Simple Answer; “Scare you so much that you will never do any practical work with students again”. (But you could watch paint dry!)

I delivered a talk on this at the BCCE2016 at North Colorado State University in August 2016. Many people from the States commented on how different our UK safety culture is to that States. I have found it to be different to many places in Europe as well. To those of you in the UK, I must admit that CLEAPSS and SSERC (in Scotland) are “one-off” organisations which contribute so much to the science education in the country. The UK teachers and technicians should also thank the sensible approach of our Health and Safety Executive and how our Health& safety at Work Act 1974 works. (The UK consistently has one of the lowest rates of fatal injury across the EU. In 2012 the standardised rate was 0.58 per 100, 000 workers, which compares favourably with other large economies such as France (2.64 per 100, 000 workers), Germany (0.9 per 100, 00 0 workers), Italy (1.29 per 100, 000 workers) and Spain (1.99 per 100, 000 workers) (Eurostat, ESAW, 2012). The number in the USA is 3.3 per 100,000 workers (Bureau of Lobor Statistics)).As far as I know, although there have been some serious injuries in science education, there have been no deaths in school science lessons. However, there have been in school sporting and outward bound events but these activities are never banned.

Whenever a serious incident takes place in a school chemistry laboratory or classroom, fire and safety officers often pontificate on the incident by quoting the Safety Data Sheet (SDS). However, how many of you have read such documents in full? In UK schools we have perhaps 200 to 400 chemicals on the shelves. Have you read the SDSs for each chemical? The picture below show one educational establishment asking their students to read 7 SDS sheets before they start, ie a total of around 77 pages!

Did you even know there was such a thing

as a SDS or do you just “always read the label”. In the UK, we have many very experienced school laboratory technicians who do have access to the SDSs and to a large extent, protect the teacher and so I suspect there are some teachers who do not know that they exist. In the EU and the USA, we have to store the MSDS sheets electronically or in a filing cabinet. I suspect once in the storage area they are never read.

SDS can be seen to be silly

This statement may seem impudent in the extreme. After all, many really well-qualified chemists and toxicologists in the United Nations, Occupational Safety & Health Administration (OSHA), European Chemical Agency (EChA), Health and Safety Executive(HSE) and countless other organisations in all the developed countries in the world have spent many hours of serious debate and research on implementing the United Nation’s Global Harmonised System. The aim is to ensure that the same information is available on chemicals no matter which continent you are in.

Yet I can show the section on sodium chloride and sterile water to any experienced chemistry teacher and the response will be “This is silly”.

You can imagine the coffee-time discussion amongst teachers and lecturers of chemistry discussing and ultimately dismissing these documents in no uncertain terms as “unbelievable”. The issue now is that the MSDS loses its credibility amongst the experienced chemistry teachers; that can be dangerous and a complete disregard of the use of SDS is illegal.

It is obvious that a computer is at work but with companies supplying thousands of chemicals mostly to Industry, Hospitals and Universities and only a small percentage to Schools and Colleges, I hope you can see the suppliers’ problem. The format of these SDS documents are enshrined in the advice from the United Nations.

Sometimes the suppliers are not correct

UK schools have informed CLEAPSS of chemicals with any hazards which seemed to be different from those they had previously received. I remember the first one. Vaseline (usually no hazard classification) was ordered by a school from a supplier but it came with a carcinogen warning. The school contacted the educational supplier but the reply was “It is the new laws”. It was only when the school contacted CLEAPSS, worried that they had been using a substance which was carcinogenic, for tens of years with students (and on themselves!), that we managed to get the supplier to go to their supplier to confirm that her supplier did not classify substance as carcinogenic. Now, there was a reason for the hazard warning because if any supplier was taking the information from the European Chemical Agency (ECHA) website, Petrolactum or Vaseline did carry a carcinogen warning but with this comment: “The classification as a carcinogen need not apply if the full refining history is known and it can be shown that the substance from which it is produced is not a carcinogen”. This comment is easily missed. The educational suppliers have made other mistakes and poor interpretations of the law. They are learning to cope with the new legislation as it is acknowledged to be very complicated. What teachers might not realise is that a SDS is generated when the chemical enters or is manufactured in the country. The information has to be passed down to the next outfit in the supply chain and so on until your school buys the chemical. In this game of “whispers” mistakes are bound to happen.

A sole teacher in a small school was frightened to open a bottle of magnesium powder (required by an exam board for an assessed practical exam) because on the label it said H250: Catches fire spontaneously if exposed to air. Again, there had to be careful reading of the documentation because a Note said that “This substance may be marketed in a form which does not have the physical hazards as indicated by the classification”.

The UK is fortunate to have a HSE Helpline, The Environment Health & Safety Committee at the Royal Society of Chemistry and the Chemical Hazards Communication Group (industrial) for advice and help. The Health and Safety Executive (HSE) and the RSC are adamant in their support of chemistry practical work in schools. It is necessary to work with the system and not against it.

SDS can be emotive

What does the word “fatal” conjure up in your mind? “There has been a fatal accident” on the news suggests a person has immediately died but in “GHS speak” it means very toxic. The SDS sheet for sebacoyl chloride, a chemical we use in the UK in schools to do the “nylon rope experiment” has to say the substance is fatal on contact with the skin and CLEAPSS received a number of calls on the word “fatal” and the question “is it banned?” In fact, the degree of hazard had not changed from before GHS, but then it was written as “very toxic in contact with the skin” and nobody made a comment about that. In fact I actually poured 2 to 3 ml of this solution on my hand, washed it off and I am still here.

The hazard ratings for chemicals are not given “on the nod” but need criteria as provided in guidance in a document called the Purple Book. It does involve animal testing but one is assured this is kept to a minimum. Because of the complexity of the area, suppliers do get it wrong and if it seems wrong to you, your professional body may be the first point of call as they may have a safety section. Communicating this information to non-scientists or even scientists of a different persuasion can be difficult.

The SDS does not take into account dilution

(“The dose makes the poison” – Paracelsus)

The school buys sodium hydroxide pellets. The teacher/technician makes a solution and dilutes the solution to 0.1M. The MSDS sheet is only relevant to the person making the solution as it makes no comment about dilution. Even if you buy a dilute solution, the true hazard classification of the solution can be hidden in the wording of the SDS. I have seen SDS sheets for 0.2M sodium hydroxide which quote the hazards of solid sodium hydroxide with no mention of the reduction of hazard caused by dilution.

The teacher is left floundering as to the classification of any diluted solution. In Europe 0.2M sodium hydroxide classified as Signal Word: Warning with H319: Causes serious eye irritation. The figure below from the reverse of a CLEAPSS Hazcard (available to all schools in the UK) shows how the dilution affects the hazard of the sodium hydroxide on dilution.



These cut off concentrations differ for every substance because it is calculated by percentage by mass of substance or element present. So the dividing lines for dilution effects are different for potassium and sodium hydroxide solutions.CLEAPSS obtain these values in the European Chemical Agency (ECHA).

CLEAPSS recommends, after applying our safety regulations on risk assessment, that using sodium hydroxide solution at 0.4M (Warning) compared to 0.5M (Danger) allows the user to wear the more comfortable safety spectacles rather than the uncomfortable goggles, which are prone to misting up.

Naturally, these reductions in hazard through dilution apply to toxic chemicals. Copper(II) sulfate(VI) solutions lose the Harmful if swallowed warning at concentrations less than 1M and solutions at concentrations less than 0.6M have no hazard warning. This does not mean that teachers have a free hand to do what they like with 0.5M copper(II) sulfate(VI) solution; good laboratory etiquette is important at all times.

The changes to hazard classification with dilution are very important when it comes to carrying out risk assessments.

The SDS does not take into account exposure time

I hope you now realise that the SDS, although containing a lot of useful information, is more relevant to activities in industry where people are working with chemicals often 8-10 hours a day for a year. Obviously, in those conditions the degree of exposure is considerably higher. The word “exposure” is an unfortunate term because in law and the tabloid press, it can mean all sorts of unsavoury habits of certain individuals with weird minds. In the world of toxicology, looking at a chemical such as lead nitrate is not going to cause you a problem. Exposure means intake into the body by 3 possible routes, ie, inhalation, ingestion and through the skin (the dermal and ocular route). Some chemicals do have an immediate effect (acute); sulfur dioxide and chlorine can cause breathing difficulties but we, as teachers, should know this and apply appropriate control measures to minimise exposure. I use a microscale method of electrolysing copper chloride solution which produces less than 6 cm³ of chlorine gas in a Petri dish. If I am reacting chlorine in a gas jar with sodium or iron, I would use a fume cupboard (fumehood), which vents the gas to the atmosphere or absorbs it into a filter.

The SDS does not take into account volume and amount

Teachers may now regard with some justification that the information in relation to toxicity, both chronic and acute SDS is more relevant to industry where employees may be in contact with large amounts of material possibly as a dust or aerosol for the working day and throughout the year. This regular contact can seriously affect health.

The SDS sheet does not take into account the tiny amounts of material used by teachers and students. However, we have already seen that the information on flammability, acute toxicity, corrosion and irritation to the eyes and skin is important. Please remember that corrosion is not about rusting but the destruction of body cells.

Using smaller amounts is even more important with flammable materials. Both in the USA and UK, people have been badly burned with flammable liquids such as methanol catching fire and there are large outcries to ban the chemicals used. In the UK a boy was badly burned on the chest (made worse with a rubber lined T-shirt underneath), leaning over a tea-light. Should we ban tea-lights, candles in restaurants etc? It is constant vigilance and training on the part of the teacher, assistant and technician which matter and, more importantly, a realisation that the school-science staff need continual professional development, training etc. In the UK, senior management have a duty of care to monitor that science teachers are adhering to the rules. I don’t think they or anyone in Industry likes this, it but it is enshrined in our Health and Safety Law; it would be easier to simply blame and sack the teacher for an incident.

Teachers love teaching and they love to enthuse the students in a wonderful subject and they can easily push the boundaries too far by making a demonstration bigger. They see lecturers in lecture halls burst large balloons of hydrogen and oxygen, do “Liebig’s barking dog”, ignite large soap bubbles of methane or hydrogen (NOT LPG), in the air or their hands, breathe in helium and sulfur hexafluoride to affect the pitch of their voices. It all looks very easy but these lecturers rehearse and rehearse these demonstrations. (I call them edutainers!) The teacher cannot simply take these demonstrations into the classroom without a lot of research, training and practice. Balloons of hydrogen and oxygen are too loud for a small room and can cause deafness, Liebig’s barking dog can explode (as it did when he did it), burning gases on the hands can cause serious burns especially if LPG is used and inhaling gases is just bad practice in a school context as it can lead to bad habits by students.

The SDS does not take into account the products of a chemical reaction

Seawater is about a 0.05M solution of sodium chloride. It is not classified as hazardous although with large exposure it can kill by ingestion of large volumes, it can be absorbed through the skin (ocean swimmers grease themselves) and breathing it in is pretty dangerous too! In the laboratory, I can put 2 carbon electrodes in sea water, connected to a low voltage supply, and generate chlorine, a highly toxic gas which can upset students with asthma. But there is no SDS for chlorine as the school does not buy the gas.

0.05 M sodium thiosulfate and 1M hydrochloric acid are not classified as hazardous but mix them together and sulfur dioxide is formed, a toxic gas. You do not have a SDS for sulfur dioxide because you do not buy it. I cite both of these experiments because they have both caused students to be taken to hospital for checks on breathing and the inevitable call from safety officers and school managers as to why we are subjecting students to distress. These were activities set by examination boards for assessment. In both cases the teachers involved were not chemists by training and the lessons got out of hand. The exam had been set by experienced chemistry specialists who knew (and probably thought all teachers knew) about the hazards of the products. The other essential part of this experiment is to pour the products of the reaction into a stop-bath of sodium carbonate solution which stops the reaction and neutralises the sulfur dioxide.

It has taken 20 years for a reduced scale method developed by CLEAPSS to be finally cited by our exam boards to be an accepted method of carrying out the reaction.

They are not risk assessments

Many articles on chemistry experiments cite hazards. The teacher should be more concerned about risk, the chances of an incident taking place and the potential severity/extent of harm that may be caused. Teachers of science need to demonstrate to senior management that they have reduced the possibility of an incident taking place and to ensure the use of the most comfortable personal protective equipment as the last resort. They can show this by including the method and relevant control measures in their schemes of work (SOW). As well as columns in SOW to please educational inspectors (eg learning objectives), there needs to be a column which shows that the teacher understands the possible risks from an activity and has taken steps (control measures) to reduce them. Both teachers and senior management should be aware that risk cannot be totally eliminated. The important factor is not to make a recorded risk assessment a huge multi-page document which will end up stored in a filing cabinet and never read (teachers do not have the time), but a few simple sentences to remind yourself (you might only do this activity once a year) and to remind your other colleagues who may take a lessons in chemistry. Lowering the concentration of a solution to a level which still illustrates what you are trying to show and has the smaller number of hazard statements is one way of showing that you applying risk assessments (hazard analysis). Teachers can add 0.4M sodium hydroxide solution to 0.1M copper(II) sulfate(VI) solution and still obtain a beautiful precipitate, instead of using 1M solutions which are far more hazardous for students to use. I can reduce the risks further by placing drops of these reagents on a plastic sheet.

If a teacher makes an improvement in safety, the SOW can be easily altered.

The teachers’ risk assessment needs to look at how the chemicals are presented to students to improve classroom management

It is important to focus on the relevant risks. In the last few years, boron compounds, used in producing green flames with methanol, have been given a hazard waning that they can cause harm to the unborn child. I have had teachers on the phone worried sick that they have used boric acid when they themselves or the students are of child-bearing age. The fact that methanol is very flammable, as highlighted in a recent report by the USA Chemical Safety Bureau into serious fires in schools, is never considered as the main risk. Many chemical text highlight the toxicity rather than the flammability. Yes it can be stolen, sold as cheap vodka and drink by addicts but this is a low risk in a school compared to its flammability. Teachers in the UK can contact CLEAPSS or SSERC in the UK for a safe version of rainbow flames but our risk assessment uses ethanol (less toxic) and around 6 ml per beaker (reduce volume).

it is also interesting that if there is a chemistry incident, there is move to ban the use and procedure. If a student is injured playing rugby, hockey, American Football, cricket, baseball, climbing rocks, skiing etc, is there an outcry to ban these activities. Doctors who speak up are criticised as scare-mongering, stopping fun etc. If I say in some in countries that you can melt 0.5g of lead or demonstrate the remarkable nature of mercury in the open lab some people raise their hands in horror. But I have done a risk assessment; convincing non-chemists is very difficult though.

You need training in how to use them

The teacher may be involved with over 400 chemicals in the year used in small amounts, for a few minutes and perhaps once a year. The industrial worker may be involved with 2 chemicals used in tonnes and litres (gallons) for the whole working year. The chemistry teacher might carry out 400 single operations with hazardous chemicals in the year. The industrial worker might carry out only 2 hazardous operations but they are repeated daily and all through the year. Both situations have their dangers in complacency.

It often comes as a surprise to both teachers and educational managers that risk assessment or hazard analysis is important for any work with hazardous chemicals with the MAIN findings recorded.

The problem with safety training is that it can, in the hands of some, be a frightening list of ‘don’t do this’ and ‘don’t do that’. It can sometimes be over-emotive and worst of all, patronising. Safety training works best when it shows how procedures should be carried out and then by monitoring in a sensitive manner.

A local Health and Safety Officer from the Armed Forces, Chief Fire Brigade officer, an expert in Heavy Lifting and grave digging and, dare I say it, large-scale chemistry engineering or a recent graduate in science is not always the right person to deliver this training to teachers of chemistry.

So back to that experiment on hydrolysis of tert butyl chloride.The photo below shows a slide describing the volumes used in the experiment. Does really reading the SDS for these chemicals help the student?