Toxic Substances
no-observed effect levels (NOELs)
(NOELs) investigations into the relationship between levels of exposure and the observed human health effects led to the identification od NOELs and the establishment of adequate margins of safety for exposure.
Acute vs. chronic toxicity
* acute: lead poison manifests itself as abdominal pains; *chronic: lead poison provokes anemia and nervous system damage * there is no correlation and no connection between their relative potency; * a chemical that is acute exposure may be nontoxic chronically; * a chemical that is chronic exposure may be minimal acute toxicity
Polychlorinated Biphenyls (PCBS)
* discovery in 1964 Dr. Soren Jensen examining DDT in human fat and wildlife samples, found large amounts of PCBs (synthetic organic chemical); *first synthesized in 1929 trade name AROCHLOR *have been used in hydraulic fluids, adhesives, insulating tape, paints, caulk, sealants, and road coverings to control dust. *high boiling point, high solubility in fat but low solubility in water, low electrical conductivity, and high resistance to heat; *1973 FD established tolerance levels for PCBs in food, passage of Toxic Substances Control Act in 1976 and in 1977 US manufacturer of chemicals terminated PCB production. *1942 recommended max allowable conc in the workplace *1928-1977 - approx. 1.4 billon pounds of PCBs were produced in the US *500 million pounds of PCB have been dumped *2009 Superfund remediation is a 40 mile stretch of Upper Hudson River where GE dumped its toxic wastes decades ago.; GE has built a dewatering facility near the site to process the dredged materials, returning clean water to the river and sending the dried toxic sediment by train to a landfill in Texas.
Bisphenol A - (BPA) - Health Risk
* do not microwave any plastic food containers with the #7 on bottom *don't wash any plastic containers in the dishwasher *reduce personal use of canned foods *choose glass, ceramic, or stainless steel for hot foods or liquids *use only BPA free baby bottles and choose toys labeled BPA free
Asbestos
*6 silicate minerals (amosite, chrysotile, tremolite, actinolite, anthophyllite, and crocidolite); *results in death *China is worlds leading producer *found in brake linings, insulation, textiles, roofing paper, ironing board covers, caulking compounds, floor tiles, ***etc. * fibers remain trapped in lungs and cause cancer; (inhalation is main route) but can be exposed by mineral in drinking water. *1973 documentation EPA ban spray application of asbestos insulating and fireproofing materials; *31,000 primary and secondary schools across the nation were sprayed with this insulation and approx. 2-6 million children inhaling asbestos from 1946-1973; *1983 66% schools had not even inspected for asbestos so President REGAN signed a Asbestos Hazard Emergency Response Act (AHERA) requiring inspection.
Dose-Response Curve
*A type of graph used to describe the effect of exposure to a chemical or toxic substance upon an organism such as an experimental animal. *first part is horizontal (indication that low doses of toxic produce no ill effects) *second part is threshold which refers to the lowest dose at which a particular response may occur (increasing dosage is beginning to provoke adverse symptoms) *third part (flattens out after reaching maximum effect - death) *TWO TYPES OF CURVES: one for responses of an individual to a chemical and one for a population
Effects of Chemical Mixtures
*Additive *Synergism *Potentiation *Antagonism
Asbestos Related Disease
*Asbestosis - scarring of lung tissue *Lung cancer - leading cause of asbestos-related mortality; exposure increases risk 7 times; with cigarette smoking risk is 60 times greater *Mesothelioma - cancer of lung or stomach lining, asbestos is only known cause; invariably fatal generally within 2 years of diagnosis
Exposure - Skin (Dermal)
*Contact with skin, mucous membranes, or eyes by absorption (topical mode) *The skin is the body's largest organ consisting of many interconnected tissues covering an area of nearly 3,000 in.2 in the average adult. *Materials may pass through the skin by: **Absorption through hair follicles or sweat glands ***Esp. hydrophilic - soluble in H2O ***Lypophilic - fat soluble by passive diffusion **Breaks in the skin **Injections directly into the bloodstream **Arthropod bites or stings **High pressure steam or liquid
Exposure - Gastrointestinal Tract
*Gastrointestinal tract by ingestion (e.g., consumption of contaminated food or drink) *The gastrointestinal tract is a major route of absorption for many toxic agents including mercury, lead, and cadmium which appear in food and water. *Nutrients as well as toxic agents can penetrate through the epithelial cells of the villi, enter the blood and lymph vessels, and be carried to various parts of the body. *Esp. in small intestine = high absorptive capacity
Asbestos
*Has probably caused more deaths and disabling disease than any other hazardous substance *A group of six fibrous silicate minerals found almost worldwide *Utilized to reinforce clay and cloth since the Stone Age *Fireproof *85% of asbestos used today is incorporated into asbestos-cement construction materials *Some inhaled fibers lodge in air passages and cells within lungs
Lead
*Impairs brain function - hyperirritability, poor memory, or sluggishness, higher levels cause mental retardation, epileptic convulsions, coma, and death *House paint remains most notable source of lead poisoning problems *40% of lead ingested by preschoolers remains in their bodies, versus only 10% in adults *Interferes with blood cell formation *Kidney damage *Any amount of exposure carries some degree of harm, which increases as level of exposure increases
Mercury
*Inorganic metallic mercury attacks liver and kidneys; diffuses through lungs to brain; causes "Mad Hatters' Disease" - tremors and mental aberrations *Organic mercury compounds (like methyl mercury) diffuse into brain and destroy cells that control coordination; causes numbness in lips, tongue and fingertips; slurred speech, difficulty swallowing and walking; deafness and vision problems; victim loses contact with surroundings
Lead Route of Entry into Body
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Toxic Substances are those that:
1) can produce reversible or irreversible bodily injury; 2) have the capacity to cause tumors, neoplastic effects, or cancer; 3) can cause reproductive errors including mutations and teratogenic effects; 4) produce irritation or sensitization of mucous membranes 5) cause a reduction in motivation, mental alertness, or capability 6) alter behavior; or cause death of the organism
Risk Assessment Process (4 step process)
1. hazard identification 2. dose-response assessment 3. exposure assessment 4. risk characterization
Chemicals introduced
1000 to 2000 new chemicals are introduced each year into our society, there is significant opportunity for untested materials to enter our environment and expose humans, wildlife, and plants to toxic effects.
Name of Milan, Italy
1976 explosion at trichlorophenol factory released toxic cloud in suburb Severso, 37,000 people exposed; estimated millions exposed.
Asbestos Legal Status
40 countries have full or partial bans on the use of asbestos; U.S. and Canada holdout from banning the use; Canada is the largest industrial producer;' products are not legally required to be labeled as asbestos free;
Lead Sources
70% of US consumption of metal for lead storage batteries; ammunition, brass, coverings for power and communication cables, glass TV tubes, solder, and pigments; *throughout the environment, soils, water, air and food; *leaded gasoline still in 11 countries worldwide; it was phased out in US to help decline lead entering into atmosphere;
Dose-Response Relationship
A type of correlative relationship between "the characteristics of exposure to a chemical and the spectrum of effects caused by the chemical."
Asbestos Hazard
Abatement with three options: 1. Encapsulation 2. Enclosure 3. Removal. Asbestos removal has strict federal and state regulations to protect worker and general public. It must be wet down and kept damp while removing. Placed in thick plastic bags and buried in sanitary landfill separate from household wastes.
Name of North Pacific Gyre
An Island of trash twice the size of Texas floats in the middle of the Pacific Ocean, circulated by the currents of the North Pacific Gyre. The trash, which is mostly made up of plastic debris, floats as deep as 30 feet below the surface.
Name of Chernobyl, Ukraine
Chernobyl is town in northern Ukraine home to Chernobyl disaster of 1986, the worst nuclear power plant accident in history; once home to more than 14,000 residents, the town remains uninhabited and unsafe today due to extensive radioactive contamination.
Name of Citarum River, Indonesia
Citarum has been called the world's most polluted river. Around 5 million people live in the river's basin, and most of them rely on its flow for their water supply
Exposure to Chemicals
DIRECT ADVERSE EFFECTS: *Local effects - damage at the site where a chemical first comes into contact with the body. *Systemic effects - generalized distribution of the chemical throughout the body by the bloodstream to internal organs. *Target organ effects - some chemicals may confine their effects to specific organs.
Agent Orange
Dioxin formed as contaminant by-product in production of herbicides such as "agent orange," used to clear jungle vegetation during Vietnam war, Parkinson's disease, schemic heart disease, and hairy-cell leukemia
Name of Dzerzhinsk, Russia
Dzerzhinsk, Russia is the most chemically polluted city on Earth and in 2003 death rate exceeded its birth rate by 260%. More than 300,000 tons of chemical waste were improperly dumped between 1930 and 1998
Enclosure Asbestos
Feasible when the area affect is relatively small, this process involves building a nonpermeable barrier between the source of exposure and surrounding open areas.
Name of Most Polluted Spot on Earth
Lake Karachav, Russia according to world watch institute on nuclear waste. Karchav is the most polluted spot on Earth. It was used by the Soviet Union as nuclear dumping site, and now the radiation level here is so high that it is sufficient to give a lethal dose after just an hour of exposure.
Risk Analysis Limitations
Limitations of risk analysis include: *Uncertainty, variability, and effect of multiple exposures *Study biases, non-representativeness, extrapolation errors, sampling errors, random error, etc.) *Despite these limitations, risk assessment is still a valuable tool for exploring and understanding the risks of the modern world.
Name of Linfen, China
Linfen has more air pollution that any other city in the world. Sitting at the heart of China's coal belt, smog and soot from industrial pollutants and automobiles blacken the air at all hours. It is said that if you hang your laundry outside, it will turn black before it dries.
Name of Appalachia, West Virginia
Mountaintop removal mining is one of the world's most environmentally destructive practices, and it is most associated with coal mining in West Virginia's Appalachian Mountains. Whole mountaintops are removed to get to the coal, which increases erosion and runoff thick with pollutants, poisoning streams and rivers throughout the region
Bioaccumulation
PCB concentration in body increase over a period of time
Chloracne
PCB exposure had appearance of acne like skin disorder AMONG WORKERS
Name of Vapi, India
Sitting at the southern end of a 400-kilometer-long belt of industrial estates, the town of Vapi is a dumping place for chemicals of every kind. Levels of mercury in the groundwater are 96 times higher than safe levels, and heavy metals are present in the air and the local produce.
Name of Ukrainian President
Viktor Yuschenko is shown with scarred by Dixin (TCDD) poisoning during his 2004 presidential candidacy
Poison
chemical that can cause illness or death at a very low dose; approx. 3/4 t. for adult and 1/8 t. for toddler.
Name of Libby, Montana
discovery in 1919; closure in 1990s; deadly dust from Vermiculite mine; 60 times higher than any where in the U.S. asbestos causing death; W.C. Grace company that purchased mine and was sued; Superfund to clean up in 2002 - 2008 ; "Zonolite" vermiculite product
PCB laden sediment
dredging operations from upper Hudson river commenced in May 2009;. the second phase of this Superfund remediation effort was scheduled to get underway in 2011.
70,000 synthetic chemicals in the U.S. currently in commercial use
due to increase in industrial production, as well as the chemical revolution that introduced new synthetic compounds into widespread since the 20th century
Potentiation
happens when one chemical that is not toxic causes another chemical to become more toxic
Synergism
indicates that the combined effect of exposures to two or more chemicals is greater than the sum of their individual effects.
Removal Asbestos
large intensive process whereby all asbestos containing materials are physically removed from the structure.
Name of Yamuna River, India
largest tributary of the Ganges River, where it flows through Delhi its estimated that 58% of the cities waste gets dumped straight into the river; Millions of Indians still rely on these murky sewage filled waters for washing, waste disposal and drinking water.
Name of Kabwe, Zambia
lead and cadmium soak the hills of Kabwe after decades of mining and processing. Children here have lead conc 5 to 10 times the permissible US Environ. Protection Agency levels, and the ground is so contaminated that nothing can be grown.
Risk Communication
*Remember that environmental epidemiology provides information for public health decision-making and action. *The goal of risk communication is to effectively relay risk information developed through risk analysis to various interested groups. *Methods of risk communication include public hearings, emergency hotlines, information pamphlets, infomercials, and websites. *can be challenging, as it requires addressing people's different risk perceptions, biases, scientific knowledge, educational backgrounds, even race and gender. *Translating technical terminology into comprehensible terminology can increase risk communication
Exposure - Routes/Entry
*Respiratory *Skin *Gastrointestinal tract
Exposure - Respiratory
*Respiratory system by inhalation into lungs *Size of particles determines depth and how removed. Solubility of gases determines area of impact: more soluble = higher up in bronchioles; less soluble = further down in alveoli
Hazard Identification
*The initial step in risk analysis, hazard identification involves identifying agents/chemicals that present a risk to human health. *This step entails performing a qualitative assessment of a chemical's potential for negative health impacts on humans.
Exposure assessment
*The purpose of the exposure assessment is to measure or estimate a person or population's level of exposure (length, amount, route, duration, no. exposed). *Exposure is different from dose in that exposure refers to the amount of a substance in the environment, while dose is the level of a substance actually taken in by an organism. *Dose can be influenced by many factors, such as how the substance enters the body, whether absorbed through the skin, ingested with food, or inhaled *ASSUMPTIONS regarding the environmental mobility of a chemical deal with its chemical stability, whether it dissolves in water or animal fat, how quickly it evaporates or whether it binds to soil.
Latency
*The time period between initial exposure and a measurable response. *The latency period can range from a few seconds (in the case of acutely toxic agents) to several decades for agents that may be carcinogenic
Lethal Dose 50 (LD50)
*To describe toxic effects, toxicologists use the symbol LD50, which is ". . . the dosage (mg/kg body weight) causing death in 50 percent of exposed animals." *Used to compare the toxicities of different chemicals.
Incomplete Toxicological Information
*animal testing: time, expense, single chemicals *fail to detect interactive effects *fail to detect delayed effects *human studies unethical or opportunistic *lack of federal funding **private corp funding **potential bias
Dioxin (TCDD)
*believed to be most toxic substance ever created by humans *1983Times Beach, Missouri abandon their homes and evacuated the town suspension of herbicides 2,3,5-T and silvex; yet follow up failed to show death by exposure. *soil analysis had revealed high levels of dioxin due to oiling of roads for dust control in early 70s, the oil had been scavenged from a TRICHLOROPHENOL factory by a waster hauler and was heavily laced with the toxic chemical. *Formed as contaminant by-product in production of herbicides such as "agent orange," used to clear jungle vegetation during Vietnam war, Parkinson's disease, schemic heart disease, and hairy-cell leukemia *Chloracne skin disorder *Variable toxicity in different test species *Carcinogenic in most species at high levels of exposure *Endocrine disruptor *Suppression of immune system
Assumption of Toxicology
*chemicals are safe until proven otherwise? *all substances are poisons; there is none that is not a poison; the right dose differentiates a poison from a remedy or innocuous substance (i.e. NaCl, H2O)
Toxicant or "Toxic"
*describes a chemical that provokes an adverse systemic effect on living organisms; *have the ability to cause harm to organs or biochemical processes away from the site on the body where exposure occurred
Dioxin (TCDD)
*form large group of chemicals; most dangerous is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), unlike its cousin PCB has no industrial usefulness and never intentionally manufactured; *it is formed an unwanted by-product in the production of herbicides and the germ killer hexachlorophene. *can escape in atmosphere and be carried long distances; *half life in soil exceeds 10 years. *stores in fatty tissues largely thru consumption of meat, fish, and dairy products with 1% or less of the total body burden coming from contaminated water or air.
SALMON CONTAMINATED WITH PCB
*highest level from European salmon farms *lowest level from Chilie *North America levels were in between *individual should limit themselves one salmon per month to avoid increased risk of cancer
Exposure and ENTRY ROUTES
*in order for a toxic substance to produce its harmful effects on human body, a person must first be exposed to the chemical; *contact effects (strong acids, bases) *effects after entry of body
Risk Management
*is dependent on accurate risk assessment (analysis findings) - determining whether something is suspected of presenting a human health threat *is in fact dangerous, estimating how much injury or harm is likely to result from a given level of exposure and determining if those consequences are serious enough to warrant action; *It involves merging the results of risk analysis with various social factors, such as socioeconomic conditions, political pressures, and economic concerns. *three avenues of risk mangment are: education, economic, regulatory *It involves weighing the different control options for a particular risk in a population.The "best" course of action is not always the one that reduces the most risk, but rather, is the most economically feasible option, reducing the greatest amount of risk per dollar spent. *
Lead
*most common and societally devastating environmental disease in children; malleable and easy to work; *doesn't rust, corrode, or dissolve in water, and binds readily with other metals, lead has been used as an ingredient in paints, glazes, and cosmetics, and for gutters and piping. *a major metal exposure among Romans was thought to been a grape juice syrup; which was brewed in lead pots and subsequently used to sweeten foods and wine; even one teaspoon full of this syrup would have been enough to cause chronic lead poison
Polychlorinated Biphenyls (PCBs)
*most wide spread chemical contaminant known * once in the environment, they are persist for contaminates the environment decades, resisting breakdown *discharge of PCB wastes from factories into waterways - pollution (Dumping in Lake Michigan) (Hudson River) (Outboard Marine Corporation) *vaporization from paints or landfills or burning of PCB containing material can result in chemical becoming airborne and reentering into the ecosystem with precipitation; 89% of PCB entering (Lake Superior) are deposited via airborne; *leaks in industrial equipment have resulted in numerous PCB contamination such as 1979 with 200 gallons of PCB leaked from electrical transformer at a feed-processing plant in Billings, Minnesota. *accidental spills or illegal dumping are source; 1978 - 243 miles of back roads in 14 north Carolina counties. *Threat to health *conc of chemical increase as it moves from lower to higher level consumers such as carnivorous birds, fish, and humans; *experiments with Rodents, minks and monkeys caused liver disorder, miscarriage, low birth rate, abnormal multiplication of cells, and in rats (got liver cancer) *CHLORINATED HYDROCARBONS
Entry through Mouth
*oral *dermal *respiratory ------very few chemicals are equally toxic by all three routes
Risk characterization
*provides a picture of the risk that addresses its severity, likelihood, and consequences. *includes an estimate of the negative effects to exposed individuals, such as the number of cases of cancer or deaths per 100,000 people *risk is usually expressed quantitatively; *for non-carcinogens, the risk characteristic typically yields Acceptable Daily Intakes (ADIs) derived from dividing animal study NOELs by safety factors.
Dose-Response Assessment
*provides a quantitative view of the risk. *This step also involves a review of scientific studies and data. *In this case, the magnitude of response is correlated with the dose *to determine threshold levels of exposure *lowest observed effect level (LOEL) *no-observed adverse effect level (NOAEL) *no-observed effect level (NOEL)
Chronic toxicity
*refers to a chemicals ability to impair health when repeated low-dose exposure to the chemical occurs over a long time period; example: lead poison provokes anemia and nervous system damage *symptoms of chronic toxicity may take months, or years to manifest themselves; *tests carried out for avg. lifespan of test animal
Acute toxicity
*refers to its ability to cause harm as a result of one time exposure to a relatively large amount of substance; example: child drinking liquid pesticide stored in cola bottle; *LD50 (LD = lethal dose), admin in one dose, that is required to kill 50% of population of test animals within 14 day period; *the lower the LD50 the smaller the does required to kill.
Toxicity
*refers to the degree to which something is poisonous; *denotes the amount of a substance that can produce a deleterious effect
Factors that Affect the Conc and Toxicity of a Chemical
*route of entry into the body *received dose of the chemical *duration of exposure *interactions that transpire among multiple chemicals *individual sensitivity
PCB Human Exposure
*skin absorption if a person happens to touch PCB containing lubricants or oils leaking from old equipment or if he were to swim in PCB contaminated waters; *dermal exposure, less health risk than inhalation or ingestion of PCBs *inhaling PCBs evaporating from soil into the air from hazardous waste sites or landfills *drinking contaminated ground water *MOST COMMON SOURCE OF ENTRY: affecting largest number people is consumption of sports fish caught in PCB contaminated lakes and rivers; The presence of these contaminates in farmed SALMON is blamed on the fact that these fish are RAISED ON CONC FEED made of various PCB tainted fish oils and fish meals.
Absorption - RECEIVED DOSE
*the passage of substances across the membranes through some body surfaces into body fluids and tissues by any of a variety of process that may include diffusion, facilitated diffusion, active transport, or special processes.
Toxin
*usually refers to a toxic substance made by living organisms including reptiles, insects, plants, and mircoorganisms *examples of toxins: -bacterial toxins (cholera, staph. aureus) -mushroom toxins -foxglove, oleander, rhubarb, rhus radicans -nicotine -ricin (casterbean) -bee venom -snake venom
Hazardous Substance
- any chemical regulated under the following acts: *Clean Air Act (CAA) *Toxic Substance Control Act (TSCA) *Clear Water Act (CWA) (defined in the Comprehensive Environ. Response Compensation and Liability Act (CERCLA)
Name of Riachuelo Basin, Argentia
The Riachuelo Basin is a waterway whose name is synonymous with pollution. More than 3,500 factories operate along the banks of the river, a landscape that also includes 13 slums, numerous illegal sewage pipes running directly into the river, and 42 open garbage dumps.
DOSE
The term dose refers to ". . . the amount of a substance administered at one time." Several ways to describe dose: Exposure dose Absorbed dose Administered dose Total dose External dose Internal dose Biologically effective dose
Name of Libby, Montana
a town of 3,000 along the Kootenai River, has emerged as the deadliest Superfund site in U.S. history due to decades of contamination with asbestos fibers from a nearby vermiculite mine.
US Environmental Protection Agency and Occupational Safety and Health Administration
agencies in charge with writing regulations and implementing the provisions of a number of far-reaching new environmental, health, and safety laws - gave health risk assessment a major boost.
Dose-time
amount of chemical in question (dose) and the duration of exposure (time); depending on the nature of the dose-time relationship, toxicity can be categorized as either acute or chronic.
Study of poisons
any agent capable of producing a deleterious response in a biological system
Toxicologist
are scientists with training to investigate in living organisms "the adverse effects of chemicals... (including their cellular, biochemical, and molecular mechanisms of action) and assess the probability of their occurrence.
Antagonism
means that ... two chemicals administered together interfere with each other's actions or one interferes with the action of the other.
Additive
means that the combination of two chemicals produces an effect that is equal to their individual effects added together.
Hazardous
nature of substance is dependent both on its inherent capacity to do harm (e.g. its degree of toxicity, corrosiveness, flammability, etc.), and on the likelihood of that substance coming into contact with people
Methyl Parathion
one of the most toxic insecticides, present an extreme hazard to migrant farm worker entering a just sprayed field without protective clothing, the very same chemical presents virtually no hazard when stored in its original container inside a securely locked storeroom.
chloroacne
produced by Dioxin
Margin of Safety
safe level of exposure facilitates regulation - a buffer zone *based on assumptions: 1) humans are 10 times more susceptible to the toxic effects of chemicals than are lab animals 2) more vulnerable members of the pop are young children, elderly, and immunocompromised are 10 times more sensitive than the avg healthy adult;
Toxicology
study of the adverse effects of chemicals on living organisms;
Toxicants
substances that are man-made or result form human (anthropogenic) activity -pesticides -dioxin -PCBs -plasticizers (bisphenol A-bpA)
Lead Poison "Saturnine"
sweeten sour wine - lead poisoning
Encapsulation Asbestos
technique in which exposed asbestos is heavily coated with a polymer sealant to prevent further release of fibers
Testing for Toxicity
the subjects used for testing the toxicity of chemicals include the following categories: **Volunteers who have had normal or accidental exposures (natural experiments) **Animals exposed purposely (in vivo experiments) **Cells derived from human, animal, or plant sources (in vitro experiments) **Toxicants **Poisons cause illness or death at a very low dose **Acute toxicity **Chronic toxicity
