Mini Med School VIII - Epigenetics
Are these hormones organic Q & A
Q: Dioxin - Is there still dioxin produced by auto exhaust? If so, how pervasive and potent is this in our food-chain? (e.g. dioxins in our fruits & vegetables, in the food that domesticated farm animals ingest, etc).
A: Any and all combustion reactions will produce some level of dioxin. Since chlorine is limiting, dioxin production is minimal and overall is a minor source of dioxin in our food chain.
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Q: When speaking of estrogen mimickers, does that include estradiol, estrione, and estriol? Which is of the most concern?
A: Esdradiol, estrione and estriol are endogenous or naturally produced estrogens synthesized in the body and therefore are not considered endocrine disruptors. The greatest concern is chemicals and drugs that mimic the activity of endogenous estrogens like 17beta-estradiol. Some scientists are also concerned about natural estrogenic chemicals in food such as genistein in soy and resveratrol in red wine.
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Q: Do levels of estrogen and testosterone affect intelligence? Just on a general scale, I've noticed women with more "development" do not excel in the sciences, as do homosexual men; whereas men tend to excel in the sciences as do women with increased testosterone levels. Is this a connection with competitiveness and aggression or perhaps the expression of genes that deal with interpretation of information?
A: Estrogen and testosterone do influence behavior and have neuroprotective properties. This would include competitiveness, aggression, nurturing behaviors. However, I am unaware of any association between estrogen and testosterone to intelligence.
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Q: In the lecture, we learn about exogenous agents that alter the production of estrogen (i.e. fish taking on female attributes due to birth control pills). Are there any exogenous agents that affect male sex hormones? Any agents that make females become more masculine?
A: There has been little research on androgenic endocrine disruptors. However, there have been reports of endocrine disruptors that block the activities of testosterone which would result in a feminization of males. I do not know of any examples of endocrine disruptors (chemicals or natural products found in fruits, vegetables or other plants) that masculinize females.
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Q: If a developed male fish is exposed to estrogen over a period of time and changes sex, can it still reproduce successfully as a female? Or does it just "look" female? If it does turn into a female, what happens to the developed male structures? Can you reverse the process?
A: The reproduction of a feminized male is usually compromised to the point that it can not successfully reproduce. In addition to sperm maturation being disrupted, there are also disruption of secondary sex characteristics, and mating behaviors.
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Q: Are the chemicals in lotions, shampoos, etc the sodium lauryl sulphates that are often cited as "bad" and if so, are they bad?
A: There is concern regarding some chemicals in shampoos and other personal care products - more specifically nonylphenols and phthalates as well as some antioxidants - due to studies indicating they elicit endocrine disrupting activities in rodent studies at high doses. At this time, I am unaware of other oils and fats added to personal care products that have endocrine disrupting activity.
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Q: Are the industrial endocrine disruptors discovered today mostly modern compounds? If not, wasn't there major environmental harm on animals during the industrial revolution?
Dr Tim Zacharewski
A: The effects that are of concern today are more subtle and may be a result of a higher level of exposure to these chemicals to a much larger population. During the industrial revolution our stewardship of the environment was not as closely monitored and not regulated by laws that companies need to abide by today. Consequently, many industrial endocrine disruptors are high production volume chemicals that are used in various facets of modern life.
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Q: Is there any influence of parents' workplace on the gender of a new-born baby? In employees' children, at certain workplaces, the genders have always been the same.
Dr Tim Zacharewski
A: There have been some reports of exposure to endocrine disruptors skewing gender ratios in favour of females but this has been associated more with an area as opposed to a workplace or occupation. For example, there were reports that the Great Lakes region had more female births than male births relative to other regions in the US that was attributed to dioxins ands related organochlorine chemicals (e.g., PCBs). The effects are again subtle therefore you need a large number of people to do the study so it is unlikely that there would be sufficient statistical power to do similar studies examining specific occupations.
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