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Lecture 5

Week 5 Lecture

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Environmental Science
Jovan Stefanovic

Chemical Hazards and Human Health Chemical Hazards • l Endocrine disrupters (we produce hormones in our bodies that perform very important functions – reproductive or sexual functions) • l Chemical body burdens – chemical pollutants mimics hormones, as a result these chemicals disrupt the normal function of the hormone Data mostly from animal studies, not much from human exposure Endocrine disrupters 1. Direct effects: • Bind to hormone receptors = carry hormones in the body • Alter the appearance of some genes (genes may change) • Changes in the level of produced proteins 2. Indirect effects: • Altering hormone production (amount/level of hormones changes) • Altering hormone transport • Altering hormone metabolism Fetus more sensitive than adults – health problems in adults can result in recovery or not permanent, however in fetuses they may be permanent and affect their whole life DES (diethylstilbesteol) = something that’s been prescribed as synthetic hormone • l Synthetic estrogen used by physicians to prevent spontaneous abortion (1948-1971) • l Administered for early pregnancy until 35 weeks • l > 1million women took it between 1960-1970 • l Daughters whose mothers took DES have increased incidents of: o l Reproductive organ dysfunction o l Abnormal pregnancies o l Reduction in fertility o l Immune system disorders o l Carcinoma o Cancer Endocrine disrupters - Health Implications • l Feminization of males • l Abnormal sexual behavior • l Birth defects • l Altered time to puberty • l Cancer of mammary glands or testis • l Thyroid dysfunction Endocrine disrupters – Neurobehavioral effects (destruction in mental development, low IQ, learning disabilities later and later in life) • l Prenatal and early postnatal exposures • l PCBs (poly chlorinated bi contaminants): o l Impaired learning in nonhuman primates o l Delayed psychomotor development o l Distractibility o l Poor IQ tests o l Organophosphates - Brain development Chemical body burdens • l Quantity of chemicals accumulated in the body (started before you were born, through breast milk, air, water, food you consume…etc.) • It’s everywhere and everybody has a high quantity of chemicals accumulated in the body • There are thousands of chemicals already, and every year there are thousands of new chemicals o l Not stable over time (level of chemicals change over time in the body) o l Not distributed homogeneously/evenly in a body o l Not possible to detect if present in very low concentrations (our knowledge is limited) We are not aware of the new chemicals in our bodies, have no idea they exist o l Biomonitoring – “normal level” = chemical body burden level is higher than normal Organochlorine Substances (the most famous ones:) • l Dioxins • l DDT Dioxins (a group of chemicals) • l Dioxins have no commercial usefulness by themselves • l Formed during o l combustion process such as waste incineration, forest fires and backyard trash burning o l manufacturing processes such as herbicide manufacture and paper manufacture Dioxins • l Group of chemical compounds with similar chemical structure • l One of the most toxic and most studied is 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) • The more chlorines there are, the more toxic it is Dioxins • l In food • l Very slowly removed from the body (POP-persistent organic pollutants) • l Accumulate in fat tissue (soluble in fats) A chart illustrating how much dioxin the average American (USA) consumes per day. (Note: pg = picogram, or one trillionth of a gram) • The fatty foods contain more dioxins than the less fat Dioxins – destruct hormone function in your body • l Affect cells in similar way as hormones such as estrogen o l Binds to a protein (Ah receptor) present in cells o l Then receptor can bind to DNA and alter the appearance of some genes o l This can lead to changes in the level of specific proteins and enzymes in the cell Dioxins • l At low levels- Effect of constant exposure to low levels is not known • l Focal point for ongoing research (the molecular and cellular mechanisms) • l At high levels very toxic o l cause cancer in laboratory animals and humans, mechanism is not known o l alter reproductive, developmental and immune functions o l increased heart disease and diabetes o l immune suppression o l study in mice showed ability to cause birth defects (teratogenicity) Chloracne = changes on skin • l Victor Yushchenko – President of Ukraine before and after di
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