A Closer Look at Types of Biological and Chemical Hazard

1. A Closer Look at Types of Biological and Chemical Hazard

3. Bio-hazards Bacteria– single celled organisms (lack nucleus) – if they are parasites, they are classed as pathogens – can survive outside of a human body (host organism) – can form spores (dormant structures) that can survive millions of years – reproduce by asexual reproduction (mitosis)

7. Bio-hazards Viruses - much smaller than bacteria (cannot be seen with a light microscope) - are not cells therefore not considered quite “alive” - DNA inside a protein shell - can only replicate inside living cells - usually require direct contact for transmission but can survive briefly in the air (e.g. sneezing/ coughing)

11. Bio-hazards Fungi - includes moulds, yeasts, mushrooms - can reproduce by dispersing spores - most grow thread-like hyphae to draw in nutrients - can produce mycotoxins - “black mould” in houses - allergies can be severe

12. Black Mold

13. Bio-hazards Protozoans (or Protists) - single celled organisms (more complex than bacteria) - e.g. DNA is inside a nucleus - diseases include dysentery (E. coli), malaria, African sleeping sickness

15. Bio-hazards Worms - roundworms, tapeworms, flatworms - often infect people through undercooked food, infected water, skin contact with larva in soil

19. Chemical Hazards Contaminant – a chemical in an ecosystem that is normally not present Pollutant – a contaminant that causes damage within an ecosystem Toxin – a pollutant that poses a human health risk Toxicology – the study of health effects of chemicals

20. Six basic types of chemical hazard 1. Mutagens • Cause changes to genetic code in the DNA of organisms (mutations) • May (or may not) lead to disease

21. Six basic types of chemical hazard 2. Carcinogens • Cancer causing • Uncontrolled cell division (mitosis) leads to a mass of cells called a tumouror carcinoma. • Tumours block normal function of other tissues

24. 3. Teratogens • Any agent (chemical, biological or physical) that can cause a malformation of a fetus; a birth defect. • Route of entry is placental transfer (from the mother’s blood to the fetus) • Examples: alcohol, nicotine, aspirin, mercury, lead, measles, chickenpox, x-rays etc. • Example: thalidomide 1957-1961 sold as a sedative drug to pregnant women (and to aid with ‘morning sickness’). Banned in the mid 1960s (limb deformities)

25. Fetal Alcohol Syndrome

26. Thalidomide

27. 4. Allergens • Immune system over-reacts to a chemical and causes a response greater than necessary (increased production of white blood cells). • Increased asthma may be a result of more synthetic chemicals present

28. Increase in Asthma

29. 5. Neurotoxins • Attack the nervous system • Can cause slurred speech, loss of muscle control, death • E.g. heavy metals such as mercury, snake and frog venom

31. 6. Endocrine Disruptors • Interfere with the endocrine system (production of hormones or messenger molecules – such as testosterone and estrogen) • Possible link to rise in breast cancer, low birth weights, early puberty • Examples – DDT, softening chemicals in plastics, lead