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Lecture 10

EESA10 - Lecture 10.doc

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Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic

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Lecture 10: Environmental Hazards to Specific Populations Environmental Hazards to Specific Populations 1) Children’s environmental health 2) Women’s health and environment 3) Workers and noise hazards 4) Elderly and environmental health 1A. Children’s Environmental Health: Different exposure patterns b/w children and adults • Why children are so vulnerable, why are they so sensitive? • Differences in exposure patterns (i.e. Different diet of the children, different behaviour specially unique to children, how the children spend their time, and the impact of the short statue of the children) The Limited Diet of Children • Kids eat, breath, and drink more than adults but not in total in proportion to their body size • They eat, drink, and breath more air in proportion to their body size than adults – i.e. 3 to 4 times more food in proportion to their body size than adults • Also they generally eat fewer types of food – in contrast adults eat more variety of the food • Most of the kids until age 1 their diet consists of milk (breast milk, or formula, or cow’s milk) • 40% to 60% of the diet of children of one year of age is comprised of only milk alone • In mother’s milk for instance there is 3% fat; most of organic chemicals such as dioxins, DDT, or some other PCBs are fat soluble • Most of organic chemicals are fat soluble means that if the milk has that contaminant or substance in it that will definitely be in higher percentage in milk with higher fat than in milk with lower fat – that means kids will definitely be exposed to these contaminants than adults • Large quantities of specific foods – kids eat some foods much more than adults depends on taste, age, on family habit • 15 to 17 more times more apple juice for children than adults, 14 to 15 times more pears (or some other fruit) for children in relation to adults • We offer our children with more fruits at an early age than teenage years or adulthood • Kids drink significantly more water relative to their body weight – 4 times more than adults • Teenagers change our habits significantly as we drink much less water than younger kids • Instead of water teenagers drink more soft-drinks and that is the change in habit Behaviour unique to children • Kids touch their mouth very often – they explore to see if it is something hard or hot or cold • Mouthing behaviour (2-6 year olds touch their mouths about 9 times every hour) - Ingestion of soil (deliberate or compulsive behaviour) – we talked about it with heavy metals and soil, risk assessment. Kids with disabilities can do that even more; be under higher risk to ingest contaminants through the soil - Paint (in house, is also a source of lead) - Small objects (we see in the news how companies have to recall toys; they have a small object that can be ingested that represents a high risk for kids) i.e. magnets can cause infection of the gastrointestinal tract (intestines) and they can be deadly illness - Infectious agents (bacteria, viruses associated with soil, dust; because kids touch their mouths all the time they can ingest more viruses and bacteria and fungi) Kids also wash their hands less often than adults; during the day you have to reminds kids - Disinfection byproducts (drinking chlorinated water can cause more harm to kids proportion to their body size, can also ingest water from the swimming pools – their skin surface area is bigger than for adults and that is why they can be exposed to the byproducts of the swimming pools) • Participation in certain athletics (sports) and/or risky activities due to exploration behaviour - Construction sites (physical or chemical hazards; can be asbestos or other particles in air) - Swimming - Risky playing activities (in backyard or in storage rooms where chemicals are stored) - Exposure to sun (this risk is higher in teenagers) - Smoking-adolescents (some young teenagers start smoking very early and that behaviour can be very harmful and represent high risk) How do and where do children spend their time • Spend most of their time playing indoors and outdoors • For urban kids, most of their time they spend indoor (same as for adults) • Crawling and playing on the floor (dust, bacteria, viruses, radon settle down on the floor because they play there, they are close to the ground and exposed) • Outside playing on the grass (pesticides – city warns us that should not let kids or dogs play on the grass, if kids have residue from pesticides they can be exposed to it, and also kids can get skin infections) • Zoonosis – passed on from animals (i.e. pets such as cats, dogs) to humans; some of them are skin infections • In some areas dogs with some certain diseases carry some fungi for example play can possibly be transmitted over to kids The impact of short statue • The breathing zone of the adults is 4-6 feet above the floor or ground • For children is much lower (because they are close to the floor they ingest or inhale bacteria, infectious diseases, together with the dust and some other chemicals) 1B. Children’s Environmental Health: Physiological differences between children and adults • Children eat more, drink more and breathe more air than adults; this means that children burn their calories faster because they are more active, they are growing (higher metabolic rate) • Children are also significantly different in many other characteristics: dermal, gastrointestinal, and respiratory • What is the difference between skin of the adults and children? Dermal adsorption • Dermal absorption: higher ratio skin surface area to body weight than adults; it means that contact area between some medium , some chemical and the inside of the children’s body is bigger (contact is bigger) – the substance is taken in the child’s body through the skin • Skin is more permeable – more chemicals, greater amounts of substances can go through the child’s skin than the adult’s skin especially for the newborns • Newborns have a permeable skin and they have to protect newborns at the beginning of their life especially in the first 4 to 5 days • Gastrointestinal absorption: intestines are different, they have larger surface area (if surface area is bigger more chemicals can enter the body), prolong gastric emptying time – i.e. babies younger than one year need about 6 hours from mouth to feces (that means they have prolonged gastric emptying time in human body it is usually about 3-4 hours) • Calcium-lead transport mechanism – kids need lots of calcium for strong bones and all parents suggest their children to drink more milk • In children’s physiology calcium is absorbed more (from the same amount of food) • Because the mechanism of the calcium absorption and lead absorption is similar the body of the child can switch and absorb more lead instead of calcium if the certain milk or dairy product has a high concentration of lead (instead of calcium child can absorb lead just because of the similarity in the transport mechanism inside the body) • For example, children absorb about 50% of ingested lead while others absorb only 10%; that explains why very high concentration of the lead is found in the blood of some children much more than the blood in their parents even if they share the same house or apartment • Children have lower stomach acidity (especially in first year of life) that can reduce toxicity of some chemicals, not always increase - i.e. heavy metals are more toxic in acid conditions because kids have lower stomach acidity in that case that chemical will be more bio available • Some other chemicals will be less toxic (it means that this depends on the type of chemical) • Respiratory absorption: through the lungs; also there is some difference as kids breath more air proportion to their body but also they don’t have very well developed blood brain barrier • Blood brain barrier is very well developed in adults only; it is a mechanism that will prevent substances to enter and cause the harm in brain: physiological mechanism that will prevent entering substances from the blood and harm the brain • Kids don’t have that mechanism developed well yet because their nervous system or brain is more vulnerable, more sensitive to some substances • At the same time, kids have greater blood flow to the brain and other organs – more blood is coming to the brain than for the adults • The size of some organs relative to body mass/size is greater • Infant brain represents 13% of the total body mass while adults brain only constitutes 2% of the total body mass (almost 7 times more bigger brain in comparison to the body size or mass of kids in comparison to adults) • Biotransformation processes are less developed in kids – some mechanisms that will result in breakdown of the certain chemicals inside body are not very well developed • Kids are growing/developing rapidly, their cells are multiplying faster; and a whole life to live which means more time to develop disease • As a result, diseases such as diarrheal more common in kids, also asthma, increasing number of cancer cases in children Women’s Health and the Environment • What we want to discuss now is differences and specifics for women – how the environmental factors affect women’s health • Most diseases that are seen in men are also seen in women, there is not much difference • But some diseases are specifically associated with women’s gender something that is physiologically working like that • These diseases are mostly associated with pregnancy, with abortion, all coming because of the women’s role in reproduction and of course in raising and nursing of children later • Why is it so important for us and why do we see so much research done in this area? It is because women affect the health of their children – healthy mother means healthy child (talking about pregnant woman), usually means healthy child • All diseases that are not discovered in certain women that were not aware of it will show up during the pregnancy – that is specific for the woman; most of the diseases associated have the environmental cause, many of them • Differences coming also as a result of higher fat content in women’s body; just means that physiologically women have a higher fat content • In puberty girls will get more fat than
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