C2003 – ENVIRONMENTAL CHEMISTRY Course goals: After this course, students should be able to:  understand problems related to pollution of the environment from natural and anthropogenic sources Understand the pollutants Understand the environment (and how this relates to the pollutants) Understand how we measure pollutants in the environment Understand the ways that we use environmental data – risk assessment and environmental policy This is pretty ambitious...so let’s break it down a bit... Course overview Understand the pollutants Understand the environment (and how this relates to the pollutants) Understand how we measure pollutants in the environment Understand the ways that we use environmental data – toxicology Week 1 Week 3 Week 2 & 4 Week 5 What is pollution?  Presence of a substance in an environmental system having a harmful effect  The substance = pollutant or contaminant Pollutants Natural Radon Heavy metals Anthropogenic PCBs Pesticides Flame retardants Just a few examples... Pollution depends on context...  Many are have both natural and anthropogenic sources (e.g., PAHs, metals...)  Only a pollutant when unwanted adverse effect:  E.g., ozone, pesticides... http://spaceplace.nasa.gov/greenhouse/en/ Environmental chemistry  Environmental chemistry is the study of chemical processes occurring in the environment which are impacted by human activities.  Can be local scale, e.g., urban air pollutants or toxic substances from a chemical waste site -or Can be global scale, e.g., long-range pollution transport, global warming Why is chemistry important to understand pollution? A chemical’s structure dictates that compound’s “personality,” - provides a systematic basis to understand and predict chemical behavior in the environment - With and understanding of the properties and behaviour of chemicals, we can better understand what the impact of humans is on the global environment Schwarzenbach et al. Environmental Organic Chemistry Types of pollutants  Many classes and methods for classification exist – we will consider a few of the major types of pollutants:  Volatile organic compounds  Airborne particulate matter  Persistent organic pollutants  Polycyclic aromatic hydrocarbons  Heavy metals  etc. Particulate matter (PM)  Solid and liquid particles suspended in air  Naturally occurring and anthropogenic  Natural sources:  Salt particles from sea spray, pollen, moulds, bacteria, debris from plants and animals, soil particles entrained by wind, etc.  Anthropogenic sources:  Industrial processes, open burning, vehicles, agriculture, mining, etc.  PM is not a specific chemical, but a mixture of particles with different origin, composition, size, shape, etc.  Important itself (e.g., has negative health effects) and as a carrier for other atmospheric pollutants Particulate matter PM sizes and examples From Finlayson-Pitts and Pitts, 2000, Chemistry of the Upper and Lower Atmosphere Particulate matter Van Donkelaar et al. EHP 2015 Particulate matter – excluding dust and sea spray Particulate matter - exposure European Environment Agency: "Particulate matter is the air pollutant that poses the greatest health risk to people in Europe." European Guideline – annual average PM10 should not exceed 40 μg/m3 Semivolatile organic compounds (SVOCs)  Not a firm grouping  Generally determined by vapour pressure  typically between ~1 and 10-10 Pa Why are they important? • Can distribute in multiple media (gas-phase air, particle-phase air, soil, water, plants, lipids, floor dust, window films…) • Many are persistent, lipophilic, bioaccumulative • Many chemicals of concern are in this group. SVOCs in the environment Canadian Environmental Protection Act (ec.gc.ca) Examples of SVOCs  Pesticides  Industrial chemicals  By-products  Additives in consumer products Well-known SVOCs Cl Cl Cl Cl Cl Cl ClCl Cl Cl Cl O Cl ClCl Cl Cl Cl Cl Cl Cl DDT (p,p’-DDT) HCH (γ-HCH/Lindane) Dioxin (2,3,7,8-PCDD) PCB (PCB 118) Pesticides By-product Industrial chemical POPs / PBT  Many SVOCs are classified as “persistent organic pollutants” (POPs) or “persistent, bioaccumulative and toxic” (PBT)  3 key terms to understand:  Persistence  Bioaccumulation  Toxicity Environmental Persistence  The length of time a chemical remains in environmental system or media  Governed by the rates at which the compound is removed from the system by biological and chemical processes, such as environmental transport, biodegradation, hydrolysis, atmospheric reactions  Measured as the half-life of the substance in the medium  A chemical is considered persistent if it has a half-life of:  >2 days in air  ~2-6 months or more in water, sediment or soil Bioaccumulation  The accumulation of a chemical in tissues of an organism through any route, including respiration, ingestion, or direct contact with the contaminated environment i.e. Rate of chemical uptake >> rate of chemical loss  If a chemical is “bioaccumulative” this means that the concentration of the chemical in the tissues of an organism can be significantly higher (e.g., several orders of magnitude) than the concentration of the chemical in the surrounding environment  Measured by bioaccumulation factor (BAF)  BAF > ~1000 means a chemical is considered “bioaccumulative” BAF = Conc. on contaminant in organism Conc. on contaminant in ambient environment Toxicity  A measure of the amount which a substance can cause harm to an organism  Related to the dose of a chemical received by and organism  moderately toxic substance can cause harm if an organism receives a higher dose  Highly toxic substance can cause harm at low doses Examples of SVOCs  Pesticides  Industrial chemicals  By-products  Additives in consumer products Pesticides – intentionally toxic! Chemicals designed to kill, reduce or repel pests Insecticides Herbicides Fungicides Rodenticides Insects Weeds Moulds Rodents How pesticides enter the environment Langenbach. “Persistence and bioaccumulation of Persistent Organic Pollutants” 2013 Global pesticide use Insecticide Herbicide Fungicide 2.5 million tonnes per year (Alavanja, 2009) From FAO Statistical Yearbook, UN 2013 Most common pesticides  In 1960s...  Today... Organochlorine pesticides  OCPs = organochlorine pesticides  What are the OCPs?  DDT  Hexachlorobenzene (HCB)  Pentachlorobenzene (PeCB)  Hexachlorocyclohexanes (multiple isomers)  Heptachlor/heptachlor epoxide  Aldrin/dieldrin/endrin  Chlordane (multiple isomers)  Endosulfan  Mirex  … Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Mirex HCHs α β γ Cl Cl Cl Cl Cl PeCB Cl Cl Cl Cl Cl Cl HCB Endosulfan Aldrin Dieldrin Endrin cis-chlordane trans-chlordane trans-nonachlor heptachlor Chlorinated molecules – highly stable – therefore environmentally persistent Case study 2: DDT  DDT – dichlorodiphenyl trichloroethane ClCl Cl Cl p,p'-DDD ClCl Cl Cl p,p'-DDE ClCl Cl Cl Cl p,p'-DDT ClCl Cl ClCl o,p'-DDT Degradation products/metabolites are often also considered: Chemical DDT vs. Technical DDT  Chemical DDT – dichlorodiphenyltrichloroethane, generally p,p’-DDT – the isomer with insecticidal properties  Technical DDT – mixture of p,p’-DDT, o,p’-DDT, DDE and DDD  DDE and DDD are impurities in technical mixture and breakdown products of DDT ClCl Cl Cl Cl p,p'-DDT p,p’-DDT: 63-79% o,p’-DDT: 8-21% p,p’-DDD: 0-4% o,p’-DDD: 0-0.05% Active ingredient Impurities DDT – a brief history 1872 – DDT was first synthesized by Austrian chemistry student 1939 – insecticidal properties discovered WW2– global use of DDT against typhus, malaria 1945 – DDT available to public 1940s, 1950s – WHO and country-specific programs targeting elimination of malaria – successful in Europe and North America, and large reduction in cases in India, southeast Asia DDT – a brief history 1959 - More than 36 million kg of DDT was sprayed over the US 1961 - DDT use reaches its peak. 1962 - Rachel Carson’s book Silent Spring blamed environmental destruction on DDT. “The toxicity of DDT to Certain Forms of Aquatic Life” 1945 1946: 1947: 1940s, 1950s – Gradual increase in number of scientific studies identifying negative effects of DDT on wildlife DDT – a brief history 1972 – DDT ban in USA and Canada 1974 – DDT ban in Czechoslovakia 1970s, 1980s –ban on DDT in many countries 2001 – Stockholm Convention on POPs – DDT is banned with limited exceptions for malaria control Currently From Czech National Implementation Plan for Stockholm Convention Where is DDT still used? Legally – for malaria control:  Botswana, Eritrea, Ethiopia, India, Madagascar, Marshall Islands, Mauritius, Morocco, Mozambique, Namibia, Senegal, South Africa, Swaziland, Uganda, Venezuela, Yemen, Zambia  Illegal use continues in limited locations? DDT – What are the concerns? Persistence, toxicity, long-range transport and bioaccumulation/biomagnification! What are typical trends in DDTs? SumDDT compounds in ice core from Mt. Everest glacier (Wang et al., Atmospheric Environment, 2008) DDT compounds in precipitation from North America, 1995-2005 (Sun et al., Environmental Science and Technology, 2006) What are typical trends in DDTs? Time  Conc.(ng/g) SumDDT compounds in herring fish from Sweden from 1977-1995 A. Polder , C. Thomsen , G. Lindström , K.B. Løken , J.U. Skaare Levels and temporal trends of chlorinated pesticides, polychlorinated biphenyls and brominated flame retardants in individual human breast milk samples from Northern and Southern Norway Chemosphere, Volume 73, Issue 1, 2008, 14 - 23 Time trend of levels of HCB, sum-DDTs and sum-PCBs in breast milk DDT – remaining questions? Replacements for OCPs  Current pesticide use is 2.5 million tonnes per year (Alavanja, 2009)  OCPs are generally no longer used:  ~5000 tonnes DDT (produced in China, India and North Korea)1 – 0.2% of global use  Only 6 countries reporting use of other OCPs (Ecuador, Honduras, Iran, Lesotho, Madagascar, Tajikistan, Ukraine) - ~2300 tonnes total in 20112  Replacement pesticides should have lower persistence and bioaccumulative potential 1 Van den Berg, EHP 2009; 2 FAO Statistics (faostat.fao.org); Currently used pesticides  Glyphosate (“Round-up”)  Herbicide  In use since 1970s  Most widely use chemical pesticide in world  ~650000 tonnes per year (>30% of world pesticide market)  Atrazine  Herbicide  banned in EU but high use in many other countries  70000 tonnes per year  Chlopyrifos  Most widely used insecticide  170000 tonnes per year (~7% of world pesticide market) Comparing 2 insecticides: Chlorpyrifos vs. DDT DDT  Vapour pressure: 0.0003 Pa  Solubility: 0.025 mg/L  Half-life in soil: 2-15 yrs  Overall environmental half-life: 1-5 yrs  Characteristic travel distance: 255 km Chlorpyrifos  Vapour pressure: 0.001 Pa  Solubility: 2 mg/L  Half-life in soil: 60-120 days  Overall environmental half-life: 30 days  Characteristic travel distance: 62 km Data from Pesticide Information Profiles, Extoxnet, Cornell University; and Mackay et al. 2014 Comparing 2 insecticides: Chlorpyrifos vs. DDT DDT  ASTDR oral reference dose: 0.0005 mg/kg/day  LD50: ~100-1000 mg/kg  Not acutely toxic to birds, but acutely toxic to aquatic organisms  Evidence for reproductive, mutagenic and teratogenic effects in humans Chlorpyrifos  US EPA oral reference dose: 0.003 mg/kg/day  LD50: ~80-300 mg/kg  Toxic to birds (LD50 8- 100 mg/kg)  Not identified as reproductive toxic, or teratogenic, mutagenic Data from Pesticide Information Profiles, Extoxnet, Cornell University Any questions about pesticides? Examples of SVOCs  Pesticides  Industrial chemicals  By-products  Additives in consumer products Polychlorinated biphenyls - PCBs Use •Discovery of compound, of useful properties •Spread of use Concern •Increasing number of scientific studies identifying concern •Push-back from industry •Weight of evidence Consequences •Regulation •Phase-out •Environmental problem -High chemical and physical stability, even at high temperatures Desirable property! - Industrially produced in 10 countries for a range of uses - Can also occur as a by-product of some industrial processes, esp. cement production and pulp and paper industries - First detected in environment in Swedish fish in 1966, many more reports followed - Concerns about environmental persistence and bioaccumulation - Production and new use banned by many countries in 1970s, 1980s - Banned under Stockholm Convention But...PCBs remain in use in old building equipment, electrical equipment, etc. PCBs – chemical structure Cl Cl Cl Cl Cl • 209 possible congeners • 1 to 10 chlorines • only 130 were used commercially • Classified based on degree of chlorination 2,3',4,4',5-Pentachlorobiphenyl PCB 118 Indicator PCBs – 7 congeners: PCB 28 PCB 52 PCB 101 PCB 118 PCB 153 PCB 138 PCB 180 PCBs – health effects  Acute vs. chronic effects  Associated with cancer, liver function, skin effects at occupational exposure levels  Prenatal exposure slows development in children  Some evidence of link with breast cancer  Dioxin-like PCBs What were PCBs used for?  Transformers and capacitors  Other electrical equipment including voltage regulators, switches, reclosers, bushings, and electromagnets  Oil used in motors and hydraulic systems  Old electrical devices or appliances containing PCB capacitors  Fluorescent light ballasts  Cable insulation  Thermal insulation material including fiberglass, felt, foam, and cork  Adhesives and tapes  Oil-based paint  Caulking  Plastics  Carbonless copy paper  Floor finish Sanexen Environmental Services PCB production over 1 million tonnes globally PCB use in North America – in tonnes Hafner and Hites, ES&T, 2003 Why are PCBs still in use?  Because they are so useful for their purpose!  Where they were used was not well-documented  Challenges with removing all PCBs from use – current legislation only requires PCBs to be removed at >50 ppm CN Tower, Toronto, Canada CN Tower Built 1972 Had transformer containing PCBs Transformer is located in viewing area, 342 m high Had to be cut apart by hand Too big to be taken down elevator Packed piece-by-piece into steel drums, removed by elevator Any questions about PCBs? Examples of SVOCs  Pesticides  Industrial chemicals By-products  Additives in consumer products By-products  By-products of industrial processes, combustion  Unintentionally produced during industrial processes, fossil fuel combustion for heating, transportation, etc.  Examples:  Polycyclic aromatic hydrocarbons  Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans Dioxins and furans Dioxins in the news... Dioxins and furans – chemical structures O ClCl Cl Cl Cl Cl O Cl ClCl Cl Cl ClCl O Cl ClCl Cl Cl Cl Cl Cl O Cl ClCl Cl ClCl O Cl ClCl Cl ClCl O Cl ClCl Cl Cl Cl O Cl ClCl Cl Cl O Cl ClCl Cl O O Cl Cl ClCl Cl ClCl Cl O O Cl Cl ClCl Cl ClCl O O Cl Cl ClCl Cl Cl O O Cl Cl ClCl Cl Cl O O Cl Cl ClCl Cl Cl O O Cl Cl ClCl Cl DioxinsFurans Sources of PCDD/Fs  Unintentionally produced  During inefficient/incomplete combustion, especially waste burning  By-product from chemicals manufacturing  Major sources are: waste incineration, automobile emissions, metal industries, burning of peat, coal, wood Spatial patterns of PCDD/Fs  Higher concentrations closer to sources, in highly developed, industrialized areas  Concentrations patterns in air, soil, sediment and biota mirror each other  Trends on a large scale – globally – and small scale - locally Local scale – PCDD/Fs in soil around an incinerator Goovaerts et al. 2008 Bignert et al. 2007 Regional scale – PCDD/Fs in fish from the coast of Sweden Polycyclic Aromatic Hydrocarbons (PAHs)  By-products of combustion or fossil fuel processing  Composed of two or more aromatic rings  Many possible structures, but typically 3 to 6 rings PAH Sources Zhang and Tao, Atmospheric Env. 2009 PAHs over the past 300 years Gabrieli et al. 2010 Any questions about PCDD/Fs or PAHs? Examples of SVOCs  Pesticides  Industrial chemicals  By-products  Additives in consumer products Additives to consumer products  Flame retardants  Plasticizers Flame retardants – organic or inorganic chemicals added to consumer products (furniture, electrical appliances, electronics) to suppress/delay/prevent the spread of fire Plasticizers – additive chemicals that increase the flexibility, softness, fluidity of a material. Largely used in plastics. Flame retardants 69 • To slow the spread of flames • Organic or inorganic • Wide range of applications (furniture, electronics, industrial/workplace textiles and protective equipment, vehicles) • Required by fire safety regulations http://www.jptarpaulins.com/ PBDEs  Polybrominated diphenyl ethers  Flame retardants  Classified by either technical mixture or congener group  Confusing!! E.g., penta-BDE can refer to either the technical mixture called “Penta” or could refer to a PBDE with 5 bromines  Commercial mixtures sometimes distinguished as “c- penta” PBDE naming - congeners BDE-99 Pentabromodiphenyl ether BDE-47 Tetrabromodiphenyl ether BDE-153 Hexabromodiphenyl ether BDE-154 Hexabromodiphenyl ether BDE-100 Pentabromodiphenyl ether BDE-183 Heptabromodiphenyl ether BDE-209 Decabromodiphenyl ether BDE-28 Tribromodiphenyl ether Polybrominated Diphenyl Ethers: Uses Penta Textiles, PUF, paint, household plastic products, automotive parts banned under Stockholm Convention Octa ABS plastic for computers, casings, circuit boards, small appliances banned under Stockholm Convention Deca Electrical & electronic equipment, casings for TVs, computers, textile backings (e.g., carpets) Still in use in some areas, phased out in Europe, North America Human health concerns for PBDEs  Thyroid active agents  Neurological impairments  Maturation  Delay in puberty  Developmental neurotoxicity  Impaired spontaneous motor behaviour, nonhabituation behaviour  Learning & memory  Worsen with age Review: Birnbaum & Staskal 2004 EHP 112:9-17. Estimated Historical Consumption Of Penta BDE in Europe Prevedouros et al. 2004 Environ Sci Technol 38:3224-3231 Estimated Consumption Of BDEs in North America Abbasi et al. 2015 Environ Sci Technol How to PBDEs get from furniture into the environment?  Volatilization  Abrasion, physical breakdown of the furniture  Direct partitioning to dust Global distributions of PCBs and PBDEs From Pozo et al. 2006 Hites 2004 Environmental Science & Technology Temporal trends of PBDEs San Francisco Bay sediment and water: Sutton et al. 2014, Environmental Science & Technology Replacement of banned compounds Flame retardancy standards remain Need for new compounds to meet flame retardancy standards “Novel” brominated and chlorinated flame retardants Unknown properties, effects ???? 2000-2015: Banning/ phasing out of PBDEs “Novel” flame retardants - NFRs – replacements for PBDEs Br Br Br BrBr Br Br Br BrBr O CH3 CH3 O Br Br Br Br Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl O O BrBr Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br CH3 Br Br Br Br Br CH3 Br Br Br Br HBB DDC-CO DBDPE BTBPE DBE-DBCHEH-TBB PBEB PBT Phosphate- based flame retardants in consumer products Stapleton et al. Environmental Science and Technology, 2009 Chemicals to know  DDT  PCBs  PCDD/Fs  PAHs  PBDEs What to know… ABOUT EACH COMPOUND:  Source/use of the compound  Industrial? Emission by-product?  Status  Is the chemical still in use? Where is it legal/illegal?  Where do we find the chemical?  In the environment? In humans? How are humans exposed?