7/28/2019 Pollutants Types

1/24

1

Arturo A. Keller

ESM 222

Classification of Pollutants

2 Arturo A. Keller

Priority Pollutants

Amount Produced/ReleasedPersistenceBioaccumulationToxicityOther Effects

7/28/2019 Pollutants Types

2/24

3 Arturo A. Keller

Amount Produced or

ReleasedSome pollutants are produced in largeamounts but only released accidentally(e.g. chlorinated solvents, benzene)Others are released intentionally in largeamounts (e.g. pesticides)Some very toxic pollutants are onlyproduced in very small amounts (e.g.dioxins)

4 Arturo A. Keller

Persistence

Resistance to transformation in theenvironment either chemical or biologicalPersistent chemicals can migrate widelyMeasured as residence time or as half-life Chlorinated/halogenated compounds aretypically persistent (e.g. DDT, PCBs, CFCs)

Rate of degradation depends on environmentalconditions

7/28/2019 Pollutants Types

3/24

5 Arturo A. Keller

Bioaccumulation

Uptake of pollutant by organismsDepends on hydrophobicity (i.e. water-hating), persistence and toxicity of pollutantConcentration may increase more than100,000 times from water to fishConcentration is biomagnified going upthe food chain

6 Arturo A. Keller

Bioaccumulation

Sediments

Sea water

Fresh water

Sewage

Plankton

Aquatic invertebratesFishBirdsBird eggs

Marine Mammals

10 -7 10 -5 10 -3 10 -1 10 1 10 3 10 5

Concentration of total PCBs in ppm (mg/kg)

(from Pearson, 1982)

7/28/2019 Pollutants Types

4/24

7 Arturo A. Keller

Toxicity

Acute toxicity: concentration which kills 50% of a given

population (usually determined in lab) expressed as Lethal Dose to 50%: LD 50 ,

in units of mg chemical/kg body weight also depends on exposure

8 Arturo A. Keller

Toxicity

Chronic toxicity Sub-lethal tests adverse effects: cease to feed, grow more

slowly, unable to reproduce or just abnormalbehavior

typically occurs at dosages 10 to 100 timessmaller than acute toxicity; more difficult,controversial & expensive to test

7/28/2019 Pollutants Types

5/24

9 Arturo A. Keller

Toxicology

Solvents as a general class Usually have high vapor pressures, so they

form vapors: major intake route is throughinhalation

Toxicity usually expressed as LD 50 in termsof air concentration

Most solvents depress the central nervoussystem => anesthetic effect

10 Arturo A. Keller

Toxicology

Solvents CNS depression symptoms:

dizziness, confusionheadachesloss of coordination

convulsionscomadeath

7/28/2019 Pollutants Types

6/24

11 Arturo A. Keller

Toxicity

Genotoxicity Carcinogenic or mutagenic New tests are constantly developed, but

given low dosage and exposure, it is alwaysdifficult to determine increased risk

Short-term, high dosage test vs. long-term,low dosage in real life

Additional environmental factors alsogenotoxic

12 Arturo A. Keller

Other Effects

Ability to influence large-scale biogeochemistry(e.g. CFCs, acid rain)

Alter availability of nutrients or other neededorganic chemicalsOdor (e.g. sulfur compounds, MTBE)Color (e.g. organic dyes)Foaming (e.g. detergents)Interfere with visibility (e.g. SO 2 particulates)

7/28/2019 Pollutants Types

7/24

13 Arturo A. Keller

Classification of Pollutants

What is the best criteria forclassification? Physical properties Chemical properties Chemical structure Effect on the environment

Organic vs. Inorganic

14 Arturo A. Keller

Classification of Pollutants

Organic Chemicals Hydrocarbons Halogenated hydrocarbons Oxygenated hydrocarbons Nitrogen compounds

Sulfur compounds Phosphorus compounds

7/28/2019 Pollutants Types

8/24

15 Arturo A. Keller

Classification of Pollutants

Inorganic pollutants Arsenic Lead Copper Cadmium Mercury Chromium

Chlorine Cyanide Nitrate Ammonia

16 Arturo A. Keller

Hydrocarbons

Formed by biogenic processes: microbes,vegetation, animalsContamination from oil spills, refineries,leaking USTs, fuel transport and useOnly slightly soluble in water, veryhydrophobic: Hexane about 10 mg/L = 10 g/m 3Linear hydrocarbons are easily degraded bymicrobes; branched are resistant

7/28/2019 Pollutants Types

9/24

17 Arturo A. Keller

Hydrocarbons

Hydrocarbons with double or triple bonds(alkenes, alkynes) are highly reactive: short lives in the environment

Aromatics: Fairly toxic (e.g. benzene, xylenes, ethylbenzene,

toluene) Considerably more soluble in water

(e.g. benzene = 1780 g/m3

)major concern for water supplies.

18 Arturo A. Keller

Hydrocarbons

Fusion of benzene rings producespolycyclic aromatic hydrocarbons (PAHs)= polynuclear aromatic hydrocarbons(PNAs) Many are considered potential carcinogens.

benzo(a)pyrene

7/28/2019 Pollutants Types

10/24

19 Arturo A. Keller

Hydrocarbons

Effects on Living Organisms Physical

smotheringreduced lightinability to swim, fly, etcfur or feathers cannot function properly

Habitatdecrease dissolved oxygendecrease food availability

20 Arturo A. Keller

Hydrocarbons

Effects on Living Organisms Toxicity of most hydrocarbons is usually low

at low concentrations, given theirbiodegradability

may affect internal organ functions (liver, kidney,etc) if ingested

PAH cause cancerous and non-canceroustumors in fish, reptiles, amphibians andmammals in lab studies

7/28/2019 Pollutants Types

11/24

21 Arturo A. Keller

Toxicology of Alkanes

Highly lipophilic so they target fatty tissueCNS depressantsDirect aspiration causes chemical pneumonitisConcentrated gasoline vapors cause cardiacarrhytmiaTypical half-life of hexane in body is 2h 10 days to remove hexane from fatty tissue

Some metabolites of hexane may cause otherfunctional disturbances

22 Arturo A. Keller

Toxicology of AromaticHydrocarbons

Benzene and derivativesPrincipal exposure route is by inhalation30 to 80% absorbed by circulating bloodConcentrates in fatDestroys bone marrow and affects blood cellsConsidered a carcinogen (lungs, leukemia)

Acute exposure depresses CNS (3000 to 5000ppm)Higher concentrations cause death

7/28/2019 Pollutants Types

12/24

23 Arturo A. Keller

Halogenated Hydrocarbons

Halogens: Chlorine, Bromine, Iodine,Fluorine halogens are highly reactive as gases form very stable organic compounds

less flammablemore persistent in environment

less hydrophobic => more soluble inwater

24 Arturo A. Keller

Toxicology of ChlorinatedHydrocarbons

Chloroform (CHCl 3)discontinued use as anesthetic in medicine due toeffect on liver and heartused in lacquers, plastics and refrigerantmanufactureexposure routes: inhalation, ingestion, dermalsuspected animal carcinogen (liver, renal)present in drinking water as a byproduct of chlorination to disinfect water

7/28/2019 Pollutants Types

13/24

25 Arturo A. Keller

Toxicology of Chlorinated

HydrocarbonsCarbon Tetrachloride (CCl 4)

anesthetic and antihelmintic agentused in dry cleaning and degreasingclassified as carcinogenacute exposure depresses CNSchronic exposure affects liver and kidney

26 Arturo A. Keller

Trichloroethylene (TCE) (CHCl=CCl 2)dry cleaning, degreasing, solventused to extract caffeine from coffeediscontinued use as anesthetic in medicineclassified as carcinogendirect exposure irritates eyes, nose, throatacute exposure affects CNSchronic exposure affects liver and kidneys

Toxicology of ChlorinatedHydrocarbons

7/28/2019 Pollutants Types

14/24

27 Arturo A. Keller

Tetrachloroethylene (PCE) (CCl 2=CCl2)dry cleaning, degreasing, grain fumigantexposure routes: inhalation and dermalabsorptiondistributes through body, stored in fatsclassified as carcinogenacute exposure affects CNS

Toxicology of Chlorinated

Hydrocarbons

28 Arturo A. Keller

Halogenated Hydrocarbons

Chlorinated aromatics biologically active, i.e. they interfere

with normal processes persistent useful as pesticides and disinfectants

Pentachlorophenol Chlorobenzenes, dichlorobenzenes

7/28/2019 Pollutants Types

15/24

29 Arturo A. Keller

Halogenated Hydrocarbons

Polychlorinated biphenyls (PCBs)Large family (209) of compounds

Very stable, used as electrical insulator fluids inpower transformers until ~ 20 yearsfluorescent light until 1970shydraulic fluids, brake fluids, heat transfer,plastizicers, lubricants, flame retardants

base for pesticides

30 Arturo A. Keller

Halogenated Hydrocarbons

PCBspersistent and significant bioaccumulationlow acute toxicityincident in Japan in 1968 brought them attention(1291 individuals affected by contaminated riceoil)

from 1979 on, total ban on use of PCBs except incompletely enclosed systemsriver sediments are a major reservoir (e.g. UpperHudson, St. Lawrence)

7/28/2019 Pollutants Types

16/24

31 Arturo A. Keller

Halogenated Hydrocarbons

Fluorinated and chlorofluorinatedhydrocarbons are extremely stable best example is TEFLON, a fluorinated polymer

with extreme stability, temperature resistance andhydrophobicity (usually not a pollutant)

CFCs are used as refrigerants due to their stability.Their persistence in the lower atmosphere allowstransport to stratosphere where they interact withozone formation. Half-lives of decades in theatmosphere .

32 Arturo A. Keller

Oxygenated Compounds

Alcohols (OH group) very widely used industrially usually water soluble usually highly degradable in the

environment

only an issue if spilled in large quantities large-chain alcohols (e.g. octanol) can besolvent for hydrophobic and hydrophilicorganics.

7/28/2019 Pollutants Types

17/24

33 Arturo A. Keller

Toxicology of Alcohols

Rapidly absorbed through lungs,gastrointestinal tract and skinDistributed through body tissues and fluidsCNS depressants at high doses (e.g. ethanol !)Methanol => formaldehyde => formic acid,which affect optic nerve, causing blindnessEthanol in large doses or repeated ingestioncauses hepatic or cardiac toxicity

34 Arturo A. Keller

Oxygenated Compounds

Phenols aromatics with alcohol group may disrupt biological processes chlorinated phenols are particularly toxic

used in wood preservation (e.g. telephonepoles) which has led to widespreadcontamination of certain sites

Biodegradablemay be used to stimulate bioremediation

7/28/2019 Pollutants Types

18/24

35 Arturo A. Keller

Oxygenated Compounds

Esters, Ethers, Ketones & Aldehydes usually only a problem in atmospheric

pollution, where they contribute to ozoneformation in urban areas

fairly reactive in aquatic systems may be formed by incomplete combustion

industrial use is relatively small carcinogenicity of aldehydes

36 Arturo A. Keller

Oxygenated Compounds

Organic acids usually quite reactive, so they are not of

major environmental concern

Dioxins and dibenzofurans form by oxidation/combustion of

chlorinated organics at high temperatures possibly the most toxic organics

7/28/2019 Pollutants Types

19/24

37 Arturo A. Keller

Nitrogenated organics

Amines, amino acids, proteins, etc. most are formed in biological processes can be quite toxic, but typically produced only in

small quantities biologically active but degradable some are formed during incomplete combustion

of fossil fuels (e.g. nitro PNAs) explosives manufacture and use (TNT)

38 Arturo A. Keller

Pesticides

Organochlorines DDT, Methoxychlor, Aldrin, EndosulfanOrganophosphates Malathion, Parathion, Diazinon,

Chlorpyrifos, Glyphosate (Roundup)

Carbamate Esters Carbofuran, AldicarbPhenoxy Esters 2,4-D, Silvex, 2,4,5-T

7/28/2019 Pollutants Types

20/24

39 Arturo A. Keller

Pesticides

Also grouped by intended function:InsecticidesHerbicidesFungicidesRodenticides

40 Arturo A. Keller

Inorganic Pollutants

Metals most are essential for biological activity

macronutrients: calcium, magnesium, iron,potassium, sodiummicronutrients: chromium, cobalt, copper,manganese, nickel, selenium, zinc

toxic in large doses mercury and lead form organometallic compounds

which disrupt normal biological processes

7/28/2019 Pollutants Types

21/24

41 Arturo A. Keller

Inorganic Pollutants

Natural releases via volcanoesHuman sources:

miningfuel combustion, cement productionfoundriesrefuse incinerationindustrial products, processes and waste

pesticides or fertilizers

42 Arturo A. Keller

Toxicology of Metals

Arsenic Substitutes for phosphate, disrupting

metabolic processes (e.g. in ADP-ATP energycycle of cells)

Cadmium

Affects renal, pulmonary, skeletal, testicularand nervous systems Disrupts zinc-dependent enzymes

7/28/2019 Pollutants Types

22/24

43 Arturo A. Keller

Toxicology of Metals

Lead Inhibits hemoglobin synthesis => anemia Substitutes for Calcium, reducing cellular

functions (e.g. ATP production) Stored in bones, where it becomes a life-

long source of lead to the blood Organic lead compounds affect brain

function May cause lung cancer

44 Arturo A. Keller

Toxicology of Metals

7/28/2019 Pollutants Types

23/24

45 Arturo A. Keller

Toxicology of Metals

Mercury Mercury vapors and organomercury enter

central nervous system Affects brain and nerve cells Sensory disturbance, reduced field vision

and ataxia

Impairment of speech, hearing and mentalfunctions

46 Arturo A. Keller

Toxicology of Metals

7/28/2019 Pollutants Types

24/24

47 Arturo A. Keller

Inorganic Pollutants

Nitrate (NO -3) good fertilizer, toxic at high concentrations easily leaches out to rivers, ponds, lakes cause of lake eutrophication

Ammonia (NH 3) good fertilizer very toxic even at low concentrations

easily oxidized to nitrate in presence of O 2 in high concentrations affects pH of soil

48 Arturo A. Keller

Biological Pollutants

Human pathogens

Medical Waste

Animal pathogens