Environment and Nutrition Flashcards
Diseases predicted to increase due to Climate Change
- Cardiovascular disease.
- Cerebrovascular disease.
- Respiratory disease.
- Gastroenteritis.
- Vector-borne infectious diseases.
- Malnutrition.
How is climate change predicted to increase the incidence of cardiovascular, cerebrovascular and respiratory disease
Increased heat waves and air pollution –> increased exacerbations.
How is climate change predicted to increase the incidence of gastroenteritis / cholera / other foodborne and waterborne infections
Increase of flooding, heavy rain and other environmental disasters –> increased contamination of food / water and disruption of clean water supplies / sewage treatments.
How is climate change predicted to increase the incidence of Vector-borne infections
Increased temperatures, crop failures and extreme weather variation –> changes to vector numbers and geographic distributions.
How is climate change predicted to increase the incidence of malnutrition
Changes in local climate –> disruption of crop production.^
^Likely to be most severe in tropical climates.
Toxicity
Poison
Any substance given at a dosage which causes harmful effects.
Xenobiotics
Exogenous chemical in the environment that are absorbed into the body and stored in various organs or metabolised.
Metabolised either to:
- Inactive water soluble compounds (which are excreted).^
OR
- Toxic metabolites.
^Detoxification.
Xenobiotic Metabolism
- Phase 1 reaction = Hydrolysis, reduction or oxidation of Xenobiotic with help of Cytochrome P-450 enzyme catalyst.
- Primary metabolite.
- Phase 2 reaction = Glucuronidation, sulfation, mehtylation or conjugation with glutathione (GSH).
- Water soluble compounds OR toxic metabolites.
- Excretion OR cell damage.
Cytochrome P450 enzymes (CYPs)
- Heme-containing enzymes.
- Each has its own preferred substrate.
- Primarily in endoplasmic reticulum of hepatocytes.
- Catalyses xenobiotic reactions to either inactive water-soluble OR active toxic metabolites.
- By-product of either reaction = ROS (reactive oxygen species).
Cytochrome P-450 enzyme (CYP) inducers
- Environmental chemicals.
- Drugs.
- Smoking.
- EtOH.
- Hormones.
NB. Fasting or starvation decrease CYP activity
Effects of cytochrome P-450 enzyme (CYP) inducers
- Inducer binds specific nuclear receptors.
- Combine with retinoic X receptor (RXR).
- Complex formed binds 5’-flanking region promotor elements of CYP gene.
- Activates transcription of CYP.
- Increased CYP activity.
Receptors which bind inducers to activate cytochrome P-450 (CYP)
- Aryl hydrocarbon receptor.
- Peroxisome proliferator-activated receptors (PPARs).
- Constitute androstane receptor (CAR).
- Pregnane X receptor (PXR).
Most common Outdoor Air Pollutants
- Ground-level ozone (gas formed by nitrogen oxide and volatile organic compound reactions in presence of sunlight)
- Sulfur dioxide.
- Acid aerosols.
- Particles < 10 microm diameter (“soot”).
Health effects of Outdoor Air Pollutants:
-Ground-level Ozone
Healthy adults and children:
- Decreased lung function.
- Increased airway reactivity.
- Lung inflammation.
Athletes / outdoor workers / asthmatics:
- Decreased exercise capacity.
- Increased hospitalisatons.
Health effects of Outdoor Air Pollutants:
-Nitrogen dioxide
Healthy adults:
- Increased airway reactivity.
Asthmatics:
- Decreased lung function.
Children:
- Increased respiratory infections.
Health effects of Outdoor Air Pollutants:
-Sulfur dioxide
Healthy adults:
- Increased respiratory symptoms.
Chronic lung disease patients:
- Increased mortality.
Asthmatics:
- Increased hospitalisation.
- Decreased lung function.
Health effects of Outdoor Air Pollutants:
-Acid aerosols
Healthy adults:
- Altered mucociliary clearance.
Children:
- Increased respiratory infections.
Asthmatics:
- Decreased lung function.
- Increased hospitalisations.
Health effects of Outdoor Air Pollutants:
-Particulate matter (“soot”)
Children:
- Increased respiratory infections.
Chronic lung or heart disease patients:
- Decreased lung function.
Asthmatics:
- Excess mortality.
- Increased attacks.
Carbon monoxide
- Non-irritating.
- Colourless.
- Odourless.
- Tasteless.
- Produced during incomplete oxidation of hydrocarbons (e.g. car engines, furnaces, cigarettes).
- Bind Hb with high affinity (carboxyHb) –> CNS depression and systemic asphyxiation..
Chronic CO poisoning
- Occurs when exposed to low-level persistent CO.
- CarboxyHb is very stable once formed.
- Persistnet carboxyHb –> slowly developing hypoxia –> widespread iscaemic changes in CNS.^
- May have permanent memory / vision / hearing / speech loss despite cessation of CO exposure.
- Dx by blood carboxyHb levels.
^Most commonly basal ganglia and lenticular nuclei.
Acute CO poisoning
- Usually accidental or suicide attempt.
- Chrctrsd by generalized cherry-red coloured skin and mucous membranes (in light-skinned people).
- Rapid death = no morphologic changes.
- Slower death = edematous brain, punctate haemorrhages, hypoxia-induced neuronal changes.
Common Indoor Air Pollutants
- Smoke.
- Bioaerosols.
- Radon.
- Formaldehyde.
- CO.
- NO2.
- Asbestos.
Health effects of Indoor Air Pollutants:
-Smoke
From burning of organic materials (wood, dung, charcoal).
- Lung infections.
- Cancer.^
^May contain carcinogenic polycyclic hydrocarbons.
Indoor Air Pollutants:
Bioaerosols:
-Examples
- Microbes (e.g. Legionnaires, viruses).
- Allergens (e.g. pet dander, dust mites, fungi, moulds).
Indoor Air Pollutants:
-Radon
- Radioactive gas.
- Derived from uranium.
- Present in soil and homes.
Health effects of Indoor Air Pollutants:
-Radon
- Lung cancer.
Health effects of Indoor Air Pollutants:
-Formaldehyde
Carcinogen
- Breathing difficulties.
- Burning sensation in eyes and throat.
- Trigger asthma attacks.
NB. In concentrations of >=0.1 ppm.
Sources of Lead:
-Occupational
- Spray painting.
- Foundry work.
- Mining and extracting lead.
- Battery manufacturing.
Sources of Lead:
-Non-occupational
- Water supply.^
- Paint dust and flakes^ in older housing.
- Automotive exhaust.
- Urban soil.
^Most common sources.
Lead Absorption in Children
from food
50% or greater.