Toxic Art – Alexander Calder’s Mercury Fountain

As an occupational hygienist, when visiting the Alexander Calder exhibition at Tate Modern last week I couldn’t help but stop and take notice of the pictures and description of one of the works created by this American artist well known for his mobiles and other “kinetic sculptures” . A mercury fountain.

While I was looking at the display, I overheard a comment by a young woman to her partner as they too read about this work

“It couldn’t have been real mercury could it. That would be dangerous”

I couldn’t help responding

“It was, and it is ”

Mercury, the magical Quicksilver, has been known since ancient times. A metal that’s a liquid at room temperature that flows like water.  Being a liquid, vapours are given off which can be inhaled and it can also be absorbed through intact skin. It’s highly toxic, affecting the brain, gastrointestinal system and kidneys. It’s particularly noted for causing neurological and behavioural disorders due to brain damage. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches and cognitive and motor dysfunction. In Victorian times mercury compounds were used in the manufacture of felt for hats and the workers in that industry were particularly affected. This is said to have inspired Lewis Carroll’s “Mad Hatter” from Alice’s Adventures in Wonderland. This was disputed by the esteemed Professor Hugh Waldron back in 1961, but the myth persists.


The exhibition website tells us the story of the fountain’s creation

In 1937 Calder was one of the contributors to the Pavilion of the Spanish Republic designed by Josep Lluís Sert for the International Exposition in Paris, where his Mercury Fountain was installed in proximity to Picasso’s painting Guernica. In the middle of the Spanish Civil War, Calder showed his support for the embattled Republic by creating a fountain that would run with mercury from the mines at Almadén – a valuable economic and strategic resource. (Tate website)

A 2007 study of historical exposures of the workers in Almadén mines to mercury indicated that had been very high

In the mine, the highest exposures occurred during drilling, with values up to 2.26 mg/m3 in air, 2194 μg/l in urine and 374 μg/l in blood. Furnace operation and cleaning were the tasks with the highest values in metallurgy, peaking up to 3.37 mg/m3. The filling of bottles with mercury by free fall gave values within a range of 1.13–2.43 mg/m3 in air; these values dropped to 0.32–0.83 mg/m3 after introducing a new ventilation system.

Occupational exposure limits for mercury are typically set at between 0.02 and 0.03mg/m3

I found it a little ironic that a work of art created in support of a government dedicated to improve the lot of working people celebrated an industry likely to have been responsible for poisoning the workers in the mine where it was extracted.

Although it seems likely that visitors to the exhibition back in the 1930’s would have been exposed to mercury vapours, given the relatively short period that they would have been in the vicinity their exposure would have been limited and its highly unlikely there would have been a significant risk to their health. However, I’d be more concerned about the staff working in the Spanish Pavilion.

Today the fountain can be seen at the Fundació Joan Miró museum in Barcelona – carefully displayed under glass. Hopefully appropriate measures are taken to protect the workers who have to maintain it from the toxic liquid and vapours.

Mercury fountain

Picture from the Fundació Joan Miró museum website


Are the Tate’s sunflower seeds a risk to health?

sunflower seeds 1

Last week I took a short break in London. On Monday we visited the Tate Modern to see the Gauguin exhibition that had recently opened. On arriving at the gallery we noticed that there was something going on in the Turbine hall. We could see that the floor in a large area of the hall was covered with what appeared to be gravel. There were a few people standing and walking on it with some of them taking photos. However, we weren’t allowed access – the area was cordoned off. There were also a number of people on the mezzanine floor wandering around with folders under their arms. I asked one of the gallery attendants what was going on and was told that the “gravel” was a newly installed work by the Chinese artist Ai Weiwei, consisting of 100 million individually handmade ceramic sunflower seeds. According to the Tate press release

Each ceramic seed was moulded, fired at 1300°C, hand-painted and then fired again at 800°C.”

For the first couple of days visitors were allowed to interact with the work – walking  and standing on the “seeds” (we hadn’t been allowed access as it was the press showing when we visited). However, on Friday the gallery announced that  this would no longer be allowed as they had

…  been advised that the interaction of visitors with the sculpture can cause dust which could be damaging to health following repeated inhalation over a long period of time. In consequence, Tate, in consultation with the artist, has decided not to allow members of the public to walk across the sculpture. “

No details have been provided on the risk assessment that led to this decision, but it appears that the seeds can be crushed underfoot generating dust that could become airborne and then inhaled. What could this dust consist of?

Although no exact details are available on the composition of the seeds, porcelain is made from a number of materials that contain crystalline silica. Respirable particles of this common mineral can cause “silicosis” – a serious, debilitating lung disease, where scar tissue is deposited in the lungs reducing their ability to transfer oxygen into the blood and leading to other complications such as emphysema. For the condition to develop exposure has to occur over a long period of time. A single, brief exposure won’t lead to any harmful effects.

A quick search of the literature throws up quite a lot of information on the risk of silicosis during porcelain manufacture, when workers would be exposed to the raw materials, but there does not appear to be much on the hazards presented by inhalation of dust from fired porcelain. Some free crystalline silica is likely to be present, but only as one constituent, and it’s unlikely that all of this will be respirable.

So some of the dust generated by people walking over the seeds may be hazardous, but what really matters is the risk to health. This is determined not only by the hazard, but also the  exposure to the dust, which depends on the concentration and the duration and frequency of exposure.

Risk = hazard x level of exposure x duration x frequency

Even if all the dust did consist of respirable crystalline silica,  I think that it is unlikely that the risk to visitors would be significant. Its difficult to estimate what the dust concentration would be, but as the Tate themselves state, the dust “could be damaging to health following repeated inhalation over a long period of time”. Most visitors from outside London are probably only likely to visit the exhibition once and would perhaps spend a couple of hours in the Turbine Hall. Even if the concentration of crystalline silica was above the Workplace Exposure Limit (which is probably unlikely) their exposure would not constitute “repeated inhalation over a long period of time”.

Perhaps the concerns are for the health of the staff who work in the gallery (although that is not what the Tate are saying). They clearly would have a longer and more frequent exposure to the dust. The risk then, would depend on the concentration of the dust in the Turbine Hall. I don’t know whether the Tate have properly assessed this, but it would be relatively easy to monitor the dust levels to allow an informed judgement to be made of the risk.

It is possible that there are other components of concern in the dust. The seeds are all painted and paint pigments can contain toxic materials. I would have hoped that the artist would have avoided using such paints due to the potential risks to the artisans who created the seeds for him. However, even if the pigments did include toxic components the same considerations would probably apply as for the respirable crystalline silica – i.e. the risk would be from repeated exposure to a significant concentration over a long period of time and, as with the silica, it is unlikely that this would be the case, certainly for visitors.

It seems likely that the Tate have overreacted somewhat. I think the health risk to visitors due to exposure to any dust will be negligible. So this could be a case of “health and safety gone mad” or perhaps the Tate have other reasons for forbidding visitors from walking on the work.

Photo credit : arkadin55

Further information on silica hazards and control of risks are available from


UK Health and Safety Executive