Jan 20

Is mercury making us as mad as a hatter?

“Have I gone mad?” The Hatter asks Alice. “I’m afraid so. You’re entirely bonkers. But I’ll tell you a secret, all the best people are.” replies Alice.

Measurement for environmental protectionPublished in 1865, the enchanting story of Alice’s Adventures in Wonderland features weird and wonderful characters in a world that becomes ‘curiouser and curiouser’. The Hatter is an oft cited favourite among children and adults, with his nonsensical talk and seemingly ridiculous riddles. But was the Hatter in Lewis Carol’s Alice’s Adventures in Wonderland ‘bonkers’ or was he ill – poisoned by his craft?

This is a question that many have pondered, debating whether the character’s eccentricity was due to mercury poisoning. In the 1800s, many milliners suffered mercury poisoning after inhaling vapours when using mercury nitrate to treat the fur of small animals used in the manufacture of felt hats. Prolonged exposure to mercury vapours caused neurotoxic effects including trembling (known as “hatters’ shakes”), loss of coordination, slurred speech, loosening of teeth, memory loss, depression, irritability and anxiety.

Mercury in the home

The use of mercury in the milliner trade has long since ceased, however mercury still poses a global health concern in the 21st Century prompting a tightening of legislation and requiring the efforts of the measurement community – and LGC scientists – to halt rising mercury levels.

Despite its toxicity, mercury appears in our homes and workplaces – found in fluorescent tube lighting, energy saving light bulbs and button cell batteries – and when these products are discarded, mercury pollution can occur.

While there are alternatives to mercury button cell batteries on the market (lithium, silver oxide, alkaline and zinc-air), mercury button cell batteries tend to be cheaper. They are often used in watches, hearing aids, calculators, video game memory cards, camcorders and other electrical devices and, if not disposed of correctly, can end up in landfill where the mercury can leech into soil and water supplies. This, combined with the release of mercury from mining, metal and cement production and the burning of fossil fuels, is having a devastating effect on our environment and, ultimately, could have an adverse impact on our health.

Environmental impact

Aquatic organisms and vegetation in rivers, lakes, and bays convert the less toxic inorganic mercury into toxic, organic methylmercury. When fish eat contaminated vegetation the mercury becomes biomagnified in the fish. The levels of mercury in the shallow ocean layers has tripled since the industrial revolution, according to research published in the journal Nature, which poses a danger to humans as the levels of mercury that we consume by eating fish is also elevated. Current advice from the Food Standards Agency states that pregnant women and women who intend to become pregnant should avoid shark, marlin and swordfish and they may also need to limit the amount of tuna they eat due to the possible risks to the developing nervous system of the unborn child.

In a bid to halt the trend of rising mercury levels, more than 90 countries signed a treaty to limit mercury use and pollution at a United Nations conference in Kumamoto, Japan in 2013. The Minamata Convention on Mercury aims to curb emissions of the metal from power plants and other industrial facilities, and to limit its use in products from batteries and light bulbs and medical equipment.

But for nations to effectively cut mercury emissions, they need to be able to monitor levels of the metal in the environment. A three-year European-funded project involving LGC scientists has been launched to develop the capability of measuring mercury in environmental samples, including biota and air particulates.

LGC scientists work to solve metrological challenges

LGC’s role is to solve outstanding metrological challenges associated with isotope ratio measurements of mercury and mercury species.

Mercury isotopic data can be used to understand mercury amount distribution and environment cycling. This is the way mercury moves through and is re-used or re-absorbed in the environment – not just in terms of geographical location but also what chemical form it’s on (organic or inorganic), which organism it’s in or where else in the environment it is, i.e. river, soil, air.

LGC scientists aim to solve metrological challenges to ensure that sample preparation, introduction and instrumental parameters don’t cause mass discrimination. Special attention will be paid to the evaluation of the potential occurrence of mass-independent effects during sample storage, preparation and analysis.

It will also investigate the feasibility of novel sampling techniques, such as laser ablation, in combination with inductively coupled plasma mass spectrometry (ICP-MS) to rapidly monitor mercury distribution in environmental particulates collected in filters.

If successful, the project will establish the metrological infrastructure for mercury measurements in environmental samples, needed for current and future legislation aimed at controlling mercury emissions and releases. This is just one of the many projects that LGC undertakes in its role as the UK’s National Measurement Institute for chemical and bio-measurement delivering science for a safer world.


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