Canary Girls

A couple of weeks ago I visited the latest exhibition showing at Manchester City Art Gallery – The Sensory War 1914-2014

This major group exhibition marking the Centenary of the First World War explores how artists have communicated the impact of military conflict on the body, mind, environment and human senses between 1914 and 2014.

Included in the exhibition were a number of pictures illustrating the role of women on the “Home Front”. Due to sending many hundreds of thousands of young men to the trenches in Europe there was a shortage of workers to man the production lines in the munitions factories. The solution was to recruit women.

This lithograph by Archibald Standish Hartrick, who worked as a war artist, shows a young woman filling shells with TNT explosive.


Women’s Work: On Munitions – Dangerous Work (Packing T.N.T.) c.1917

The “munitionettes” were referred to as the “Canary Girls” as many of them developed yellow skin due to their exposure to the chemicals they were handling.

TNT (2,4,6-Trinitrotoluene) as well as being highly explosive presents a number of serious health effects such as anemia (reduced number of red blood cells and reduced hemoglobin and hematocrit), liver function abnormalities, respiratory complications, and possibly aplastic anaemia (ASTDR).

TNT can interact with haemoglobin to form methaemoglobin, reducing the capacity of the blood to carry oxygen and causing cyanosis – so it’s a chemical asphyxiant. It can also damage the liver, leading to jaundice and the yellow colour of the skin.

Exposure can occur by inhalation of dust and also by skin absorption – both potentially significant for the worker portrayed in the picture. The control measures leave a lot to be desired with what appears to be direct hand contact and only the use of a primitive mask to control inhalation exposure with no evidence of any engineering controls.

For King and Country (1916) by Edward F Skinner Source: Imperial War Museum – used under the terms of the IWM Non Commercial Licence.

Conditions in munitions factories have improved considerably since the First World War and stringent control measures are implemented when TNT is handled. A UK Workplace Exposure Limit of 0.5  mg/m3 (8 hour time weighted average) has been established for 2,4,6-Trinitrotoluene.

One of my colleagues undertook some sampling in a factory where 2,4,6-Trinitrotoluene was being handled recently. I’m glad to say that it was being controlled effectively and the airborne concentration was below the level of detection of the method.


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!

Android Apps for Occupational Hygienists


In my last post I listed some free to download apps for the iPhone and iPad that can be useful for occupational hygienists. Here are some free apps that can be downloaded on Android phones.



Also available for the iPhone/iPad, Windows and online. Designed to assist first responders in hazardous material incidents this app has some very useful information on the chemical and physical characteristics and human health data for a large number of chemicals.


Dangerous Goods Manual


Another resource providing key information on hazardous substances

Cargo Decoder


Another free resource with information on hazardous substances, primarily aimed at first responders.



IH Dig


Also available for the iPhone / iPad, IH DIG (Industrial Hygiene Data Interpretation Game) is a game which allows occupational hygienists to test their skills at anticipating exposure data. A useful educational tools, and not just for those new to the field!


If anyone has other recommendations to add to the above, why not post a comment.

IPAD Apps for Occupational Hygienists

In a previous post I looked at some websites that I use regularly to find information on chemical hazards. I suspect that many occupational hygienists have an Android phone, iPhone, iPad or Android tablet that they carry around with them. Although these can be used to access the websites I mentioned in my post, there are also a number of useful apps that can downloaded from iTunes or Android Play (what used to be called the Android Marketplace).

These are some iPad iPhone that I’ve found useful. (I’ll follow up with a post on apps for Android phones)

IH Calculator Lite


This one “does what it says on the tin”. Its described as

“an interactive calculator that performs occupational health and safety calculations to aid industrial hygienists.”

It allows the user to carry out various key calculations on noise, heat stress and ventilation. The formulae are American and so use Imperial units, which can be a particular problem with ventilation calculations. But the app does include a module that converts from Imperial to SI units.

iPhone Screenshot 1




A mobile version of the US National Library of Medicine’s WISER (Wireless Information System for Emergency Responders). Although designed to assist first responders in hazardous material incidents this app has some very useful information on the chemical and physical characteristics and human health data for a large number of chemicals.

iPhone Screenshot 1




A German database which includes occupational exposure limits for over 15000 hazardous substances from various EU member states, Canada (Québec), Japan, Switzerland, and the United States as of January 2011.

iPhone Screenshot 1


Hazmat Load


This app the uses "Segregation for Hazardous Materials" and "Class 1 Explosives Compatibility" Tables to allow the user to determine whether materials need to be segregated during transportation.

iPhone Screenshot 1


Chem safety


An app giving access to the International Chemical Safety Cards [ICSC] which summarize essential health and safety information on chemicals for their use at the "shop floor" level by workers and employers.

iPhone Screenshot 2


HazRef Lite


A portable database of over 2,000 hazardous materials as identified by the US Department of Transportation. Each material is identified by: proper shipping name, United Nation’s designated number, DOT hazard class and placard and more.

iPhone Screenshot 2


IH DIG for iPad


IH DIG (Industrial Hygiene Data Interpretation Game) is a game which allows occupational hygienists to test their skills at anticipating exposure data. A useful educational tools, and not just for those new to the field!


If anyone has other recommendations to add to the above, why not post a comment.

Risk Management Measures in the real world


At the end of October, I travelled over to Helsinki for a few days. I’d been invited to deliver a short course on “Risk management measures in a REACH context”  to personnel working for the European Chemicals Agency* (ECHA) who are responsible for evaluating the dossiers chemical manufacturers have to submit under the European REACH Regulation. Over 30 people attended the course, a much bigger number than I’d normally prefer. However, they were a really nice group of people who were keen to listen and contribute to the discussion making it an enjoyable experience for me, and, I hope, for the attendees. It was good to have the opportunity to put forward my perspective on how effective risks from hazardous substances are controlled in practice in the “real world of industry.

The principle objective of REACH is to protect human health and environment from chemical hazards, ensuring that risks from the use of chemicals are properly controlled. To achieve this, manufacturers have to undertake risk assessments for all “exposure scenarios” where their products are used and produce “extended safety data sheets” for substances, which must include appropriate “risk management measures”. We’re now starting to see these new style data sheets coming through to users.

During the training session, we looked at how exposures to chemicals vary and the practicalities of obtaining adequate data for the risk assessment process. However, the main discussion centred on the realities of how “risk management measures” are implemented in industry, based on my experiences helping companies to control the risks from using hazardous substances.

I think that there is a widespread impression that controls are much more effective than they are in practice. There are lots of reasons for this, which I’ve discussed in some previous posts. Problems can occur during all the key steps involved in the design and implementation of controls – see my Slideshare presentation and this post for some examples.

It’s a particular problem with local exhaust ventilation systems. In my experience they are rarely well designed and, in practice,  their influence on exposure is considerably less than the users (and designers/suppliers) believe. The “lower tier” exposure models commonly used to prepare the REACH risk assessments can assume that LEV is up to 90% effective. The system would have to be well designed and properly used and maintained for this to be the case and I think that it is rare for it to be achieved in practice. Consequently, exposure modelling with lower tier models can considerably overestimate the reduction in exposure achieved by LEV.

Manufacturers and importers of chemicals need to make judgements about the effectiveness of controls when carrying out their risk assessments and also when deciding on what risk management measures are needed. The danger of overestimating how good they are could compromise their risk assessments and result in risk management measures being specified that won’t adequately control exposure. It’s important, then, to have a realistic appreciation of the “real world” effectiveness of common controls.

Those extended data sheets I’ve seen so far seem to specify realistic controls for the exposure scenarios. However, they are phrased in very general terms. Again this is likely to be a particular problem with LEV. For many industrial organisers “LEV” means a captor hood – often the flexible “swinging arm” type. As I’ve discussed in a previous post, these are largely ineffective at controlling contaminants. But in many cases if a company follows a general recommendation to install LEV, this is what they’ll buy.  I think that if REACH is really to achieve it’s objective of improving control, then we need to ensure that the advice on risk management measures is as specific as practicable. So with LEV enough details needs to be provided to make sure that the design of the extraction hood is appropriate.

Milling polyurethane blocks at semi automated machine
Inappropriate application of a captor hood

Another problem I’ve noticed with the new style safety data sheets I’ve seen is that where personal protective equipment is recommended the advise is too general. For example, recommending “wear suitable gloves”. This really isn’t any improvement on the older style sheets. Downstream users need more specific advice on what type of gloves are needed, particularly what they should be made of. The reality is that most users don’t have the expertise to select “suitable gloves” and in most cases the gloves used are made of an inappropriate material and are not used and managed properly.  This point is also relevant to other types of personal protective equipment. Again, I’d like to see more specific details provided.


For me a good model for user friendly control advice is the COSHH Essentials control sheets. These provide good, concise advice on control for common processes on a maximum of 2 sides of A4. Where LEV is recommended specific details on the hood design, including an outline diagram, is provided. These sheets aren’t perfect – their advice on personal protection is too vague, for example – but I think that overall they strike the right balance between brevity and the usefulness of the information.

A lot of work has to go into carrying out the risk assessments. It’s important that the output – i.e. the information on risk management measures – should be detailed enough to ensure that controls are properly designed and implemented. Unless this happens there’s a real danger that all the effort will be in vain and an opportunity to substantially improve control of hazardous substances at work will have been missed.

*ECHA’s role is to manage and coordinate the registration, evaluation, authorisation and restriction processes and to ensure consistency in the management of chemicals across the European Union.

COSHH Assessments – 7 key questions


In my last post I discussed the main problems that I often encounter with how COSHH assessments are carried out in practice. These were

  • concentrating on the hazards rather than the risks
  • neglecting to include process generated substances
  • concentrating on inhalation exposures and neglecting other routes
  • lack of emphasis on controls
  • failure to consider measures needed to ensure continued effectiveness of controls

To be “suitable and sufficient” a COSHH assessment needs to address the risks associated with the use of hazardous substances and decide on what measures are needed to reduce them to an acceptable level. The best way to achieve this is to base the assessment on the work. COSHH assessments should be focused on the process or task rather than the substance.

Guidance on risk assessments typically outlines a number of key steps as illustrated in the following flow chart




Although this provides a good overview of the process it is a little vague. In particular, it doesn’t really set out what is involved in the crucial third step – evaluating significant risks.

Some time ago, I sat down and tried to work out exactly what I do when I carry out a COSHH assessment. I concluded that I ask myself a series of questions:

  1. What substances are workers (and others) exposed to?
  2. What harm can these substances cause?
  3. Is exposure significant?
  4. What is currently being done to control exposure?
  5. Is that good enough?
  6. What needs to be done to improve control?
  7. What else needs to be done to ensure that adequate control is maintained? (e.g. testing controls, air monitoring, health surveillance, training etc.)

Let’s have a look at these in a little more detail

1. What substances are workers (and others) exposed to?

  • Starting with the task or process work out what substances are present – including both those substances bought in and those generated by the process (the latter often present the most significant risks).
  • Consider who could be exposed and how – i.e. by what routes (inhalation, skin, ingestion, injection)

2. What harm can these substances cause?

  • For substances bought it should be possible to determine the hazards they can present to health by looking at the label on their containers and the safety data sheet that suppliers must provide.
  • Information on process generated substances might be more difficult to locate, but the Health and Safety Executive publications and their website are often a good place to start.

For many people this is the end of the assessment, but if you stop here you have only identified hazards and haven’t addressed the risks. You need to continue to consider the other questions.

3. Is exposure significant?

This is probably the most difficult question to answer! Bear in mind that with hazardous substances the risk can be represented by the following equation :-


So the key is to try and quantify or estimate the degree of exposure. There are various ways this can be achieved, for example

  • personal air sampling
  • use of direct reading instruments
  • semi-quantitative measurements (e.g. direct reading dust monitors)
  • visualisation techniques (e.g. dust lamp or smoke tubes)
  • observations


The methods used will depend on circumstances. Sometimes observation is enough where it is obvious that improved controls are needed.


Whatever methods are used, a judgement has to be made on whether exposure is “significant” or not. Essentially you need to ask yourself “does something need to be done to reduce exposure?”. If the answer is “yes” then exposure is significant. (This is something I’ll return to in a future post)

4. What is currently being done to control exposure?

This question may be combined with the previous one. In most cases a COSHH assessment will be undertaken for an existing process where there are likely to be controls in place. You’ll need to identify what they are.

With a new process, the initial COSHH assessment should be carried out before the process starts. In that case you’ll need to identify what control options are available.

5. Is that good enough?

This may be asked in conjunction with questions 3 and 4. Once it’s been established what controls are available a judgement needs to be made on whether they are reducing exposure to a low enough level.

6. What needs to be done to improve control?

If existing controls aren’t good enough then, clearly, improvements will need to be made. A COSHH assessment should identify what measures are needed to control exposure.

Even where exposure is below exposure limits if there are ways of improving control they should be considered. For example, if personal protection is being used, even if it is adequate to reduce exposure below exposure limits, an attempt should be made to identify alternative controls.

Also if workers are exposed to carcinogens, mutagens or asthmagens, COSHH requires that exposure should be reduced to the lowest level reasonably practicable below any relevant limit. So in such cases it is particularly important to try to identify any additional controls.

7. What else needs to be done to ensure that adequate control is maintained?

This is probably the most neglected aspect of COSHH assessments even though the Regulations are quite explicit in requiring the assessment to consider what measures are needed to ensure compliance with all the regulations.

There are many examples in industry where expensive control measures are installed only for them to remain unused, used infrequently or used incorrectly thereby rendering them ineffective. To overcome these problems, effective management measures need to be put into place. COSHH Regulations 8 to 12 are about the things employers can and should do to ensure the controls they implement continue to work effectively. So once appropriate controls have been identified, the assessor needs to ask:

  • what needs to be done to ensure that the controls are used properly
  • what maintenance and testing is needed to ensure that engineering controls and personal protective equipment continue to operate effectively and what auditing should be carried out to ensure that the procedures and safe working methods are followed
  • is exposure monitoring and health surveillance needed as additional checks that the controls are effective
  • what information, instruction and training is required to ensure workers know why the controls are needed, how to use them correctly, procedures for reporting faults etc.