Selecting chemical protective gloves

Where gloves need to be worn for chemical protections its important that they are suitable for the chemical and application concerned and will provide protection for an appropriate time period. Too often inappropriate gloves are worn and even if suitable ones are used, they tend to be used long after they are capable of providing protection.

If it is necessary to use gloves then the first consideration is “what is the chemical we’re protecting against“. Once we know this data should be obtained from glove manufacturers on the breakthrough time, and the permeation rate. The breakthrough time is the time it takes for the chemical to work its way through the glove, which is normally well before any physical degradation has occurred. This will allow the most suitable glove to be selected, as breakthrough times for different gloves for a particular chemical will vary considerably. It will also usually allow the useful life of the glove to be defined – and the replacement frequency.

Degradation data should also be obtained – this is about the physical deterioration of the glove – as this can sometimes occur before breakthrough. Usability considerations are important too. It’s no good specifying gloves that aren’t usable because they’re not compatible with the work or the user.

Each manufacturer should provide data for their own products .

A pdf version of Ansell’s latest chemical resistance guide is available from here. They also have their information on line.

One of the other main suppliers, Marigold, also have an online guide.

Other manufacturer’s should have similar information available. If not, you can’t use their gloves for chemical protection.

Plants aren't always good for you!

I spotted this article in the New Scientist.

I've often come across the view that using plants is a good way of dealing with pollutants in the indoor environment (see my previous post here). Although there is some merit in this, it isn't always true that plants are beneficial and the research findings described in the New Scientist article shows how plants can actually increase pollution.

All living organisms process, produce and emit chemicals. Sometimes these are beneficial and sometimes they are harmful. Just because something is "natural" doesn't mean that it is harmless. Botulinum toxin is a "natural" chemical - and its extremely toxic.

Handel exhibition suggests his poison was the lead in his wine

I spotted an interesting article in the Guardian last week, reporting on a theory that the composer Handel suffered from lead poisoning


Lead acetate used to be used to sweeten wine and this is suggested as the source of lead exposure for the composer. I've even heard it suggested that the fall of the Roman empire could be attributed to the same reason as they, apparently, were very fond of sweet wine and used to add lead acetate to it. There is a useful summary of the history of lead exposure here on the USEPA website

Lead and its compounds are highly toxic. The main concerns are its chronic effects (due to long term exposure) particularly as it is accumulates in the body, remaining there for a long time after exposure.

Its principle effects include

• anaemia,
  
• irritability, tiredness,
  
• effects on the nervous system leading to muscle weakness and, in extreme case, paralysis,
• kidney and liver damage
• gastrointestinal disturbances
• effects on IQ, particularly in children
• It is a teratogen, that is it can affect the unborn child when the mother is exposed, leading to spontaneous abortion, still birth or decreased birth weight,
  
• fertility problems in males
  

Inorganic lead compounds are are also classified as "probably carcinogenic to humans" by
the International Agency for Research on Cancer (IARC)

For a thorough summary of its effects see the document Information on lead from the UK Health Protection Agency

Exposure to lead in the developed world has fallen dramatically due to increased awareness, stringent legislation in the workplace (such as the Control of Lead at Work Regulations in the UK), environmental regulation and the reduction of lead in products to which the general public could be exposed. The banning of lead in petrol being a particularly important measure. Consequently cases of lead poisoning are relatively rare.

However, it is likely that lead exposure is increasing in the developing world as lead and its compounds are still widely used in manufacturing and with the rapid growth of industry in India, China and other countries it is likely that the exposure of workers and the general public will increase. Control measures to reduce the exposure of workers and minimise emissions to the environmental are likely to be considerably less stringent in newly developing countries than in the developed world. A report by the World Health Organisation discusses these issues and concludes that:

"Public health measures should continue to be directed to the reduction and prevention of exposure to lead by reducing the use of the metal and its compounds and by minimizing lead-containing emissions that result in human exposures."

Cupola furnace

I took this picture recently of a cupola furnace at a small foundry. Scrap metal and coal are loaded into the top of the furnace and the coal set alight to melt the scrap and produce molten metal which is used to manufacture castings.

As there is insufficient oxygen for complete combustion, carbon monoxide is generated. Hydrogen sulphide can also be produced due to the presence of sulphur in the coal. Both of these gases are highly toxic and have to be extracted to minimise the risk to the operators. Some of the gases dissolve in the molten metal and can gas off as it cools, so there can be some risk during the casting operation itself.

This is a good example of how hazardous substances can be generated during a process and which are often forgotten by inexperienced or untrained people carrying out health risk assessments.

A number of years ago I got involved with a company (NOT the one shown in the picture, I should point out) where a worker had been exposed to high concentrations of carbon monoxide when inspecting the furnace when a leak occurred. The company concerned had employed a safety consultant to carry out COSHH assessments for them. Unfortunately he based his assessments on the material data sheets for the substances bought by the company. There were no data sheets for carbon monoxide or hydrogen sulphide as they aren't bought in so there was no mention of two of the most serious risks in he foundry - i.e. potential exposure to the gases. There were other hazards he didn't consider too - metal fume created during melting and casting and exposure to respirable crystalline silica during "fettling" (the grinding of the finished castings to remove rough edges) - because again, these substances are created by the process and are not bought in.

Although most people seem to think that COSHH requires an assessment to be carried out for substances, this isn't actually the case - the assessment should actually cover the "risks created by work" where workers can be exposed to hazardous substances. Its best to start by considering the process and what workers and others can be exposed to - both bought in substances and any that can be generated by the process itself. Quite often it is the latter that present the most significant risks, as is the case with the cupola furnace and other foundry operatons. Listing the substances bought in and using the supplier's data sheets as the basis of the assessment is likely to lead to significant risks being missed.

Note: COSHH is an acronym for the British Control of Substances Hazardous to Health Regulations 2002