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