Human Health & The Environment MIDTERM

What is the Environment

The environment refers to the surrounding conditions, including the air, water, soil, and ecosystems, that influence the health and well-being of living organisms. It encompasses both natural and built environments and plays a crucial role in human health.

Gene-Environment Interaction

The interplay between genetic makeup and environmental factors that influence an individual's health outcomes.

• models of gene-environment interaction

  • genetic makeup increases exposure to an environmental risk factor

  • genetic makeup increases susceptibility to an environmental risk factor

Types of Hazards

• chemical hazard

• biological hazard

• physical hazard

• social or behavioural hazards

• genetic traits

chemical hazard

chemicals in air, soil, and food

biological hazard

bacteria, viruses, parasites, allergens, animals, such as bees and poisonous snakes

physical hazard

housing, urban development, land use, transportation are environmental health hazards

• natural fires, tornados, volcanic eruptions, and earthquakes are not environmental health hazards (they are natural disasters or natural hazards)

social or behavioural hazard

poor diet, smoking, drugs, drinking, poverty are not environmental health hazards (but the chemicals in tobacco smoke - are secondhand smoke 

genetic traits

health risks associated with the chromosomal defect that causes Down syndrome

Core Concerns of Environmental Health

• focus on chemical, biological, physical hazards

• interactions with genetic traits with social/behavioural stressors

• emphasis on anthropogenic hazards

• much more than just pollution

• as branch of public health, the field of environment health takes a population perspective

Case Study 1: London Smog, 1952

• a man guides a London bus through thick fog with a flaming torch during the 1952 Great Smog

• the smog was the result of coal-burning

Case Study 2: Indonesian Fires, 1997

• smoke over Lake Toba, Sumatra, Indonesia, photographed by the Space Shuttle Atlantis

• smoke from fires set to clear land for agriculture in Indonesia at one time in 1997 blanketed an area larger than the continental United States

• fire damage classification of the 1997 - 1998 fires in East Kalimantan, Indonesia, based on ERS-SAR images

Health Effects of Outdoor Air Pollution

the effects depend on the dose or concentration

• asthma

• chronic bronchitis

• pulmonary emphysema

Seven Common Outdoor Air Pollutants 

• Particulate matter

• Carbon monoxide 

• Nitrogen oxides 

• Sulphur oxides 

• VOC (Volatile Organic Compounds) 

• Lead

• ground level ozone

Particulate matter

• Particles found in the air (dust, soot, smoke, and liquid droplets)

• Vehicles, factories, construction sites, tilled fields, stone crashing, and all kinds of burning

• Some formed in the air

• Serious health effects

• Big and small

• Particulates classified by size

  • PM10 — respirable

  • PM2.5 — “fine” (mostly from combustion)

  • Ultrafine particulates

Carbon Monoxide

• Odourless, colourless gas

• Incomplete burning of carbon-containing fuels

• Heaters, woodstoves, gas stoves, fireplaces, water heaters, automobile exhaust, and tobacco smoke

• Bigger problem for indoor air pollution

• 1000 people die each year in US as result of CO poisoning (indoor air)

• Sometimes confused with flu or food poisoning

• Fetuses, infants, elderly and people with heart and respiratory illnesses are at high risk for adverse health effects

Health Effects of Carbon Monoxide

• Interferes with the delivery of oxygen in the blood to the rest of the body

• Worsen cardiovascular conditions 

• Fatigue 

• Headache 

• Weakness 

• Confusion 

• Disorientation, loss of coordination 

• Nausea, Dizziness, Death

Prevention

• Never leave a car engine running in a shed or garage or in any enclosed space

• Proper selection, installation, and maintenance of appliances

• Correct use of appliances

• Good ventilation

• Use CO detectors

Nitrogen Oxides (NOx)

• Formed in any type of combustion process

• Involved in formation of ground-level ozone

• Forms nitrate particles, and acid aerosols

• Contribute in formation of acid rain

• Transported over long distances

Sulphur Oxides (SOx)

• Burning of coal and oil, extraction of metals from ore

• SO2 dissolves in water vapour to form acids

• Acids react with other gases and particles and form sulphates

• Transported over long distances

• Respiratory illnesses, aggravates existing heart and lung diseases

VOC (Volatile Organic Compounds)

• Variety of organic compounds used as solvent in industry, automobiles

• Hydrocarbons (HC): methane, butane, propane

• Some produce photochemical smog (will be explained later)

Lead (Pb)

• Metal 

• Vehicles and industrial sources 

• Leaded gasoline 

• Deposit on soil and water 

• Children accidentally can eat soil 

• Particularly affects young children

• Lead is neurotoxicant

Ozone (O3)

• VOC + NOx + Heat + Sunlight = Ozone

• Summertime pollutant, time of the day, seasonal, climate 

• Good in stratosphere 

• Bad on the ground 

• Transported on long distances 

• Lung damage (small airways) 

• Shortness of breath, chest tightness, coughing and nausea

• Irritate and damaged eyes, nose, sinuses and throat 

• Problem for people who exercise outdoors during the concentration picks

smog

• Smoke + fog = Smog (first used in 1905 in England)

• Sulphurous smog- London type of smog or industrial smog

• Photochemical smog - L.A. type of smog or brown air

Airborne Hazards

• Outdoor air pollution

• Indoor air pollution

  • Contains 2-5 times higher concentration of hazardous pollutants than outdoor air

  • Buildings more airtight to conserve energy, inadequate ventilation

  • People spend about 90% of their time indoors

  • Children, pregnant women, elderly, and people with chronic illnesses are more sensitive

Sources of Pollutants

• Building materials and furnishing 

• Asbestos insulation 

• Wet or damp carpet 

• Furniture made of certain pressed wood products 

• Cleaning products and air fresheners

• Personal care and hobbies

• Pesticides 

• Cooking 

• Bathing 

• Heating (combustion of oil, coal, wood) 

• Radon 

• Smoking

• Outdoor pollution

Unhealthy Construction Materials and Sick Buildings

• “Sick building syndrome” 

  • Nonspecific symptoms experienced by occupants of a building

• “Sick building” designation 

  • A building whose occupants experience such symptoms 

• Building-related illness 

  • Specific diagnosable illnesses, linked to specific feature of building

Health Effects of Indoor Air Pollution

• Hard to detect by our senses 

• Symptoms are similar, need years to develop 

• Headaches, tiredness, dizziness, nausea, itchy nose, scratchy throat 

• Asthma 

• Cancer

Six Common Indoor Air Pollutants

• Asbestos 

• Formaldehyde 

• Mold and Moisture 

• Secondhand Smoke 

• Radon Gas 

• Air Dust

Asbestos

• Group of six different fibrous minerals 

• Have separable, long, strong and flexible heating resistant fibers

Asbestos in the Environment

• Do not evaporate into air or dissolve in water, do not break down 

• Fibers and particles may remain suspended in the air and carried long distances 

• Not able to move through soil

How might you be exposed to asbestos

• In industrialized countries, nearly everyone has asbestos fibres in their lungs

  • some risk of cancer

• People working in some industries 

• People living near these industries 

• During demolition work and remodelling 

• From drinking water (natural sources or asbestos containing cement pipes)

Health Effects of Asbestos

• Affects the lungs and the membrane that surrounds the lungs

• Asbestosis- Scar-like tissue, not in general public

  • difficulty breathing

  • often cough

  • heart enlargement 

  • lead to disability and death

• Plaques in the pleural membranes 

• Lung cancer, mesothelioma 

• Increase risk of getting other types of cancer (stomach, esophagus, pancreas, kidney) 

• Risk increases with smoking 

• Not related with birth defects 

• Low levels can be measured in urine, faces, and mucus

Formaldehyde

• Volatile organic compound (VOC), naturally occurring gas, colourless, and strong smell

• Becomes a gas at normal room temperature

• Also released by burning wood and natural gas, by automobile and by cigarettes

• Glue or adhesives in pressed wood products (particleboards, MDF, plywood)

• Preservatives in some paints and cosmetics

• Coatings that provide permanent press quality to fabrics and draperies

• Finish used to coat paper products

• Certain insulation materials

Health Effects of Formaldehyde

• Allergic reactions 

  • Watery eyes, burning sensation in the eyes, nose and throat 

  • Skin rashes

• Nausea 

• Coughing 

• Chest tightness 

• Asthmatic reactions 

• Cancer 

• Some people very sensitive

Mold and Moisture

• Need moisture, does not need standing water, just requires high relative air humidity

  • Bathrooms and kitchens 

  • Gym areas 

  • Locker rooms 

  • Leaky roof areas 

  • Damp basements 

  • On or within wood, paper, carpet and foods

Mold Health Effects

• Major source of indoor allergens

• Trigger asthma

• Produce Toxins

• Produce Irritants

Mold and Moisture

• The way to control indoor mold growth is to control moisture (maintaining the relative humidity between 30-60%)

• Often undiscovered 

• Produce tiny spores 

• Discoloration and odour problems

Second-Hand Smoke 

• Contain 4000 compounds (CO and Formaldehyde), 40 are carcinogens

• A non-smoker exposed to secondhand smoke has a 25% increased chance of developing lung cancer

• EPA estimates that each year 3 000 lung cancer deaths among nonsmoking adults in US

• Health Canada estimates that more than 300 non-smokers die from lung cancer each year because of such exposure

• Environmental tobacco smoke (secondhand smoke):

  • Adults: heart disease, heart attack, lung cancer, hearing loss, eyes, nose and throat irritation 

  • Children: SIDS, asthma, pneumonia, bronchitis, ear infection and hearing loss

• Smoking is on the rise in less developed countries

  • More than 8 million people projected to die from smoking-related causes by 2030

Radon Gas

• Colourless, odourless, tasteless 

• Naturally occurring 

• Radioactive decay of uranium 

• From soil and rock into basements and lower floors indoor air 

• Dissolved in groundwater, pumped into wells and then into homes  

• In construction building blocks

Radon Gas in Buildings

• Natural hazards in some regions

  • Begins a series of rapid breakdowns 

  • Radon and some progeny are alpha emitters; lung cancer risk

  • Often simple to detect and remediate

Air Dust

• Heating and cooling -forced air system

• Dust particles 

• Pollen or other debris 

• Duct Cleaning Service Providers

Liquid Natural Capital

• the earth is a water planet 

• water covers 71% of the Earth’s surface 

• mostly salty water

• no species can live without water

• Sculpting the earth's surface 

• Moderating climate 

• Removing and diluting wastes and pollutants

World Problems

• quantity of water

• quality of water

• Some areas have lots of water but the largest rivers are far from agricultural and population centers

• Lots of precipitation arrives during a short period but cannot be collected and stored

• Use about 54 % of the world's reliable runoff of surface water and could be using 70-90% by 2030

• Withdrawal- total amount of water removed from a river, lake or aquifer for any purpose

  • Some may be returned to the source for reuse but not all

  • Some lakes and rivers shrink

Hydrological Poverty

• One out of six people do not have regular access to clean water

• Diarrheal deaths kill over 2 million children annually

Water and Your Health

• Drinking water

  • Annual reports on local drinking water quality 

  • Naturally pure water & distilled water

  • Natural content of minerals in water

  • Surface water - In urban areas

    • rivers 

    • lakes 

  • Groundwater- In rural areas

    • wells 

    • springs

• Swimming water

Quality Water

• Water pH

• Hardness

• Colour 

• Turbidity 

• Taste 

• Odor

• Microbes and chemicals 

Contaminants in Drinking Water

• Microbes (1)

• Radionuclides (2)

• Inorganic Contaminants (3)

  • Arsenic

  • Fluoride

  • Lead 

  • Nitrates (fertilizers - nonpoint sources)

• Industrial Organic Contaminants (4)

  • pesticides and herbicides (nonpoint sources)

  • volatile organic compounds (VOC)

• Disinfection by-products (5)

Microbes (1)

• Fecal Coliform and E. coli bacteria – contamination with human and animal wastes, diarrhea, cramps, nausea, headaches, renal failure, coagulation disorders

• Salmonella typhi – typhoid fever (high fever, abdominal pain, constipation)

• Shigella sp.- more severe abdominal cramping with blood and mucus in the stool

• Vibrio cholerae – life-threatening, rice-water stools

• Norwalk viruses, enteroviruses, adenoviruses - diarrheal illness

• Hepatitis A- liver inflammation

• Cryptosporidium – parasite that enters lakes and rivers through sewage and animal wastes

• Giardia lamblia - enters lakes and rivers through sewage and animal wastes, diarrhea, vomiting, cramps

Radionuclides (2)

• Alpha emitters

• Beta/photon emitters 

• Combined Radium 226/228 

• Radon gas 

• Radium

• Damage to DNA, Increased risk of getting cancer

Radon

• a colourless and odorless gas

• Produced by the radioactive decay of uranium, in particular Uranium-238 with a half-life of 4.5 billion years, and other radioactive minerals

• Radon decays radioactive isotopes Polonium-218 and Polonium-214 which also produces alpha particles that if breathed or swallowed can cause several types of cancer

• Uranium is found in several types of minerals associated with granites, metamorphic gneiss, and sedimentary rock derived from weathering and erosion of granite

• Radon can build up in the basement of a home constructed on soils with high radon levels or if the basement walls are built of granite

Radium

• Radium Hot Springs, located within the boundaries of Kootenay National Park, BC as it appeared shortly after opening (early 1900s)

Inorganic Contaminants (3). —— Arsenic

• High concentrations of arsenic are poisonous and lower concentrations can cause skin cancer and melanosis (dark pigmentation of the skin)

• After many years of drinking lower levels, the possibility of skin damage, problems with the circulatory system

• Arsenic occurs in more than 200 different minerals that are relatively rare and usually in low concentrations

• Arsenic dissolves very readily in groundwater and can move long distances from its source

• When many sources combine, arsenic can concentrate in toxic level in the groundwater

Inorganic Contaminants (3). —— Fluoride

• Fluoride concentration greater than 1.5 milligrams per liter can become potentially harmful

• Small amounts added to drinking water to promote dental health

• Exposure to high concentrations of fluoride can cause dental fluorosis and skeletal fluorosis (bone disease)

• Fluoride is found in the common mineral fluorite and in certain types of micas and clay minerals

• The highest concentrations of fluoride are found in regions of volcanic activity

• Unlike arsenic ions, the highly reactive fluoride ions in the groundwater tend to form chemical compounds within short distances of its source, therefore, high levels of fluoride are typically found close to its source material

Inorganic Contaminants (3). —— Lead

• Lead pipes are banned 

• Anemia 

• Brain, kidneys and nervous system damage 

• Appetite loss 

• Abdominal pain 

• Constipation 

• Fatigue 

• Sleeplessness

• Irritability 

• Headache 

• Miscarriages and stillbirths

• Most serious for young children (intellectual development, behavior, size and hearing of infants)

Inorganic Contaminants (3). —— Nitrates

• Inhibits the red blood cell’s ability to transfer oxygen

• Methemoglobinemia – oxygen starvation, cyanosis (bluish discoloration of the skin and lips)

• Spontaneous abortion and neural tube defects

Industrial Contaminants (4) —— Pesticides and Herbicides

• Chlorinated Hydrocarbons 

  • DDT, Chlordane, Lindane 

  • Persistent, bioaccumulating, biomagnifying 

  • Not mammal-toxic

  • Very negative ecological effects

• Organophosphates and Carbamates 

  • Round-up (glyphosate) (grasses) 

  • Metolachlor, Alachlor (weeds) 

  • Triazines 2,4-D; 2,4,5-T (many plants) 

  • Rapid decay, not persistent 

  • Not bioaccumulating and not biomagnifying

Industrial Contaminants (4) —— MTBE (Methil - Tert - Butyl Ether)

• Fuel additive, replace the use of lead as octane enhancer 

• Used to reduce carbon monoxide and ozone levels caused by auto emission 

• Leaking of underground tanks, to some extent from air deposition

Disinfection Byproducts (5)

• Formed when disinfectants react with naturally occurring organic and inorganic matter in water

  • Trihalomethanes – excess over many years cause liver, kidney, or central nervous system problems, increased risk of getting cancer

  • Haloacetic Acid – increased risk of getting cancer

  • Bromate – increased risk of getting cancer

  • Chlorite – children could experience nervous system effects, some people may experience anemia

Household-level Water Supply or Treatment

• Devices for home water treatment

• Point-of-use systems installed at tap (e.g., carbon filter at kitchen sink)

Bottled Water

• Expensive; often groundwater source; not likely to be fluoridated

• Regulated not as drinking water, but as packaged food

• Often disinfected using ozone or UV light (no residual effect needed)

Endocrine Disrupters

• Toxicology data mostly from animal studies, not much from human exposure

• Direct effects 

  • Bind to hormone receptors 

  • Alter the appearance of some genes 

  • Changes in the level of produced proteins

  • Indirect effects 

    • Altering hormone production 

    • Altering hormone transport 

    • Altering hormone metabolism

DES (diethylstilbesteol)

• Synthetic estrogen used by physicians to prevent spontaneous abortion (1948-1971)

• Administered for early pregnancy until 35 weeks

• > 1 million women took it between 1960-1970

• Daughters whose mothers took DES have increased incidents of :

  • Reproductive organ dysfunction 

  • Abnormal pregnancies 

  • Reduction in fertility 

  • Immune system disorders 

  • Carcinoma

Endocrine Disrupters - Health Implications

• Feminization of males 

• Change in sexual behaviour 

• Birth defects 

• Altered time to puberty 

• Cancer of mammary glands or testes 

• Thyroid dysfunction (example)

Endocrine Disrupters - Neurobehavioural Implications

• Prenatal and early postnatal exposures 

• PCBs (Polychlorinated biphenyls):

  • Impaired learning in nonhuman primates 

  • Delayed psychomotor development 

  • Distractibility 

  • Poor IQ tests

• Organophosphates 

  • Brain development

Case Study: Pesticides and Children

• Research supports the hypothesis that exposure to pesticides may affect the development of intelligence and motor skills of young children

• This study compared two groups of rural Yaqui Indian preschoolers in Mexico (1998), one frequently exposed to pesticides, the other rarely exposed to pesticides.

Chemical Body Burdens

• Quantity of chemicals accumulated in the body

  • Biomonitoring – “normal level”

    • Blood and fat analysis

    • Not stable over time

    • Not distributed homogeneously in a body

    • Not possible to detect if present in very low concentrations

Organochlorine Substances

• Dioxins 

• DDT

• Phthalate and Bisphenol A

Dioxins

• Dioxins have no commercial usefulness by themselves • Formed during

  • Formed during 

    • combustion processes such as waste incineration, forest fires and backyard trash burning 

    • manufacturing processes such as herbicide manufacture and paper manufacture

  • Group of chemical compounds with similar chemical structure 

  • One of the most toxic and most studied is 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD)

  • Accumulate in fatty tissue

  • Bioaccumulation/Biomagnification 

  • Very slowly removed from the body (POP-persistent organic pollutants) 

  • In food

  • At low levels- Effects of constant exposure to low levels is not known 

  • Focal point for ongoing research (the molecular and cellular mechanisms)

  • At high levels very toxic

    • cause cancer in laboratory animals and humans, mechanism is not known 

    • alter reproductive and developmental functions 

    • increased risk for heart disease and diabetes 

    • causes immunosuppression 

    • study in mice showed ability to cause birth defects

DDT (C14H9Cl5) —- (dichloro-diphenyl-trichloro-ethane)

• Agricultural pesticide

• Typhus- lice control

• Malaria - widely used for mosquito control for 20 years before persistence appreciated

• Travels long distances 

• Found in every corner of the globe 

• Global distillation, “Grasshopper effect” 

• Very persistent (POP) • Bioaccumulation/Biomagnification 

• Accumulates in fatty tissues of people and animals 

• DDT in breast milk

Human Health Effects

• Carcinogen – linked to breast cancer 

• Damage to reproductive system 

• Reduced reproductive success 

• Damage to the liver 

• Endocrine disruptor – mimicking estrogenic compounds in the body 

• Chronic long-term exposures affect nervous system

DDT Restrictions

• Banned in the US in 1972 except for public health emergencies. Small amounts were used until 1980. In 1991, the US exported 92 tons of DDT.

• In at least 26 countries, DDT is completely banned, and in 12 others it is severely restricted. In these latter cases, it is permitted for use by government agencies for special programs, usually involving vector control programs

• Total bans

  • Canada 1985 

  • Chile 1985 

  • Cuba 1970 

  • Liechtenstein 1986 

  • Korea 1986 

  • Poland 1976 

  • Singapore 1984 

  • Switzerland 1986

DDT

• Levels in humans dropped in the past thirty years

• Low levels of exposure still occurs (seafood, crops grown in contaminated soil, imported food)

• Targeted use for mosquito control in some less developed countries with high malaria rates is approved by WHO

Some countries which permit the import of DDT

• Bhutan 

• Guinea 

• Malaysia 

• Nepal 

• Sudan 

• Venezuela 

• Bolivia 

• Mauritius 

• Philippines 

• India 

• Tanzania 

• Vietnam 

• Ethiopia 

• Kenya 

• Mexico

•  Sri Lanka 

• Thailand

Phthalate and Bisphenol A

• Phthalate—chemicals used to make plastics plastic

• Bisphenol A (BPA) also used in production of plastics

• May move slowly into air or into contents of container

• Health effects of phthalates and bisphenol-A:

  • Endocrine disruptors 

  • Developmental effects in male lab animals and male infants (reduced anogenital distance) 

  • Emerging evidence of link to obesity in lab animals and people

Heavy Metals

• Metallic chemical element that has specific gravity usually more than 5g/mL

• Toxic in even low concentrations 

• Naturally occurring, extracted from the earth, in ore 

• Wide environmental dispersion 

• Tendency to accumulate in select tissues

Classification of Metals

• Class A: 

  • K, Na, Mg, Ca 

  • Macronutrients (essential for biological processes) 

  • Low toxicity

  • Class B:

    • Hg, Pb, Ti 

    • Nonessential elements 

    • Very toxic (form soluble organometallics)

  • Borderline: 

    • Cr, Cu, As, Co, Ni, Zn, Mn, Fe 

    • Almost all micronutrients

Mechanisms of Toxicity

• Blocking essential functional groups in proteins or enzymes; proteins can not carry anything

• Displace other metals (class B, borderline)

• Modifying the active conformation of biomolecules (class B)

Coping Mechanisms

• Resistance – species develop mechanisms not to uptake metal (example Pb)

• Tolerance – the capacity of a species to withstand high levels of metals

  • Internal detoxifying mechanisms

    • Binding to non sensitive compound structures 

    • Metabolic transformations to less toxic forms (methylation of As in marine biota)

  • Can develop multiple tolerance - Cu, Pb, Zn, Cd

Bioavailability of Metals

• Species of the metal-free ions (charged ions Zn+2 are more bioavailable than Zno ) 

• Neutral species may be bioavailable, important in complexes 

• pH of water/soil 

• Redox potential of solution

Routes of Exposure

• Inhalation (dust or PM, fume, gas) 

• Ingestion (soil, food, plants accumulate metals in roots) 

• Through the skin

• Mostly accumulate in the liver, bones, and kidneys 

• Damage the brain, kidney, and some carcinogens 

• Hard to diagnose (symptoms are weakness, headaches, and hypertension)

Mercury (HG)

• Metallic form - in batteries, dental amalgams, and thermometers 

• In industries, in different forms 

• Liquid in pure form - not significant hazard 

• When volatilize very toxic 

• Organic and Inorganic forms, both toxic 

• Bioaccumulation (tuna fish)

• “MAD HAT-MAKERS SYNDROME” 

• Tremor of the hands, excitability, memory loss, insomnia, and sometimes delirium 

• Sensitivity of fetal and infant nervous system to low levels of Hg (mental retardation, language, memory and neural problems if mother is exposed during the pregnancy)

What are the Wood Preservatives

• Chemicals that protect wood from rotting due to insects and microbial agents and on that way prolong age in service of wood products

• CCA-C (chromated-copper-arsenate)

• Content 

  • 47.5 % CrO3

  • 18.5% CuO

  • 34% As2O5

• Waterborne preservative

• Vacuum-Pressure Impregnation Treatment of Wood

• Retort

• Fixation process -chemical reaction of Cr, Cu and As salts with wood components

Production of CCA-Treated Wood

• 100% of residential lumber is treated with CCA before it is phased out

• 70% of all wood products is treated with CCA before it is phased out 

• It was important industry in North America before it is phased out in 2003 (annual gross sales in USA of around $3.91x10^9 )

Positive Side of CCA Wood Preservation

• Long efficacy: 50 years and more in ground contact; 

• Excellent results in marine use; 

• No odor to wood; 

• No problems with corrosion; 

• UV resistant; 

• Simple quality control; 

• Reasonable price; 

• Reduce needs for cutting forests

Environmental Concerns

• Leaching 

  • Soil 

    • ingestion, 

    • inhalation, 

    • plants, 

    • soil organisms, 

    • groundwater

  • Aquatic systems 

• Rub off on hands (ingestion)

Toxicity of CCA Components

• Form (speciation) of elements 

• Soil and water characteristics 

• Characteristics of organisms

Form (speciation) of Elements

• Cr (VI) exists as anions, more mobile and toxic than Cr (III) which exists as the cation; 

• As (III) more mobile and toxic than As (V) both are anions; organic form is less toxic than inorganic form; 

• Cu exists as cation;

Toxicity of CCA Components

• Soil characteristics 

  • pH 

  • Organic matter 

  • Texture (clay, silt, sand) 

  • Fe, Mn, Al oxides

• Soil as barrier against toxicity

Plants 

• Negative 

  • Combined Cr, Cu, and As (7000ppm) completely inhibited the growth of beans, carrots and tomatoes (Grant and Dobbs, 1977)

  • Carrots grown in soil with 1000ppm of Cr, Cu, and As (200ppm As), contained twice the recommended limit for As in food (Grant and Dobbs, 1977)

• Positive 

  • No influence of treated wood on growth and content of Cr, Cu and As in tomatoes (Jin and Preston, 1993), and grapes (Levi et. al, 1974)

Toxicity of As, Cu and Cr to Human (in general not just from CCA)

• As –accumulate in nails, hair and skin, most dangerous, carcinogen, linked to skin, bladder, lung, liver and kidney cancer as well as immunosuppression, cardiovascular disease and diabetes, at very low level can change hormone function;

• Cr – carcinogenic, linked to lung cancer, asthma, and ulcers;

• Cu -vomiting, diarrhea, stomach cramps, and nausea (drinking water), liver damage (very young children under high dose), not known to cause cancer or birth defects, and very toxic for aquatic environment.

Present Situation

• Wood scientists vs. environmental scientists

• CCA is phased out for residential use in Canada in Dec. 2003

• New wood preservatives are Cu-based

We can not escape radiation 

• Background radiation  —- natural radioactivity in the Earth and by cosmic rays from outer space 

  • Can not be controlled 

  • Manmade radiation —- electronic products 

    • X-ray machines 

    • X-ray diagnostic 

    • Television sets 

    • Microwave ovens 

    • Radar devices 

    • Lasers 

    • Can be controlled

Ionized Radiation

• How does ionized radiation cayse health effects? 

  • Radioactive material that decay spontaneously produce ionizing radiation

    • Strip away electrons from atoms (create charged ions) 

    • Breaks some chemical bonds

  • Alpha, beta, gamma particles, and x-rays (differ in the amount of energy they have)

Health Effects from Exposure to Radionuclides

• Stochastic health effects - Chronic

  • Long term, low level of exposure 

  • Increase levels of exposure make these effects more likely to occur but do not influence the type or severity of the effect

• Non-stochastic health effects - Acute

  • Short term, high level of exposure

  • Increase levels of exposure make these effects more severe

Stochastic Health Effects

• Changes in DNA —- mutations

  • Teratogenic (fetus most sensitive in 8-15 week of pregnancy, smaller head or brain size, poorly formed eyes, and mental retardation)

  • Genetic (passed from parent to child)

  • Cancer- uncontrolled growth of cells - Damage at the cellular or molecular level

Non-Stochastic Health Effects

• Radiation sickness 

  • Nausea, weakness, hair loss, skin burn or diminishing organ function, premature aging, and death

• Cancer —- uncotrolled growth of cells 

  • Damage at the cellular or molecular level

Carcinogenesis

• Cancer: a disease in which cells multiply without restraint

  • Tumor invades tissue of origin

  • Metastasis into other tissues

• Cancer results from an accumulation of mutations

  • Mutation: change to the DNA of a cell

• Key mutations in carcinogenesis

  • Increase the activity of genes that instruct the cell to divide (oncogenes); or 

  • Decrease the activity of genes that instruct the cell to stop dividing (tumor suppressor genes)

• Carcinogen: any agent that increases cancer risk at any stage in process

• Simple view of stages in carcinogenesis

  • Initiation — initial mutation in a cell

  • Promotion — initiated cell is stimulated to divide, becoming a benign tumor

  • Progression — mutations → cell division → malignant tumor

Chemical Properties of Radionuclides

• Organs can not distinguish between radioactive and nonradioactive forms of element

  • Radioactive iodine in the thyroid

  • Calcium, strontium -90 and radium -226 accumulate in bones

Nuclear Power Plant Accidents

• Three Mile Island, Pennsylvania, 1979

• Chernobyl, former Soviet Union, 1986

• Chernobyl accident had 10-20 times higher dose of exposure than Three Mile Island’s accident