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| Is there mercury in your mascara? |
16 days ago, the United Nations’ Minamata Convention for
Mercury was signed by about 140 countries. Among other measures to reduce the
use of mercury, this global treaty specifies that the production and import of
some products containing mercury will be banned.
‘Under a new global
treaty that limits the use of mercury, some light bulbs will be banned. Some
batteries, thermometers and medical devices will be banned too. But mascara is
exempt.’
The reason is then explained:
‘But mascara and
other eye makeup is exempt because “no effective safe substitute alternatives
are available” and “the intention is not to cover cosmetics, soaps or creams
with trace contaminants,” the treaty says.’
Not surprisingly, this news has sparked quite an outrage.
What? Do you mean we have been applying
mercury around our eyes? How can this continue to be allowed?!
So… Why does
mascara contain mercury?
Some mascara products (as well as other products such as
eyedrops & vaccines) may contain mercury in the form of thiomersal, which
is used as a preservative. Thiomersal is an organomercury compound which contains
approximately 50% mercury by weight.
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| Chemical structure of thiomersal |
The US FDA allows mercury in eye cosmetics at a limit of
65 parts per million (which is 0.0065%, in case anyone was wondering).
As a preservative, thiomersal inhibits the growth of
bacteria and fungi which can spoil the products and also lead to nasty eye
infections.
What harm do
mercury compounds cause?
The world became aware of the toxicity of methylmercury in
the late 1950s, when the dumping of methylmercury into Minamata Bay, Japan by a
local petrochemical and plastics company resulted in widespread consumption of
mercury-contaminated fish and shellfish. The consequences were devastating. Methylmercury
proved to be a neurotoxin (affecting the nerves and brain) and led to illness,
foetal abnormalities and death.
Currently, the US Environmental Protection Agency has set
a reference of 0.1 µg/kg/day as a guideline for safe exposure levels to
methylmercury.
Much less is known about thiomersal, which is a
derivative of ethyl mercury. An
animal study by Magos et al. in 1985 directly compared the toxicity of ethyl-
versus methylmercury in adult male and female rats. Ethylmercury was concluded
to be less neurotoxic than methylmercury. Regardless, due to the lack of data, the
FDA considers ethyl- and methyl-mercury to be equivalent in its risk evaluation.
Is it possible to
avoid mascara and eye products containing mercury?
According to the article by Scientific American,
‘The FDA does not
require ingredients that comprise less than 1 percent of a cosmetic product to
be divulged on the label, so a lot more products may have thimerosal and
consumers would never know, said Kristin Adams, chief executive officer of
Afterglow Cosmetics, a natural and organic cosmetic company.’
This afternoon, I did a quick survey of the ingredient
labels of a few mascara products at the drugstore. Some products contained
phenoxyethanol and parabens (both are preservatives) as ingredients. Some other
products did not specify any preservatives on their labels. Does this mean what I think it means?
Clearly, all mascaras SHOULD contain
preservatives (to prevent eye infections), but the preservatives are not
necessarily listed on the label because their concentrations are very low. Kristin Adams was right.
To put things into
perspective,
There are many other possible ways that we could be
exposed to mercury. For example, eating contaminated fish (which is the most
significant source of ingestion-related mercury exposure), taking some Traditional
Chinese Medicine preparations, or even accidentally breaking a lab thermometer.
With the signing of the Minamata Convention for Mercury treaty, we can hope to
look forward to a reduction of mercury contamination in the environment.
