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Lecture 10

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Environmental Science

Gagandeep Saluja 03/26/2008 Human Health and the Environment Lecture 10: Environmental Hazards to Specific Populations (Children, Women, Occupational Hazards), War and the Environment, and Population Growth We will cover 3 topics today: 1) Environmental Hazards to Specific Populations 2) War and the Environment 3) Population Growth • Population growth and different environmental and human health adverse affects • What are specific populations that are more vulnerable to some environmental hazards? • We are going to talk about children’s environmental health, women’s health in relation with the environment, and workers (occupational hazards) • During this course from lecture 1 we mentioned many of these potential hazards (i.e. chemical and physical) to workers • We talk about DDT, dioxins, or some other chemicals • Today we will talk about noise; we will focus on noise • Noise is a big hazard to workers health • Elderly (our seniors) are at a high environmental risk 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 between children and adults • Why children are so vulnerable, why are they so sensitive? • Basically 2 major reasons we recognize: o Some differences between the adults and children (differences in exposure patterns in everyday child’s life; they do not have everyday behaviour like adults) o What is meant by the exposure pattern? 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 Life Support EESA10H3 S Gagandeep Saluja 03/26/2008 • Also they generally eat fewer types of food – in contrast adults of course eat more variety of the food • For example, 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 • 3% is fat in milk • Kids ages 1 to 3 need cow’s homo milk which has 3.25% fat • 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 but some foods much more than others • For example, about 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 say later on in the teenage years or adulthood • Kids drink significantly more water relative to their body weight – 4 times more than adults kids younger than 6 months of age • Later on in life as teenagers we 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 • If the apple juice or foods are contaminated with some chemicals it means higher exposition of the cancer through these chemicals • That behaviour pattern results in higher exposition 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, can be because they are curious to know i.e. 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, and kids because of their curiosity can ingest paint) - 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 Life Support EESA10H3 S Gagandeep Saluja 03/26/2008 bacteria and fungi) Kids also wash their hands less often than adults; during the day you have to reminds kids to wash their hands - 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 because of exploration behaviour - Construction sites (physical or chemical hazards; can be asbestos or some other particles in the air) - Swimming - Risky playing activities (in backyard or in our storage rooms, store chemicals, pesticides – is a big risk for kids) - Exposure to sun (this risk is higher in teenagers than adolescence because mom applies sunscreen on young children) - 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 as we stay mostly indoor) • 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’s Environmental Health: the difference between adults and children in some physiological processes/differences exist • 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) Life Support EESA10H3 S Gagandeep Saluja 03/26/2008 • Children are also significantly different in many other characteristics: dermal, gastrointestinal, and respiratory and probably many others (listed only a couple which we should know) • 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: simply 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% (it is 5 times more); 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 Life Support EESA10H3 S Gagandeep Saluja 03/26/2008 • 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 – some mechanisms that will result in breakdown of the certain chemicals inside the adult’s body are not very well developed yet for kids • Kids are growing/developing rapidly, their cells are multiplying faster that is also the difference but as well have a life ahead to live and develop some diseases, to be exposed to certain contaminants and to develop disease for some chemicals may be lifetimes necessary (may be 25-30 years to develop this disease); kids have their whole life to develop this disease • To conclude we see differences in number of cases of the certain diseases; in the past more infectious diseases like bacteria, viral than diseases associated with some infectious agents such as diarrhea • Recently we have seen a switch in this type of diseases in kids on a global scale • Statistics show significant increase in cases of asthma in young children associated with huge number of new substances discovered everyday means everyday more allergens are seen around us and kids are also exposed to them because of their vulnerability and sensitivity, they react more that result in higher cases of asthma for example • Also tendency is increasing in certain types of cancer in children is explained in literature mostly associated with environmental hazards, also increase in some disabilities such as learning disabilities other mental disabilities as well 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; Life Support EESA10H3 S Gagandeep Saluja 03/26/2008 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 boys that is a normal physiological process • Same thing, more fat soluble chemicals women will be more dissolved in fat and more exposed to fat • Women have such great hormones that they live longer and them keep in better health • Subject of the research today is of the two diseases: breast cancer and osteoporosis • Breast cancer (gene, hormones, synthetic chemicals) • Breast cancer is number one – science first found a gene that in about 5% to 10% of women might affect parents of the breast cancer (no more than that) • That might help to find or to recognize the women that have higher risks of getting breast cancer if this gene is found in their genetic material DNA • Also some research connects certain types of hormones with breast cancer • Some other research connects to chemicals such as PCBs; they are also connected with breast cancer but still science does not have a final answer for this, we expect that it will happen very soon finally find a cure for the very deadly cancers • Osteoporosis (fragility of the bones, lead and cadmium role) • Most of the research associated with osteoporosis is in regard to the deficit of calcium in the bones in elder women after menopause when hormones stop doing their job • There is not enough calcium in bones and that will lead to fragility of the bones • Older ladies or seniors can break their bones very easily if they have some symptoms of osteoporosis but many elderly women have this, it is very significant • Some research found the role of the lead and cadmium connected with osteoporosis symptoms • Instead of the calcium, bones can accumulate these types of chemicals during the life women is exposed to relatively high concentrations of the disease that will prevent calcium to be absorbed in the bones Workers and Noise Hazards (Occupation
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