The International Agency for Research on Cancer classifies
acrylamide as a probable human carcinogen. It has only been in recent
months that an epidemiologic study first found a link between dietary
acrylamide and human cancer risk. Now Danish researchers report that
acrylamide adduct levels in blood are associated with an increased risk
of breast cancer in postmenopausal women.
Before the 1924 advent of salt iodization, millions of Americans
suffered from iodine deficiency. Now, eight decades after salt
iodization virtually eliminated iodine deficiency in the United States,
intake of this essential mineral has once again declined enough for
some scientists to recommend new measures to ensure Americans get
sufficient amounts.
The thyroid gland need iodine in order to produce
thyroid hormone, which regulates body metabolism, growth, and
development. Iodine is especially important during pregnancy and
lactation for infants' neurological development. Maternal iodine
deficiency is associated with mental retardation and cretinism in the
newborn.
In the first National Health and Nutrition
Examination Survey (NHANES I), conducted in the early 1970s, only 1% of
pregnant women examined had urinary iodine levels below 50 µg/L
(although this level suggests moderate deficiency, it is impossible to
ascertain deficiency from a single urine sample). By the time of the
2000–2001 NHANES, 7.3% of pregnant women had urinary iodine values
below 50 µg/L.
Where did all the iodine go? According to the
Virginia-based Salt Institute, only 20% of food salt is iodized today,
and most of that is sold at grocery stores. Salt iodization is
voluntary in the United States, and Morton Satin, president of the Salt
Institute, says most food processors and restaurants never adopted
iodized salt because it wasn't required. As Americans have embraced
processed foods and restaurant meals, noniodized salt has supplanted
the iodized type in many people's diets. Satin says his organization
has publicly asked the food and restaurant industries for broader
iodization. Iodine was also used at one time in dairy products and
bread, but has been replaced with more effective alternatives.
Purnendu Dasgupta, a biochemist at The University
of Texas at Arlington, published research in the 15 February 2008 issue
of
Environmental Science & Technology
showing that 53% of iodized salt samples tested had lower iodine levels
than recommended by the U.S. Food and Drug Administration. The study
also revealed that exposure to high humidity diminishes iodine in salt.
The possibility of asymptomatic iodine deficiency
during pregnancy is raising concern. "I think it's quite likely we've
had subtle neurological deficiencies in babies born in the U.S. [to
mothers with mild iodine deficiencies]," says Elizabeth Pearce, an
assistant professor of medicine at Boston University School of
Medicine. To protect developing fetuses, Pearce and other scientists
are calling on the government to boost Americans' iodine intake. "I
wouldn't endorse greater salt intake," says thyroid specialist Robert
Utiger of Harvard Medical School, referring to salt's association with
hypertension, heart disease, and stroke. "But the iodine content of
salt ought to be increased."
Since 1994, the World Health Organization has
recommended universal salt iodization to combat deficiency. Says Satin,
"One approach would be to adopt the strategy being employed in New
Zealand. They are taking measured steps in specific food categories and
can keep adding [iodization to] additional food categories as
monitoring dictates." Kevin Sullivan, an associate professor of
epidemiology at Emory University in Atlanta, says that if food
processors adopt iodized salt we should closely monitor iodine levels
through ongoing NHANES studies to see if iodization recommendations
need to be adjusted.
Another approach is to require iodine in all
prenatal vitamins. Although the American Thyroid Association has
promoted such a measure since 2006, Pearce says only an estimated 50%
of prenatal vitamins contain iodine.
Says Dasgupta: "Some believe that iodine
deficiency is a disease of the past that was 'cured' in the 1930s with
the iodization practices. This leads to the thought today that
iodization is not needed because it was cured, but the fact is that it
is a deficiency disorder, not a disease."
originally published on http://www.ehponline.org
