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

Information on hazardous substances–some useful websites

There is a lot of information on hazardous substances the Internet, but not all of it is properly validated. Finding the information you need just by carrying out a search using a search engine can be frustrating as it can be difficult to sort the wheat from the chaff. However, there are a number of good quality online databases that can be accessed free of charge on the Internet. These are some that I find particularly useful


The US National Library of Medicine’s Toxicology and Environmental Health Information Program (TEHIP) operates TOXNET®, an integrated database system of hazardous chemicals, toxic releases and environmental health.

Particularly useful are

ChemIDplus – A dictionary of over 370,000 chemicals (names, synonyms, and structures) which also includes links to other databases and resources.

Hazardous Substances Data Bank (HSDB) – A databases containing comprehensive, peer-reviewed toxicology data for about 5,000 chemicals.

TOXLINE – A bibliographic database containing references from the toxicology literature. In most cases abstracts are included and they often provide enough information for a practising occupational hygienist.

Other databases on TOXNET® have information on carcinogenicity and mutagenicity test results, genetic toxicology test data and chemicals that can present a developmental and reproductive hazard

ECHA C&L Inventory database

The Classification and Labelling Inventory database, run by the European Chemicals Agency, contains classification and labelling information on notified and registered substances received from manufacturers and importers. It also includes the list of harmonised classifications. The database is refreshed regularly with new and updated notifications.

IFA Databases

The German Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA, Institute for Occupational Safety and Health of the German Social Accident Insurance) has a number of very useful databases. These include

GESTIS – International limit values for chemical agents Occupational exposure limits (OELs)

This database contains occupational exposure limit values for about 1,700 substances, from various EU member states, Australia, Canada (Ontario and Québec), Japan, New Zealand, Singapore, South Korea, Switzerland, and the United States as of March 2012.

It can be viewed online and is also available as app for iPhone, iPodtouch, iPad and Android


A DNEL – or Derived No-Effect Level – are used as part of the REACH risk assessment process and are defined as

“the level of exposure to the substance above which humans should not be exposed”.

The GESTIS DNEL Database provides workplace-related DNELs which have been established by manufacturers and importers under their own responsibility and have been published by the European Chemicals Agency (ECHA)

The database can be viewed online or downloaded as an excel spreadsheet.

GESTIS-database on hazardous substances

A database with information on approximately 8000 substances, including chemical and physical properties, basic toxicological data, advice on handling and first aid information.

Organic compounds – Health hazards


We’re running the BOHS Module W507, Health effects of hazardous substances, in Chester next week. It’s essentially an introduction to the principles of toxicology together with an overview of the effects of some substances encountered in the workplace.

One group of substances commonly found are volatlile organic compounds (VOCs). They’re used for cleaning applications and as solvents in a wide range of products such as fuels, paints, inks and adhesives. They can be supplied on their own (e.g. trichloroethylene used for vapour degreasing ), or as blends or mixtures (e.g. white spirit, petrol etc.).

The main route of absorption for solvents is via inhalation,  due to their volatility.  But skin exposure is important too. VOCs can affect the skin itself and many can be absorbed through intact skin and absorbed into the bloodstream; with some compounds, this can be a major route of entry into the body.

Environmental legislation has led to a reduction in the amount of VOCs used, but according to the latest statistics from DEFRA, in 2012 there were about a 750,000 tonnes of VOCs emitted to atmosphere in Great Britain.

There are many other less volatile organic compounds used in industry. And some of these, such as diisocyanates, epoxies and organophosphates can have serious impacts of human health.

As one of the new International Modules, the exam for W507 is open book. This means that, unlike the previous equivalent British Module M101, it isn’t necessary to memorise a large volume of facts to pass. In the real world occupational hygienists don’t need to be “walking encyclopaedias” as there are plenty of valid resources that can be used to look up details for less common substances. Although I do think good occupational hygienists will know the effects of the more important “common” substances, particularly the ones they’re likely to encounter in the workplace, such as VOCs.

The following Slideshare presentation provides an introduction to the effects of common organic compounds. You’ll learn more if you attend the course!

Frustrated phagocytes and the fibre paradigm

These were a couple of phrases from Rosemary Gibson’s presentation during the nanotechnology workshop during the recent BOHS Conference.

The fibre paradigm sets out the basis for the harmful effects caused by resistant fibres such as asbestos.  It states that fibres will damage the lung if they are

  • thin enough to enter the lungs
  • longer than the phagocytes that clear particles from the lungs
  • resilient and non-biosoluble, so that they remain in the lung

The long thin fibres that deposit and remain in the lung can’t be engulfed by the phagocytes, so that the ends of the fibre protrude from the cell.  The phagocye is said to be “frustrated”

t012365a-macrophages-on-an-asbestos-fibre1 (1)

This results in the release of chemicals that cause damage to the lung tissue leading to inflammation and, subsequently, to other damage, including the deposition of scar tissue (fibrosis).

Potentially any fibre which is thin enough to travel down to the alveoli and too long for the phagocyles to deal with it effectively could cause this to occur.  However, fibres that are biosoluble break down and can be cleared from the lung before significant damage can occur. So some materials, such as glass fibre, are deliberately formulated to dissolve in the body. Other, more resilient, fibres such as asbestos, remain in the lung long enough to allow the process to occur.

Recent research has suggested that some of the new engineered nano-materials, such as long carbon nanotubes, can cause effects similar to asbestos as their structure and dimensions means that they conform to the “fibre paradigm”

Source: Donaldson et al. Particle and Fibre Toxicology 2010 7:5

There’s a good summary of the fibre paradigm in an open access paper by Donaldson et al. published in the journal Particle and Fibre Technology last year, which is available on the web here.

BOHS Conference workshop on nanotechnology

Titanium dioxide nanoparticles

In her Keynote address to the 2011 BOHS Conference, the Chair of the HSE, Judith Hackitt, mentioned nanotechnology as one of the “emerging issues” that HSE will continue to give priority to despite the cutbacks in its budget. Nanotechnology has been a high profile issue for HSE for a number of years as the production of “engineered” nanoparticles has increased. Their toxicology isn’t fully understood and measurement presents a number of problems, so it is difficult to properly evaluate the risks to health.

At last year’s conference, a plenary session was devoted to nanotechnology and this year it was the theme for one of the workshops. It was a good session, with three speakers covering health effects, assessment and control. However, the content of their talks was very similar to those given during the plenary sessions last year, suggesting that there haven’t been any major advances in the science over the past 12 months.

Rosemary Gibson form HSL made a very good presentation summarising the health implications of engineered nanoparticles. The key points she made included

  • Nanoparticles have a very large surface area to volume ratio and this has implications for their effects on health. Some researchers have identified a relationship between surface area and inflammation and this suggests that surface area is the best metric to use to assess the risk, rather than mass concentration (which is normally used with particulates).
  • Research has mainly focused on their effects on the respiratory system with some work on skin effects. Less work has been carried out on systemic effects. However, the main concern identified from experience with ultrafine particulate air pollutants (from non-engineered sources such as diesel exhaust emissions) is effects on the cardiovascular system, and some research has suggested that this is also relevant with engineered particles, so more work is needed on this aspect.
  • There are continuing concerns about the effects of carbon nanotubes and whether these fine, fibre like particles may behave like asbestos. Work by Poland et al, the results of which were published n 2008, certainly suggest that this may be the case with long multiwalled carbon nanotubes, where there was evidence of inflammation and granulomas. However their research also suggested that short multiwalled carbon nanotubes were non-harmful. (For further details, see the commentary by Ken Donnaldson, here).

The other two speakers, James Wheeler of the HSE and John Hulme of Cambridge University (who gave a Keynote on Nanoparticles at last year’s conference) both concentrated on practical implications in the workplace.

James emphasised the need for a sensible approach to risk management. Precaution was needed, as nanotechnology was a “step into the unknown”, but he emphasised that the risks could be managed and controlled in the same way as high hazard materials, using the principles of good practice embodied in the COSHH Regulations. HSE has a website on nanotechnology and has also issued guidance on carbon nanotubes. Further guidance, produced in conjunction with relevant partners, should be available in March 2012

John, who has considerable experience of managing the risks from nanoparticles in research laboratories at Cambridge University, concentrated on the practical assessment and control of the risks. He pointed out that the hazard information provided by some suppliers of nano-materials was inadequate, treating them as if they were no different from macro forms of the substance when there were clear differences in toxicology. He re-emphasised one of the points Rosemary made about the importance of surface area and discussed the practical difficulties of measurement.  Methods are available to measure particles on the basis of their surface area, but as these techniques can’t identify what the particles are it isn’t possible to tell where they have originated. There can be high background levels of fine particles from natural and man-made sources, which confuse the results from any surveys. So the problem with nanoparticles is that we aren’t sure of the hazards and can’t properly quantify the risk!

John’s answer was that we need to take a precautionary approach and control all potential exposures to a high standard. He provided some good examples from his experience of controls that can be applied in practice including:

  • preventing particles becoming airborne by using slurries rather than powders
  • working in glove boxes and microbiological safety cabinets
  • applying well designed local exhaust ventilation, pointing out that nanoparticles behave like gases and so are easy to capture
  • using HEPA filters to minimise emissions to the environment and workplace

For further information on nanotechnology hazards and control see

HSE nanotechnology website

HSE guidance on carbon nanotubes

Safenano website

Image credit :

Pollution and human health

For a number of years now, in November / December I’ve contributed to an MSc in Pollution and Environmental Control, delivering a couple of lectures covering “Pollution and human health”.

People can be exposed to pollutants by inhalation of air pollution, and ingestion of polluted water or foodstuffs. Their effects on human health can be

  • Direct – where the pollutant causes direct harm to the individuals exposed
  • Indirect – where the effects of the pollutant on the environment and the resulting changes, can affect human health. Climate change, caused by the accumulation of carbon dioxide in the atmosphere due to human activity, can lead to health effects due to the increase in temperature (increased temperatures can lead to increased mortality in vulnerable groups, such as the elderly) and associated environmental impacts (drought, sea level rise etc.)

According to the World Health Organisation, an estimated 24% of the global disease burden and 23% of all deaths can be attributed to environmental factors. They estimate that in 2004  these resulted in a total of 5,309,000 deaths, the overwhelming majority from low income countries. (World Health Organisation 2006). However, richer countries are also affected, particularly by air pollution.

I’ve uploaded my presentation to Slideshare, and they can also be viewed below.

The poison garden

I’ve just got back from a week’s holiday in Northumbria. It’s a region I haven’t visited previously I’ve never got past Newcastle before. It’s a very beautiful area with a fantastic coastline and lots of historic monuments to visit.

One of the places I visited during my trip was Alnwick Castle and Gardens. The gardens were redesigned only 10 years ago by Jacques and Peter Wirtz and provide a contemporary take on the traditional stately home estate.

One part of the gardens I found particularly interesting was the “Poison Garden“.  This contains a collection of  “poisonous” plants locked away behind a gate and which can only be accessed when accompanied by a guide. The collection included opium poppies, cannabis and the coca plant, for which the Alnwick Garden Trust had to obtain a special licence. However, most of the plants on display could be found in the countryside or domestic gardens. They included some obvious harmful weeds such as nettle and giant hogweed, well-known poisonous plants such as, belladonna and wormwood, but also decorative plants such as laburnum, willow and even some foodstuffs, including rhubarb.

The message that came across during the tour is one that occupational hygienists should be familiar with – everything is poisonous if we absorb enough of it and that even plants we consider harmful have their beneficial uses.

The opium poppy produces the highly addictive and harmful drugs opium and heroin, but it’s also used to produce morphine which is used to relieve severe pain. Of course morphine is addictive and uncontrolled doses are lethal (and the infamous G.P.  Harold Shipman used it to murder his patients) – a clear case of the dose “differentiating a remedy from a poison” .

Opium poppies

Laburnum have attractive yellow flowers and pea-like pods and are very popular garden trees. However all parts of this plant, – the roots, bark, wood, leaves, flower-buds, petals, and seedpods – are toxic, containing cytisine. There are hospital admissions every year, normally where children have eaten the pea-like seeds from the tree. But the tree is probably planted in hundreds of thousands of gardens around the country and very few of them cause harm – this can only occur if someone ingests the toxin.

I don’t know how popular rhubarb is these days, but I certainly enjoy this tart fruit. Yet here it was planted up in the poison garden.  The part of the plant we eat is the stalk. The leaves, however, contain  oxalic acid in the form of oxalates and anthraquinone alkaloids. Contrary to popular belief, it’s the latter, rather than the former that are the cause of harmful effects when the leaves are eaten.

Its risk that matters – the likelihood of the harm occurring –  and even the most toxic substance can’t cause harm in practice if it isn’t absorbed. So we can have laburnum trees in our gardens and grow and eat rhubarb providing we don’t ingest those parts of the plant containing the toxins. Even if we do, death doesn’t necessarily result – the effects we experience depend on how much we absorb. Similarly highly toxic chemicals can be used in the workplace without anyone being adversely affected if exposure is adequately controlled.

As Paracelsus noted many years ago

“All substances are poisons ; there is none which is not a poison. The right dose differentiates a poison from a remedy”

The poison garden at Alnwick is a good illustration of this.