The Naked Scientists

The Naked Scientists Forum

Author Topic: How common are they? Endocrine Disrupting Chemicals (EDCs)  (Read 5476 times)

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11999
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
This is lended from another site.
I just put in some links, as if it is true it do seems worrying.

So, is it true?

===Quote

Isphenol A (BPA) is a ubiquitous compound in plastics. First synthesized in 1891, the chemical has become a key building block of plastics from polycarbonate to polyester; in the U.S. alone more than 2.3 billion pounds (1.04 million metric tons) of the stuff is manufactured annually.

Since at least 1936 it has been known that BPA mimics estrogens, binding to the same receptors throughout the human body as natural female hormones. And tests have shown that the chemical can promote human breast cancer cell growth as well as decrease sperm count in rats, among other effects. These findings have raised questions about the potential health risks of BPA, especially in the wake of hosts of studies showing that it leaches from plastics and resins when they are exposed to hard use or high temperatures (as in microwaves or dishwashers).

The U.S. Centers for Disease Control (CDC) found traces of BPA in nearly all of the urine samples it collected in 2004 as part of an effort to gauge the prevalence of various chemicals in the human body. It appeared at levels ranging from 33 to 80 nanograms (a nanogram is one billionth of a gram) per kilogram of body weight in any given day, levels 1,000 times lower than the 50 micrograms (one millionth of a gram) per kilogram of bodyweight per day considered safe by the U.S. Environmental Protection Agency (EPA) and the European Union's (E.U.) European Food Safety Authority (EFSA).

Studies suggest that BPA does not linger in the body for more than a few days because, once ingested, it is broken down into glucuronide, a waste product that is easily excreted. Yet, the CDC found glucuronide in most urine samples, suggesting constant exposure to it. "There is low-level exposure but regular low-level exposure," says chemist Steven Hentges, executive director of the polycarbonate / BPA global group of the American Chemistry Council. "It presumably is in our diet."

BPA is routinely used to line cans to prevent corrosion and food contamination; it also makes plastic cups and baby and other bottles transparent and shatterproof. When the polycarbonate plastics and epoxy resins made from the chemical are exposed to hot liquids, BPA leaches out 55 times faster than it does under normal conditions, according to a new study by Scott Belcher, an endocrine biologist at the University of Cincinnati. "When we added boiling water [to bottles made from polycarbonate] and allowed it to cool, the rate [of leakage] was greatly increased," he says, to a level as high as 32 nanograms per hour.

A recent report in the journal Reproductive Toxicology found that humans must be exposed to levels of BPA at least 10 times what the EPA has deemed safe because of the amount of the chemical detected in tissue and blood samples. "If, as some evidence indicates, humans metabolize BPA more rapidly than rodents," wrote study author Laura Vandenberg, a developmental biologist at Tufts University in Boston, "then human daily exposure would have to be even higher to be sufficient to produce the levels observed in human serum."

and this....

Every male fish in some European rivers shows pronounced female characteristics, according to Professor Alan Pickering of the Natural Environment Research Council. Speaking to the British Association's Festival of Science in London earlier this month, Pickering said, "We are finding this problem right across northern Europe, it is clearly widespread."

Pickering said that "It seems to relate to a mixture of chemicals both industrial and also some of the natural excretory products from the human body." These substances, known as endocrine disrupting chemicals (EDCs) or “gender-benders”, are found in some agrochemicals, paints, oils, toiletry products and detergents. They mimic the hormones produced by the female ovaries and the male testes in animals, which regulate growth and reproduction.

It remains unclear exactly what estrogen-mimicking chemicals were actually present in the fish and what kind of cancer-causing role they might have. But their effects on the fish themselves were clear: the gender of nine of the fish could not be determined. "Increased estrogenic active substances in the water are changing males so that they are indistinguishable from females," Volz says. "There are eggs in male gonads as well as males are secreting a yolk sac protein. Males aren't supposed to be making egg stuff."

== End of quote_

Power point presentation. USA. and England. And Prof. Alan D. Pickering. NERC Centre for Ecology and Hydrology.

"The bad thing is this doesn't even cover the massive island of plastic (the size of texas)
floating around in the pacific......plastics breakdown quickest when exposed to sunlight but take a great deal longer under ground."


 

Offline ibrahimf

  • First timers
  • *
  • Posts: 1
    • View Profile
Science Research Question: Causes of low sperm count?


Paragraph 1

   There are many reasons for why males have low sperm count. During my research on Google and Twitter, I search the keywords, “Causes of low sperm count.” Low sperm count can be caused by biological reasons: Infections, cancer/diseases, issues with ejaculation, hormonal imbalances, chromosome defects can cause low sperm count. Other reasons could be environmental: Exposure to harmful chemicals, metal, radiation, or overheating in the nether regions. Some can be caused by lifestyle choices; what males put into their body: Drugs, alcohol, smoking, and diet can all affect sperm cell motility. 


Paragraph 2

   What I found interesting during my research was the environmental causes and a little interest in the biological causes. An example for an environmental cause for low sperm count is overheating. For example, if males wear tight pants/trousers, have their laptops on the laps for an excessive period of time, or take a hot shower/bath, it heats the scrotum, which could damage their sperm cells and lower their sperm cell count. Another example can be males who have had a cancer related experience in which they had to go through radiation therapy. Radiation can lower sperm cell count permanently, and in some cases after radiation therapy, it can take years before their sperm cells to develop normally.
« Last Edit: 27/04/2014 04:13:02 by ibrahimf »
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8669
  • Thanked: 42 times
    • View Profile
"The U.S. Centers for Disease Control (CDC) found traces of BPA in nearly all of the urine samples it collected in 2004 as part of an effort to gauge the prevalence of various chemicals in the human body. It appeared at levels ranging from 33 to 80 nanograms (a nanogram is one billionth of a gram) per kilogram of body weight in any given day, levels 1,000 times lower than the 50 micrograms (one millionth of a gram) per kilogram of bodyweight per day considered safe"
So, if there were 1000 times more of it, it would still be safe.


Why would you consider that "truly worrying"?
 

Offline dlorde

  • Neilep Level Member
  • ******
  • Posts: 1441
  • Thanked: 9 times
  • ex human-biologist & software developer
    • View Profile
...
So, if there were 1000 times more of it, it would still be safe.

Why would you consider that "truly worrying"?
Read further on in that post, and it says:
Quote
A recent report in the journal Reproductive Toxicology found that humans must be exposed to levels of BPA at least 10 times what the EPA has deemed safe because of the amount of the chemical detected in tissue and blood samples. "If, as some evidence indicates, humans metabolize BPA more rapidly than rodents," wrote study author Laura Vandenberg, a developmental biologist at Tufts University in Boston, "then human daily exposure would have to be even higher to be sufficient to produce the levels observed in human serum."
What is truly a concern is that the two sets of figures are several orders of magnitude apart, which suggests a major snafu somewhere...
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8669
  • Thanked: 42 times
    • View Profile
No, it just suggests different assumptions.
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums