Chapter 17 Toxicology
Malaria
1/5 people are at risk from Malaria Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought. 90% of deaths are children under 5 Treatment costs ~ $1 - 2 /person Spraying insides of homes with pesticide DDT greatly reduces the number of malaria cases; under international treaty enacted in 2002, DDT is being phased out in developing countries
Biological hazards
14,000 pathogens Pathogen = disease carrying organism
Overuse of antibiotics
2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily
Federal and state governments do not regulate about
99.5% of the commercially used chemicals in the U.S.
Asbestos
A mineral with long thin fibers •As a result it has •Good insulation to heat •Muffles sound •Resists fire •When disturbed it can release fibers that may get inhaled and embedded into the lungs •Result: may cause lung cancer (mesothelioma), and asbestosis, •Removing Asbestos may be more hazardous than leaving it in place as improper removal increases airborne exposure.
Mutagen
Alter the DNA in cells
Top 5 toxins
Arsenic (treated lumber, past use in pesticides and naturally occurring) Lead ( paint, glazes and gasoline) Mercury ( mostly from coal burning) Vinyl chlorides ( mostly from plastics) Polychlorinated biphenols ( PCB) (mostly from electric insulation)
Neurotoxins
Attack nerve cells Heavy metals - (water soluble= easily absorbed) lead, mercury, cadmium, - kills nerve cells Others block receptors so neurotransmitters cannot bind to them
Bacteria
Cells Prokaryotes and Eukaryotes Examples: Lyme disease (tick=vector) Cholera (dirty water) Tuberculosis - close to 1/3 of world population infected; ~10% will develop bad case pneumonia
Children more susceptible because...
Children breathe more air, drink more water, and eat more food per unit of body weight than adults, are exposed to toxins when they put their fingers or other objects in their mouths, have less well-developed immune systems and detoxification processes
Ebola solutions
Contain the virus It is not a death sentence if identified early and given proper medical care Provide timely and proper health care Provide proper burial Provide education to prevent future outbreaks - actual host unknown - fruit bat or monkey/ape
Fungi
Decomposing organisms Yeast, molds, mushrooms Examples Athlete's foot, Ring worm
Most individuals evaluate the relative risk they face based on:
Degree of control. Fear of unknown. Whether we voluntarily take the risk. Whether risk is catastrophic. Unfair distribution of risk. Sometimes misleading information, denial, and irrational fears can cloud judgment
Emerging diseases
Diseases appearing in the human population for the first time or suddenly beginning to spread rapidly Humans have little or no resistance, and no vaccines have been developed
Endocrine disruptors
Endocrine system regulates hormones effect growth and reproduction Called Hormone active agents ( HAA) or hormone mimics EX = DDT, PCB, Dioxins, Lead, BPA Can mimic estrogen ( DDT)
Antigens
Fights the disease by stimulating antibodies Antibiotics, vaccines, anti-fungals
Toxicity depends on..
Genetic predisposition Persistence Chemical synergy = two toxins together have a greater effect than the sum of the 2 Solubility can lead to... Bioaccumulation and biomagnification
Fighting malaria
Giving children insecticide-treated nets over their beds reduces mortality from all causes Bed nets, indoor DDT spraying, and effective drugs reduce malaria deaths
Virus examples
Influenza, pneumonia = world's number ONE viral killer Transmitted by fluids and airborne particles Kills about 1 million people/year ( mostly young/old/weak), mutates rapidly, jumps from animals to humans Hepatitis B = transmitted like HIV ( 3rd viral killer) Est. 2 billion people, disease of the liver West Nile= from 1999-2006 1,000 in US died Carried by mosquito; causes encephalitis West Nile, HIV, ebola
Chemical hazards are...
Is toxic Is flammable Is explosive An irritant Interferes with oxygen uptake Induce allergic reactions
World Health Organization (WHO)
Monitors health events worldwide and coordinates international responses to emerging diseases
Carcinogens
Most are mutagens Cancer cells experience unregulated growth (mitosis) or cells don't die at end of lifetime
Virus
No cell, very simple RNA/DNA in a protein shell They do not metabolize their own nutrients; they use their hosts by taking over their cells
Protists
Paramecium, kelp, mold Ex. Malaria: mosquito (mosquito is the vector), invade liver then red blood cells, 1 in 5 people are at risk, kills 2-3 million people per year Giardiasis Dysentery
Allergen
Recognized by human immune system as foreign and immune system responds Secretes histamines - causes a set of symptoms to try to remove objects Symptoms = sneezing, coughing, runny nose, watery eyes
Centers for Disease Control and Prevention (CDC)
Responds to emerging diseases in the United States; the CDC developed pandemic plans to deal with the spread of the H1N1 flu virus
Solutions to spread of illness
Safe drinking water hygiene, and handwashing in clean water Reduce use of unnecessary antibiotics Reduce hunger and malnutrition Immunization Education/ condoms for HIV Hydration for dysentery
Risk analysis equation
System reliability (%) = Technology reliability x human reliability
Tuberculosis
The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020. Spread by inhaling infected particles Recent increases in TB are due to: Lack of TB screening and control programs especially in developing countries due to expenses. Genetic resistance to the most effective antibiotics.
Pandemic
a global epidemic i.e AIDS
Epidemic
a large scale outbreak in an area/country
Vulnerability
a measure of a the likelihood of exposure to a hazard
Pollution
according to the EPA, "the presence of a substance in the environment that, because of its chemical composition or quantity, prevents the functioning of natural processes and leads to undesirable environmental & health effects."
Dose
amount and duration of exposure Inhaled, ingested, absorbed
Hazard
anything that can cause (1) injury, disease, or death to humans; (2) damage to property; or (3) degradation of the environment
Chemical hazards are regulated by...
by CERCLA - comprehensive environmental response, compensation and liability act Superfund created the Agency for Toxic Substances and Disease Registry- 275 toxins EPA in charge of cleanup of abandoned/uncontrolled waste sites with trust fund
Teratogens
cause birth defects Thalidomide - 1960's - sleeping aid Prevented limb development in fetuses Alcohol - fetal alcohol syndrome Delayed development of fetuses
Chemical hazards
chemicals in environment
Physical hazards
fire, earthquakes etc
LD50
is the dose at which 50% of your subjects experienced the death
Rotavirus
little-known virus tat causes any childhood death, responsible for most cases of severe diarrhea
Vector control
methods of controlling a parasite or disease by attacking the vector
Risk perceptions
non experts' intuitive judgements about risks, which often are not in agreement with the level of risk as judged by experts
Nonbiodegradable
not able to be consumed or broken down by biological organisms; ex. plastics, aluminums, etc.
Dose-response assessment
part of risk assessment, establishing the number of cancers that might develop due to exposure to different doses of a chemical
Exposure assessment
part of risk assessment, identifying human groups exposed to a chemical and calculating the doses and length of time of their exposure
Precautionary principles
principle that says that where there are threats of serious or irreversible damage, the absence of scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation
Risk
probability of suffering injury, disease, death, or some other loss as a result of exposure to a hazard
Animal testing
procedure used to assess the toxicity of chemical substances using rats, mice, and guinea pigs as surrogates for humans who might be exposed to the substances
Risk characterization
process of determining the level of risk and its accompanying uncertainties after hazard assessments, dose-response assessment, and exposure assessment have been accomplished
Cultural hazards
smoking, unsafe working conditions, drugs, poor diet, homicides, driving, drinking, poverty
Genetic resistance
spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria
Epidemiology
study of the causes of disease through an examination and comparison of large populations of people living n different areas, lifestyles, etc.
Toxicology
study of the impacts of toxic substances on human health and the pathways by which such substances reach humans
Pollutant
substance that contaminates air, water, or soil
Environment
the combo of all things and factors external to the individual or population of organisms in question
Risk management
the evaluation of the possibility of an outcome and how to minimize it
Mortality
the incidence of death in a population
Morbidity
the incidence of disease in a population (number of cases)
Risk assessment
the possibility of an outcome
Underweight
the world's number one health risk factor; the effects of undernourishment on children that prevent their normal growth
AIDS/HIV
worlds 2nd largest viral killer About 1.1 million in US There is no vaccine There is no cure Every year about 3 million die Pandemic = worldwide epidemic
Volatile Organic Compounds VOC's in your home
•Carbon containing compounds that are readily released into the atmosphere •Human airborne exposure is usually low level and so varied in a home environment, risk is hard to assess. •A VOC's known to be problematic
Carbon monoxide
•Colorless, odorless gas •Sources are leaky or unvented stoves/furnaces, car exhaust and tobacco smoke •Low levels gives headaches, fatigue and/or nausea •High levels can result is death •Prevention is with a carbon monoxide detector on every floor
Radon
•Colorless, odorless, heavy, radioactive gas •Naturally occurring & is released with radioactive decay of of uranium found in rocks and soils •It can seep up from the ground into the house •The geology of the region will determine potential risk. •reducing one's risk from soils suction systems, ventilation systems and not using a basement as a living space
Lead
•Used in paint prior to 1978 and in water pipes until 1986. (Also in some pottery and toys) •When ingested can damage the brain, liver, kidneys, and stomach •In children 6 and under can lead to learning problems, behavioral abnormalities, hearing loss, anemia or death •In CT children are tested for lead in yearly check ups