a closer look at types of biological and chemical hazard
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A Closer Look at Types of Biological and Chemical Hazard. 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) - PowerPoint PPT PresentationTRANSCRIPT
A Closer Look at Types of Biological and Chemical Hazard
Bio-hazardsBacteria
– 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)
Bio-hazardsViruses - 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)
Bio-hazardsFungi - 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
Black Mold
Bio-hazardsProtozoans (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
Bio-hazardsWorms - roundworms, tapeworms,
flatworms - often infect people through
undercooked food, infected water, skin contact with larva in soil
Chemical HazardsContaminant – a chemical in an ecosystem that is normally not
presentPollutant – a contaminant that
causes damage within an ecosystem Toxin – a pollutant that poses a
human health riskToxicology – the study of health
effects of chemicals
Six basic types of chemical hazard1. Mutagens- Cause changes to genetic code in
the DNA of organisms (mutations)- May (or may not) lead to disease
Six basic types of chemical hazard
2. Carcinogens
- Cancer causing- Uncontrolled cell division
(mitosis) leads to a mass of cells called a tumour or carcinoma.
- Tumours block normal function of other tissues
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)
Fetal Alcohol Syndrome
Thalidomide
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
Increase in Asthma
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
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
