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Lecture 10

Lecture 10 Study Guide

Environmental Science
Course Code
Jovan Stefanovic

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Lecture #10: Environmental Hazards to Specific Populations
Wednesday, March 30th/2011
Children more vulnerable than adults
Elderly also quite vulnerable
Childrens Environmental Health
The limited diet of children
oChildrens diet is different from adults
oEat 3-4 times more food in proportion to their body size than adults; more
water, breathe more air
o fewer types of foods
oLarge quantities of specific foods
E.g. Breastmilk/formula/cows milk contains fat and if it contains
contaminants, dioxins etc. then they are exposed to these more than
adults because they rely on it for their diet
E.g. Fruits babies consume more fruits on average than adults; if
fruits contain pesticides, then they are more exposed to this
oDrink more water relative to their body height
More water = more nitrates more nitrite accumulation in the body
** Young adults e.g. 18 yrs. Have reduced dairy and water intake they switch to salty
drinks and fast foods/fatty foods because they’re independent, they are also exposed to
unwanted chemicals through their diet
Behaviours unique to children
oMouthing behaviour
2-6 year olds touch their mouths about 9 times every hour &
dont wash their hands very often
If anything is contaminated, theyre exposed to unwanted

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Ingestion of soil/dust thru deliberate or compulsive behaviour
Paint playing in painted backyard/deck
Small objects e.g. toys recalled several years ago b/c of
contaminated magnets; 1 child even died
Infectious agents anything that can cause infection
Disinfection byproducts e.g. swimming pools; organic matter
reacts with chlorine; children like swimming; swim rigorously &
swallow much of the water
oParticipation in certain athletics and/or risky activities
Construction sites
Risky playing activities
Exposure to sun adolescents more prone b/c consider themselves
independent and dont use much sunscreen; are careless
Smoking adolescents
How and where children spend their time
oSpend most of their time indoors
oCrawl/play on the floor
Infectious agents
Radon –heavy, stays closer to the floor, enters 1st floor and
oPlaying on the grass
Pesticides not used in Toronto
Skin infections animal to human transfer e.g. fungi on skin

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The impact of short statue
oThe breathing zone of the adults is 4-6 feet above the floor or ground
oFor children, breathing zone is much lower therefore, they can inhale
more dust and anything else thats close to the ground
Physiological Differences between children and adults
oChildren have a higher metabolic rate b/c they are more active than
adults; as a result, they eat more, drink more, breathe more
oDermal adsorption
Higher ratio of skin surface area to body weight than adults
More skin = higher contact area for contaminants
Skin is more permeable more chemicals can enter penetrate and
enter body
oGastrointestinal adsorption
Large surface area of intestine bigger contact area for food
Prolong gastric emptying times e.g. @ 8 months GET = 8 h >
adult GET
Calcium-Lead transport mechanism calcium similar to lead??
Lower stomach acidity can be positive or negative; some
chemicals readily absorbed and others not as easily; e.g. heavy metals,
more/better consumed in acidic conditions
oRespiratory adsorption
Breathe twice as much air
Blood-brain barrier depends on and develops with age; in kids, brain is
bigger??, more water in brain
oGreater blood flow to brain and other organs if blood contains toxicants,
more easily spread
oThe size of some organs relative to body mass is greater
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