Human Health & Toxicology

Three Major Categories Physical – Natural disasters Biological – disease Chemical – Natural or synthetic * Most deaths

Infectious Disease Caused by pathogens – Bacteria, virus, fungi, protist, & helminths Top three infectious diseases – Respiratory – AIDS – Diarrhea (parasitic worms)

Infectious Disease Categories Chronic – Disease that slowly impairs function – Ex. Heart disease, most cancers Acute – Rapidly impairs bodily functions – Ex. Ebola

Risk Factors (Chronic) Low income countries – Poverty – Unsafe drinking water – Poor sanitation – Malnutrition High income countries – Availability of tobacco – Less active lifestyle – Poor nutrition/overeating

Historically Important Infectious Diseases Plague Cause: Yersinia pestis (bacteria) Vector: fleas 1300 – ¼ of European population died Today - antibiotics

Historically Important Infectious Diseases Malaria Cause: Plasmodium (protist) Vector: mosquito Hardest hit: Africa, Asia, Middle East, & Central & South America 1951 – eradicated from the US

Historically Important Infectious Diseases Tuberculosis Cause: Mycobacterium tuberculosis (bacteria) Affects the lungs Today – antibiotics Drug resistant strains – Hardest hit: Africa & Russia (20% MRTb)Russia

Emergent Infectious Diseases HIV/AIDS Cause: Human immunodeficiency virus Discovered in the 1980s (coined in 1982) Jump from chimpanzees to humans Today – 33 million worldwide (1 million US) With meds – 24 yrs Without meds – 10 yrs Poverty can affect access to meds

HIV/AIDS Timeline of Events 1959 – first case confirmed from male in Congo from preserved blood samples 1980 – first death in US 1996 – first meds published to block progression of AIDS 1999 – study published to suggestion the retrovirus began in chimpanzees 2007 – first patient cured via bone marrow transplant (Germany) – Still HIV free in – first toddler cured by bone marrow transplant but relapsed

Emergent Infectious Diseases Mad Cow Disease Cause: Prions (proteins that act as pathogens) Vector: transmission requires an uninfected cow to consume the nervous system of an affect cow 1980 in Europe – many cow diets included ground up remains of cattle for extra protein

Emergent Infectious Diseases Ebola Cause: Ebola virus 1 st seen: Republic of Congo (Ebola River) Also infected other primates 50-89% death rate Source: Remains unknown

Harmful Chemical Categories Neurotoxins Carcinogens Teratogens Allergens Endocrine disruptors

Neurotoxins Disrupts the nervous system of animals Insecticides Lead – Improved – eliminate lead in gas and paint Mercury

Carcinogens Chemicals that cause cancer – Interfering with metabolic processes – Damaging DNA Examples: – Asbestos – Formaldehyde – Tobacco

Teratogen Chemicals that interfere with the normal development of embryos or fetuses Famous teratogen: ThalidomideThalidomide – Morning sickness – Birth defects Famous teratogen: Alcohol – Fetal alcohol syndrome – Reduce birth weight Damage to brain & nervous system

Allergens Chemicals that cause an abnormally high immune response from the immune system

Endocrine Disruptors Chemicals that interfere with normal hormone function in animals Hormone binding = response Sources: agriculture, birth control (unfiltered in sewage, pesticides

Biomagnification The process by which toxic substances accumulate at increasingly high concentrations in progressively higher trophic levels

Two Characteristics Non Biodegradable Non Biodegradable Fat soluble Fat soluble – Accumulate in fat of body Bioaccumulation Bioaccumulation – Stored energy is passed to higher trophic levels

DDT - Pesticide Dichloro – Diphenyl – Trichloroethane Dichloro – Diphenyl – Trichloroethane Use in WWII to control malaria Use in WWII to control malaria After war – agricultural insecticide After war – agricultural insecticide 1972 – Banned in US 1972 – Banned in US

Bald Eagle DDT affected offspring DDT affected offspring Affects not seen initially Affects not seen initially

Egg Shell Thinning Caused by DDE (broken down DDT)Caused by DDE (broken down DDT) Blocks calcium carbonate productionBlocks calcium carbonate production

Shell Thinning

Toxicology The study of harmful effects of chemicals on humans & other organisms Toxicity – measure of the harmfulness of a substance (the ability to cause injury, illness, or death) Basic principle: Any synthetic of natural chemical can be harmful if ingested in a large enough quantity

Exposure Key factors: – Dose - the amount of a harmful chemical that a person has ingested, inhaled, or absorbed – Response – resulting damage to health Variables: – Age – Genetics – Functionality of detox systems (liver, kidney, etc.) – Solubility – Persistence

Response Health damage Acute – immediate or rapid – Dizziness, nausea, or death Chronic – Liver damage

Dose Response Curve Median Lethal Dose – LD50 – The dose that can kill 50% of the population within a 18 day period