ToxicologyToxicology

The study of poisons and their effects, on living systems

Love Canal Cleanup Finished, Mutants Return to Homes

We knew there were too many miscarriages, too many birth defects, too many central nervous system problems, too many urinary tract disorders, and too much asthma and other respiratory problems among us."

Health: A state of complete physical, mental, and social well-being

Disease: A deleterious change in the body’s condition in response to an environmental factor that could be nutritional, chemical, biological, or psychological

Morbidity: Illness

Types of Environmental Health Hazards

Infectious Diseases Toxic Chemicals Natural or Synthetic Toxins Physical Agents, Trauma and Stress Diet

Pathogens are infectious organisms

Bacterial Protozoans (guardia) Fungal Invertebrate Animals Viruses are non living

Bacterial Infections:

Trachoma is an inflammation of eye

Sexual Transmitted Diseases (gonorrhea and syphilis)

Respiratory Diseases: Pneumonia, tuberculosis, influenza, and pertussis

Bacteria have developed resistance to antibiotics

Improved drugs and sanitation can eliminate some diseases

Trachoma,the most commonly contracted STD, caused by Chlamydia trachomatis

Emergent diseases

Those not previously known or that have been absent for more than 20 year

*many are viruses

Viral Infection

SARS and Bird flu HANTA, Ebola West Nile virus causes encephalitis HIV and AIDS

Fungal

Sudden oak death Fungal spores *black mold

Protozoans

Malaria: Infection of red blood cells by the protozoan Plasmodium spread by the Anopheles mosquito

Giardia: dysentery Amoeba:dysentery

Invertebrate Animals (Parasitic)

Flatworms (flukes) and tapeworms Nematodes (roundworms)

– such as hookworms, guinea worms– Filariasis worms block lymphatic vessels – causes elephantiasis

Elephantiasis Filariasis

Guinea worms

Caused by Nematodes (Roundworms)

prions

Proteins resistant to temperature. They cause Chronic Wasting in Wild Animals and Mad Cow Disease also known as Creutzfelt-Jacop disease

Toxic Chemicals

Hazardous: Dangerous Toxic: Poisonous Irritants: Corrosives (acid), caustics

(base), and other substances that damage biological tissues

Respiratory Fibrotic Agents: Irritants that damage the lungs

Asphyxiants: Chemicals that exclude oxygen or actively interfere with oxygen uptake and distribution (i.e. MIC)

Allergens: Substances that activate the immune system. Some act as Antigens which are recognized as foreign by white blood cells. Antigens cause the immune system to produce Antibodies.

Cancer: Invasive, out-of-control cell growth that results in malignant tumors

Carcinogens: Substances that cause cancer Promoter: Bases sequences in DNA that regulate

expression of that gene Terratogens: discussed further

Mutagen: with change the base sequence in DNA, may be harmless or harmful.

Mutagens: Agents that damage or alter DNA

Teratogens: Factors that cause abnormalities during embryonic growth and development (example: thalidomide)– Fetal Alcohol Syndrome: Symptoms including

craniofacial abnormalities, developmental delays, behavioral problems, and mental defects.

– Thalidamine: used to prevent morning sickness and in treatment of leprosy.

Thalidomide for morning sickness

Carcinogens

acrylamide

aflatoxin

Francis Oldem Kelsey

Prevent FDA from approving

Prevented 1000 birth defects in USA

Awarded President’s Award for Distinguished

Federal Civilian Service

Endocrine Disrupters Neurotoxins: Attack nerve cells

– Heavy metals (mercury, lead)– Chloronated hydrocarbons (DDT, dioxin)

disrupt nerve cell membranes– Organophosphates (pesticides

organophosphates

mercury

How Do Environmental Toxins Enter Our Bodies?

introduced into our lives everyday depend on where we live They are in the air you breath, the food you

eat, water, buildings, pesticides, and consumer products.

They are the byproducts of industry

Def: science that studies poisons or toxics Pathways from environment -> us

– oral ingestion– inhalation– percutaneous absorption (skin)

Def: science that studies poisons or toxics Pathways from environment -> us

– oral ingestion– inhalation– percutaneous absorption (skin)

Basic ConceptsBasic Concepts

17.8% of California’s lakes are under fish consumption advisories due to mercury, dioxins and other Persistent Bioaccumulative Toxins!!!

The average household uses and stores more than 60 hazardous materials, including household cleaners, automotive products, paints, solvents and pesticides

Household sources of Toxic Chemicals

Off the shelf pesticides, herbicides, fungicides and insecticides

Paints and paint cleaning supplies Household cleaning solutions, laundry

detergents with phosphates Bleached paper products

Over 150 chemicals found in the average home have been linked to allergies, birth defects, cancer and psychological abnormalities

Consumer Product Safety Commissionwww.earthwellness.com

Some of the biggies

Dioxin is an unintentional bi-product of industrial processes using chlorine. It includes more than 200 chemicals.

PVC, Polyvinyl Chloride, is the most widely used plastic

Physical Agents, Trauma, and Stress

Trauma: Injury caused by accidents or violence

Stress: Physical, chemical, or emotional factors that place a strain on an organism for which there is inadequate adaptation

Movement, Distribution and Fate of the Toxin

Solubility

water vs fat soluble Bioaccumulation and Biomagnification Persistence Chemical Interaction

Bioaccumulation and Biomagnification

Bioaccumulation: The ability of cells to absorb and store of a select molecules

When is this beneficial vs detrimental? Biomagnification: the toxin level

accumulates in those organisms higher up in the food chain. i.e. DDT

Chemical Interactions

Antagonistic: One chemical counteracts the effects of another– Vitamins A, C, and E reduce response of some

carcinogens Additive and Synergistic: : two chemical

that occur together exacerbates the effects of another

How Do We Measure Toxicity

Animal testing Toxicity ratings Acute verses chronic doses and effects Detection limits

Animal Testing

LD50: The dose of a toxic chemical to which 50% of the test population is sensitive 9.11, 9.12

Acute vs Chronic Doses and Effects

Acute Effects: Effects causes by a single exposure to the toxin resulting in an immediate health crisis

Chronic Effects: Long lasting or permanent effects

Exposures: If long lasting can be chronic 9.13

Fig 8.17

Risk

Risk: The probability of harm times the probability of exposure

Assessment & Management

High Risk: Habitat destruction, loss of biodiversity

Medium Risk: Toxins

Low Risk Oil Spills, Radionuclides

What happened in Bhopal, India?

Methylisocyanate

An irritant, causes burning and swelling of soft tissue

The lack of oxygen lead to death Blindness to the survivors

What happened in Chernobyle

How Can We Reduce Our Risk of Exposure to Environmental Toxins?

Increase your awarenesspass that knowledge on to friends and family

Limit your exposure to toxic chemicals by knowing what is in the products you buy for yourself and family.

Use minimal amounts of organic pesticides and fertilizers and encourage your neighbors to do the same Express your views to and make demands on

your local representatives, school board, federal agencies

Change your lifestyle by minimizing your use and exposure to toxic substances! Encourage those around you to change theirs

Buy organic fruits and vegetables, meats, and dairy products as much as possible.

Limit your use of products (toilet paper, tampons, and other paper products) which have been through a chlorine process to whiten the product.

Limit your exposure to plastic products. Use minimal amounts of organic pesticides and

fertilizers and encourage your neighbors to do the same.