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Chemical culprits

Martin Mittelstaedt
wrote an article in the Globe and Mail (F4, 20 September, 2008) on the dangers
of chemicals and the ramifications on human birth rates. The article
highlighted some chemicals which have been proven to have an adverse effect on
human physiology, particularly the male reproductive system.


Chemical culprits

By some counts, nearly a hundred man-made chemicals
either act like hormones or interfere with them, but scientists highlight four
as major worries:

Bisphenol A, or BPA, the polycarbonate-plastic and
tin-can-lining chemical, has been found in experiments by Frederick vom Saal
and others to cause prostate abnormalities and other developmental changes
linking to sex hormones in laboratory animals, at levels around and below
currently accepted safety standards.

Phthalates (pronounced THA-lates), a family of
chemicals used to make polyvinylchloride plastic more pliable, are found in
everything from shower curtains, new car interiors to perfumes. It inhibits
testosterone synthesis by interfering with an enzyme needed to produce the male
hormone. Phthalates aren’t embedded in products through strong chemical bonds,
making them vulnerable to leaching out.

Polybrominated diphenylethers, or PBDEs, are flame retardants
used in plastics, foams and electrical equipment. They are able to interfere
with thyroid hormones, which are essential for proper brain and testicle
development, and have been linked in animal research to attention-deficit-like
conditions.

Polychlorinated biphenyls, or PCBs, are now-banned
transformer-oil fluids widely used up to the early 1970s. They have a similar
molecular shape to flame retardants and reduce thyroid hormone levels. Research
has linked low PCB exposures to reduced impulse control and lower intellectual
capacity in children. The most recent study, published in Environmental Health
Perspectives in May, found that a mere one-part-per-billion increase in PCB
concentration in a baby’s placenta was associated with a three-point IQ drop at
the age of 9.

Martin Mittelstaedt

Source: Globe and Mail