensningsdirektoratet 2011).

Figure 1: Sources of PAH emissions in Norway in 2008. (Klima- og forurensningsdirektoratet 2011)

PAH emissions in Norway has been reduced the last decade, Figure 2 show that the emissions

had a stable trend from 1995 to 2005, and from 2005 to 2007 there where an almost 50 %

reduction in emission (Klima- og forurensningsdirektoratet 2011). The main reason for the

reduction was the modernization of old aluminium smelters and the out-phasing of the

søderberg-technology that have been used in aluminium production (Klima- og

forurensningsdirektoratet 2011).

7

Figure 2: Overview over PAH emissions to air (tons) for Norway, in the time period 1995 – 2008. (Klima- og forurensningsdirektoratet 2011)

In Europe the emissions of PAHs have also been reduced (Figure 3a). The most significant

sources of PAHs in Europe comes from commercial, institutional and households, with a

much less significant sources from industrial processes (Figure 3b).

Figure 3: Total PAHs emissions in the EU-27: (a) trend in total PAHs emissions from the five most important key categories, 1990–2010; (b) share of emissions by sector group, 2010 (European Environment Agency 2012).

8

Bioaccumulation and bioconcentration

PAHs accumulate in the environment especially in soil, sediments, and bioconcentrate and

bioaccumulate in organisms especially lower invertebrates (Douben 2003). Bioaccumulation

occurs when an organism absorbs a toxic substance at a rate greater than that at which the

substance is lost (Hine & Martin 2008). Bioconcentration is a related but more specific term,

referring to uptake and accumulation of a substance from water alone. By contrast,

bioaccumulation refers to uptake from all sources combined (e.g. water, food, air, etc.)

(Walker et al. 2012). PAH bioaccumulates especially in algae and lower invertebrates with

slow metabolisms, and there are found some biomagnification to higher trophic levels

(Douben 2003).

The factors affecting PAH accumulation in tissue are many, Baumard et al. (1998)

observed that the difference in PAH accumulation was governed by different feeding

behavior, trophic level and habitat. The accumulation of hydrophobic contaminants are found

to accumulate more in organisms living in close contact with the sediments (Baumard et al.

1998). Vives et al. (2004) found no correlation between PAH content in sediments and fish

liver and found that lake site was the most statistically significant factor of variability in PAH

concentrations in fish liver. The accumulation of PAH is also found to be controlled by the

biotransformation capacities of the organism in question (D'adamo et al. 1997), and by the

PAH concentration of the pray they feed on (Baumard et al. 1998). Fish age and sex was

found to have no significant effect on PAH concentration in fish liver (Vives et al. 2004).

PAHs accumulation and how persistent the PAHs are in the environment is also

controlled by the bioavailability of the PAHs compound, LMW PAHs are more readily

degraded by bacteria and fungi in soil (Morelli et al. 2013). HMW PAHs on the other hand is

more persistent because of their low bioavailability and strong adsorption onto the soil

organic matter (Morelli et al. 2013). There are many factors that control bioavailability of

PAHs in the environment some of them are PAH hydrophobicity, sediment organic carbon

content, sediment soot carbon content, and PAH source (Thorsen et al. 2004).

Biomagnification of PAHs through the food chain has been shown to occur to some

degree (e.g. from annelids to fish) but the greater capacity of higher organisms to metabolize

PAHs reduces the efficiency of the transfer (Douben 2003). Although some primary

consumers and detritivores may accumulate high levels of PAHs predators usually contain

low levels (Douben 2003). Invertebrates have slow metabolism that is unable to detoxify

PAHs in the way that vertebrates can, this can lead to more accumulation of PAHs (D'adamo

9

et al. 1997). D'adamo et al. (1997) suggest that mussel (Mytilus galloprovincialis) is a good

bioindicator of hydrocarbons in the environment because of it’s ability to bioaccumulate.

PAHs are also found to accumulate in plant tissue, Kipopoulou et al. (1999) found that

the mixture of PAHs in inner vegetable tissues was very similar to the mixture of PAHs in the

air vapor, they then suggest that gaseous deposition is the principle pathway for the

accumulation of PAHs.

Biodegradation and mechanisms for PAHs removal

PAHs are degraded by photodegradation, biodegradation by microorganisms and metabolism

in higher biota. While the latter is less important for the overall fate, it is crucial in terms of

effects through the formation of carcinogenic metabolites (Douben 2003). Biodegradation and

mechanism of detoxification and removal of PAH in organisms have been widely studied and

there has been some excitement around the possibility of removing PAH pollution from

contaminated soil with bioremediation. In this chapter I will give a short introduction to

biodegradation of PAHs, cytochrome P450 and Ah-receptor, and bioremediation methods.

Biodegradation of PAHs

Biodegradation of PAHs is the process in which PAHs are transformed as a result of

biological activity. The most important mechanism for PAH biodegradation is metabolic

dissimilation, which can cause the complete degradation to biomass, CO2, and H2O (Douben

2003). Many different species of bacteria, fungi, yeasts, and algae are known to degrade

PAHs (Douben 2003). Bacteria are generally assumed to be the most important group of soil

microorganisms involved in the (natural) biodegradation of PAHs in soils and sediments

(In:Douben 2003). Fungi may play a significant role in PAH degradation in the top soil

(Cerniglia et al. 1992). PAH degradation by yeast, cyanobacteria and algae is assumed to be

of no or little significance for the fate of PAHs in soil (Douben 2003).

Figure 4 shows the different pathways of PAHs degradation by microbial catabolism,

studies have shown that the pathway of degradation are similar for most PAHs but there is a

difference in the degradation rates of PAHs (Douben 2003). It is suggested that LMW PAHs

have a more rapid biodegradation rate then HMW PAHs in soil, or biodegradation rate

decreases with increased number of rings (Douben 2003; Wilson & Jones 1993).

10

Figure 4: Pathway for microbial catabolism of polycyclic aromatic hydrocarbons (Cerniglia 1992).

Cytochrome P450 and the Ah-receptor

The hemoprotein cytochrome P450 (CYP) exist in many forms that have contrasting yet

overlapping substrate specifies, and some forms of CYP are readily inducible (Walker et al.

2012). The appearance of a lipophilic xenobiotic inside the body can trigger the synthesis of

more CYP, leading to more rapid biotransformation of xenobiotics (Walker et al. 2012). This

is normally protective and helps an organism to eliminate the xenobiotic that caused the

induction, but in some cases the chemical causing induction is not metabolized by the induced

CYP (Walker et al. 2012).

Although oxidation by CYP in most cases causes detoxification, there are some

important exceptions. PAHs such as benzo(a)pyrene and aflatoxin B are converted into

epoxides that are strongly electrophilic and can bind to DNA (Walker et al. 2012).

Cytochrome P450 1A1 (CYP1A1) and cytochrome P4501B1 (CYP1B1) are two enzymes that

can generate active metabolites such as epoxides as a result of metabolizing PAHs (Shimada

& Fujii�Kuriyama 2004). Substrates of this kind frequently interact with aryl hydrocarbon

(Ah) receptor and can cause induction of CYP1A1 and CYP1B1, this can result in some

11

potentially toxic molecules can promote their own activation (Shimada & Fujii�Kuriyama

2004; Walker et al. 2012).

Bioremediation

As an effect of deposition of organic pollutants in soil, a lot of effort has gone into

remediation and bioremediation of soil. Bioremediation is the use of micro-organism

metabolism to break down hazardous organic material to harmless compounds, and is used for

reclaiming land contaminated by organic pollutants (Wilson & Jones 1993). A review by

Wilson and Jones (1993) found that bioremediation is found to be most successful for

removal of LMW PAHs (3 or fewer aromatic rings). One method that has good potential for

bioremediation is degradation of PAHs by fungi, this method has been widely studied and is

very effective for LMW PAHs (Morelli et al. 2013). Bioremediation of PAHs contaminated

soil can be a great tool for reclaiming land that are severally contaminated by PAHs, the

methods that have been studied seems to be quite effective on LMW PAH (Morelli et al.

2013).

Toxicity of PAHs

Several of the PAHs have long been recognized as having the potential to cause cancer in a

wide variety of vertebrate species, including humans, as well as some invertebrates (CCME

(Canadian Council of Ministers of the Environment) 2010). Not all PAHs are of the same

toxicity, the structure of the particle and the substitute groups determine harmful properties of

PAHs (Skupinska et al. 2004). Studies have shown that some PAHs compounds have both

carcinogenic and mutagenic (Douben 2003; Reynaud & Deschaux 2006), and immunotoxic

(Grundy et al. 1996; Reynaud & Deschaux 2006) properties. This has lead to that the effects

and properties of PAHs have become widely studied, and that some PAHs have made it on

the list of priority pollutants for the US and EU (Vives et al. 2004). In this chapter I will give

a short introduction to the carcinogenic, mutagenic, and immunotoxic effects of PAHs.

Carcinogenic and mutagenic

A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in

causing cancer (Campbell et al. 2008; Hine & Martin 2008). A mutagen is a physical or

chemical agent that changes the genetic material, usually DNA, of an organism and thus

increases the frequency of mutations above the natural background level (Campbell et al.

2008). Many mutations can cause cancer therefore mutagens are also likely to be carcinogens.

PAHs present in the environment are not active and unable to cause carcinogenesis, it is only

12

after entering an organism PAHs become metabolically transformed into carcinogenic forms

(Skupinska et al. 2004). Metabolic activation of PAH to DNA adducts is considered as a

crucial event in chemical carcinogenesis, involving covalent binding between the chemical

carcinogen and the DNA (In:Douben 2003). Different pathways of metabolic activation to

DNA adducts have been proposed for the PAHs, and benzo(a)pyrene have become a model

compound in carcinogenic studies (Douben 2003).

Figure 5 shows the chemical structures, physical and toxicological characteristics of 8

PAHs, the PAH compound that has been shown to be most carcinogenic for humans is

benzo(a)pyrene (IARC 2010; Klima- og forurensningsdirektoratet 2011). Benzo(a)pyrene

found in coal tar with the formula C20H12 and the main source of benzo(a)pyrene is residential

wood burning and industry (Klima- og forurensningsdirektoratet 2011). Its metabolites are

mutagenic and highly carcinogenic, and it is listed as a Group 1 carcinogen by the IARC

(IARC 2013).

Figure 5: Chemical structures, physical and toxicological characteristics of poly cyclicaromatic hydrocarbons. The symbols are: (DA) DNA adducts, (SCE) sister chromatid exchange, (CA) chromosomal aberrations, (Ames) Salmonella lyphimurium reversion assay, (UDS) unscheduled DNA synthesis, (-) not genotoxic. (Cerniglia 1992).

13

Immunotoxic

Immunotoxicity is defined as adverse effects on the functioning of the immune system that

result from exposure to chemical substances (Veraldi et al. 2006). Altered immune function

may lead to the increased incidence or severity of infectious diseases or cancer, since the

immune systems ability to respond adequately to invading agents is suppressed (Reynaud et

al. 2008; Veraldi et al. 2006). PAHs can have an effect on the immune system of organisms

because in animals biotransformation and the immune system is not totally independent, and

there exists many functional interrelationships between these two systems (Reynaud et al.

2008). In a study on PAHs effects on mussels (Mytilus edulis), Grundy et al. (1996) found

that PAHs inhibit phagocytosis and damage lysosomes. Grundy et al. (1996) hypothesize that

PAHs is directly toxic to lysosomes and as a possible consequents of this lysosome damage

will be immune impairment in mussels leading to reduced resistance to infectious diseases.

Effects of PAHs on fish (Literature review)

PAH pollution in fish have been widely studied because it is a good indicator of how much

PAH pollution that is biologically available in the environment of the fish. Fish metabolize

PAHs rapidly to intermediates that can either bind to the liver, DNA or form conjugates for

ultimate transfer to the bile (Vives et al. 2004). This is the main reason that the bile of the fish

is analyzed when looking for PAHs (Bakke & Håvardstun 2012), and the rapid metabolism

PAHs is the main reason PAHs does not bioaccumulate in fish (D'adamo et al. 1997). In this

chapter I will give a short introduction to the effects PAHs can have on fish in general.

Biochemical effects

There has been reported that PAHs have biochemical effects on fish. Biochemical effects that

have occasionally been reported are changes in hormones, energy reserves and serum

enzymes, but most observations in the environment have been on the induction of CYP

(Payne et al. 2003). As mentioned above, CYP1A1 and CYP1B1 could generate active

metabolites such as epoxides as a result of metabolizing PAHs (Shimada & Fujii�Kuriyama

2004). The self-induction of CYP is important in an ecotoxicological perspective, there is a

lot of literature associating CYP induction with the production of damaging free radicals and

adducts, which are important in mutagenic and carcinogenic processes (cf. Payne et al. 2003).

Genetic effects

“Damage to genetic material can theoretically lead not just to carcinogenesis and other

pathological effects in animals living now, but also produce genetic diseases in future

14

generations” (Payne et al. 2003). Damage to gametic DNA is of special importance, since

effects could potentially be transmitted between generations (Payne et al. 2003). Studies on

the induction of mutations or heritability by pollutant-induced mutations are difficult, but

there are some studies that are starting to appear pointing to the potential for PAHs to induce

mutations in fish and possibly heritability (Payne et al. 2003). Payne et al. (2003) concludes

that there is a lot of evidence from field and laboratory studies that have indicate that PAHs

are a significant risk factor for genetic toxicity in fish, most studies focus on the formation of

DNA adducts.

Immunological effects

There are few studies dealing with the immunotoxicity in fish from mixtures of PAHs or

individual PAHs (Payne et al. 2003). Reynaud and Deschaux (2006) found that the immune

system of fish is very sensitive to PAH pollution and that these pollutants affect both non-

specific and specific immunity. However, the effects that Reynaud and Deschaux (2006)

observed depend on the type of PAH, the route of administration, the concentration used, and

the species studied. A review by Reynaud et al. (2008) investigated the relationship of

biotransformation and the immune system, it is suggested that these two systems are not

totally independent as mentioned above. CYP and the Ah-receptor is suggested to be one

mechanism that can interact with the immune system, because the immune system works at a

physiological level it is suggested that many biotransformation mechanism can interact with

the immune system (Reynaud et al. 2008).

Reproductive and developmental effects

There have been some studies on the reproductive effects of PAHs on fish. “Reproductive

toxicity is one of the most important types of toxicity because of its potential for producing

adverse effects at a population level” (Payne et al. 2003). Long-term chronic toxicity and

reproductive studies are rather difficult to do, therefore experimental evidence is lacking

about the importance of PAHs to cause reproductive effects in fish (Payne et al. 2003). Payne

et al. (2003) also suggest that PAHs have potential for effects on growth and development,

with developing organisms usually displaying a greater sensitivity to chemicals than adults.

Payne et al. (2003) concludes that experimental data on this subject is limited, but there is

indication that development may be affected in larval and juvenile fish upon exposure to very

low levels of PAH.

15

Behavioral effect

Behavior alterations seems to generally received little attention in aquatic ecotoxicology but

alteration of behavior may be an important environmental consideration for fish in some

circumstances (Payne et al. 2003). Negative effects might include susceptibility to predation,

alteration of homing behavior or avoidance of feeding areas (Payne et al. 2003). Sediment

contaminated with relatively high levels of PAHs is probably is the most important factor that

have the potential to affect fish behavior (Payne et al. 2003).

16

Discussion In this paper I have tried to give a brief introduction to PAHs, I have explained its general

properties, emission sources, fate in the environment, biodegradation and toxicity. I have also

given a short review of the effects that PAHs have on fish. The goal of this paper as stated in

the introduction was to collect information about PAHs and explain why PAHs are such

important environmental pollutant. There are many reasons why PAHs are dangerous

environmental pollutant, and I will try summarize the different aspects here.

The emissions of anthropogenic PAHs have been reduced the last year as explained

above, this reduction has been traced back to modernization of aluminum smelter in Norway

(Klima- og forurensningsdirektoratet 2011). When comparing emissions from Norway

(Figure 1 & 2) and Europe (Figure 3) there is a significant reduction in emissions for both

Norway and Europe. But in Norway industry seems to be a more significant source then in

Europe, where in Europe commercial, institutional and households are the most significant

source. Why this is the case I cannot answer in this paper because it would be speculation, a

more thorough examination of the raw data is needed.

The physiochemical properties of PAHs as mentioned above make them very

persistent in the environment. The biodegradation pathways of the different PAHs are shown

to be very similar for LMW and HMW PAHs, but their biodegradation rates in soil were

found to differ. Generally the first-order degradation kinetics are observed and the

degradation rate is found to decrease with an increasing number of rings (Douben 2003;

Wilson & Jones 1993). This suggests that HMW PAHs are more persistent because of their

low bioavailability. This has also been found for bioremediation method; methods that use

fungi found that fungi were very effective for bioremediation of LMW PAHs but the methods

was not effective for HMW PAHs (Morelli et al. 2013). The persistence of PAHs makes it

easy for PAH to accumulate in the environment and in organisms that are unable to

metabolize them, and this makes PAHs very problematic environmental pollutants.

PAHs are not carcinogenic and mutagenic by itself, it can be transformed into a

carcinogens by metabolic transformation (Skupinska et al. 2004). This suggests that what is

making PAHs toxic is biotransformation in our own bodies. These biotransformation

mechanisms like CYP as explained above in most cases causes detoxification, but there are

important exceptions where PAHs such as benzo(a)pyrene are converted into epoxides that

was mentioned above. This makes PAHs potentially very toxic to animals and makes it a very

17

dangerous environmental pollutant. More research is needed on how PAHs can induce CYP

and how PAHs and their metabolites can interact with the Ah receptor.

PAHs have many different effects on fish you have biochemical, immunotoxic,

reproductive, developmental and behavioral effects. These 5 groups have a lot of different

types of effects on fish, and most of those effects you will probably also find in other animals.

Some of these groups are lack a lot of studies, and more effort and attention should be given

to the study of reproductive, developmental and behavioral effects of PAHs. There are

important factors that can lead to dramatic and long-term effects on fish. e.g. a very negative

and dramatic reproductive effect can have the potential to make entire fish populations to go

extinct.

Conclusion PAHs are persistent organic pollutant that can bioaccumulate in soil, vegetation and

organisms (especially lower invertebrates) and can have very toxic effects on animals and

humans. I conclude that PAHs are very dangerous environmental pollutant, and more research

is needed on how PAHs behave in the environment and the different effects of PAHs on

organisms.

18

Literature

Bakke, T. & Håvardstun, J. (2012). Revidert risikovurdering av propelloppvirvling av sedimenter ved Hydro Sunndals kaiområde, 978-82-577-6040-3. Oslo: NIVA. 46 s. : ill. pp.

Baumard, P., Budzinski, H., Garrigues, P., Sorbe, J. C., Burgeot, T. & Bellocq, J. (1998). Concentrations of PAHs (polycyclic aromatic hydrocarbons) in various marine organisms in relation to those in sediments and to trophic level. Marine Pollution Bulletin, 36 (12): 951-960.

Campbell, N., Reece, J., Urry, L., Cain, M., Wasserman, S., Minorsky, P. & Jackson, R. (2008). Biology. 8th. London: Persons International.

CCME (Canadian Council of Ministers of the Environment). (2010). Canadian Soil Quality Guidelines for Carcinogenic and Other Polycyclic Aromatic Hydrocarbons (Environmental and Human Health Effects). Scientific Criteria Document (revised). 216 pp.

Cerniglia, C. E. (1992). Biodegradation of polycyclic aromatic hydrocarbons. Biodegradation, 3 (2): 351-368.

Cerniglia, C. E., Sutherland, J. B., Crow, S. A. & Winkelmann, G. (1992). Fungal metabolism of aromatic hydrocarbons. In Microbial degradation of natural products., pp. 193-217.

D'adamo, R., Pelosi, S., Trotta, P. & Sansone, G. (1997). Bioaccumulation and biomagnification of polycyclic aromatic hydrocarbons in aquatic organisms. Marine Chemistry, 56 (1): 45-49.

Douben, P. E. (2003). PAHs: an ecotoxicological perspective: Wiley. Dreyer, A., Blodau, C., Turunen, J. & Radke, M. (2005). The spatial distribution of PAH

depositions to peatlands of Eastern Canada. Atmospheric environment, 39 (20): 3725-3733.

EMEP. (2012). Persistent Organic Pollutants in the Environment. Status Report 3/2012. 87 pp.

European Environment Agency. (2012). European Union emission inventory report 1990–2010 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP). EEA Technical report No 8/2012. 148 pp.

Grundy, M. M., Ratcliffe, N. A. & Moore, M. N. (1996). Immune inhibition in marine mussels by polycyclic aromatic hydrocarbons. Marine Environmental Research, 42 (1): 187-190.

Hine, R. S. & Martin, E. (2008). A dictionary of biology. Oxford: Oxford University Press. 717 s. : ill. pp.

IARC. (2010). Some Non-heterocyclic Polycyclic Aromatic Hydrocarbons and Some Related Exposures. In vol. 92 IARC Monographs on the Evaluation of Carcinogenic Risks to Humans p. 868. Lyon, France: International Agency for Research on Cancer.

IARC. (2013). Agents classified by the IARC monographs, Volumes 1–107. Available at: http://monographs.iarc.fr/ENG/Classification/index.php (accessed: 21.04).

Kipopoulou, A., Manoli, E. & Samara, C. (1999). Bioconcentration of polycyclic aromatic hydrocarbons in vegetables grown in an industrial area. Environmental pollution, 106 (3): 369-380.

Klima- og forurensningsdirektoratet. (2011). PAH: MIljøstatus.no. Available at: http://www.miljostatus.no/Tema/Kjemikalier/Noen-farlige-kjemikalier/PAH/ (accessed: 20.04).

19

Morelli, I., Saparrat, M., Panno, M., Coppotelli, B. & Arrambari, A. (2013). Bioremediation of PAH-Contaminated Soil by Fungi. In Goltapeh, E. M., Danesh, Y. R. & Varma, A. (eds) Soil Biology, vol. 32 Fungi as Bioremediators, pp. 159-179: Springer Berlin Heidelberg.

Payne, J. F., Mathieu, A. & Collier, T. K. (2003). Ecotoxicological Studies Focusing on Marine and Freshwater Fish. In Douben, P. E. (ed.) PAHs: an ecotoxicological perspective: Wiley.

Reynaud, S. & Deschaux, P. (2006). The effects of polycyclic aromatic hydrocarbons on the immune system of fish: A review. Aquatic Toxicology, 77 (2): 229-238.

Reynaud, S., Raveton, M. & Ravanel, P. (2008). Interactions between immune and biotransformation systems in fish: A review. Aquatic Toxicology, 87 (3): 139-145.

Shimada, T. & Fujii�Kuriyama, Y. (2004). Metabolic activation of polycyclic aromatic hydrocarbons to carcinogens by cytochromes P450 1A1 and1B1. Cancer science, 95 (1): 1-6.

Skupinska, K., Misiewicz, I. & Kasprzycka-Guttman, T. (2004). Polycyclic aromatic hydrocarbons: physicochemical properties, environmental appearance and impact on living organisms.

Thorsen, W. A., Cope, W. G. & Shea, D. (2004). Bioavailability of PAHs: Effects of soot carbon and PAH source. Environmental science & technology, 38 (7): 2029-2037.

Veraldi, A., Costantini, A. S., Bolejack, V., Miligi, L., Vineis, P. & van Loveren, H. (2006). Immunotoxic effects of chemicals: A matrix for occupational and environmental epidemiological studies. American journal of industrial medicine, 49 (12): 1046-1055.

Vives, I., Grimalt, J. O., Fernandez, P. & Rosseland, B. (2004). Polycyclic aromatic hydrocarbons in fish from remote and high mountain lakes in Europe and Greenland. Science of the total environment, 324 (1): 67-77.

Walker, C. H., Sibly, R. M., Hopkin, S. P. & Peakall, D. B. (2012). Principles of ecotoxicology. Boca Raton, Fla.: CRC Press. XXV, 360 s. : ill. pp.

Wilson, S. C. & Jones, K. C. (1993). Bioremediation of soil contaminated with polynuclear aromatic hydrocarbons (PAHs): a review. Environmental pollution, 81 (3): 229-249.