n-hexane

There was an interesting article in the Guardian a few days ago about the use of n-hexane in a factory in China. The company in question, which produces touch screens fro companies including Nokia, was using the solvent to clean the screens.

N-hexane is one of the organic compounds we study on BOHS Module course M101 ”Effects of hazardous substances”. As an alkane, we wouldn’t expect it to be particularly toxic. Alkanes generally are mild irritants and narcotics (substances that cause depression of the nervous system leading to effects similar to drunkenness). N-hexane is different in that it has been found to have another more serious chronic (i.e. long term) effect. Exposure to the compound can lead to peripheral neuritis – damage to the peripheral nervous system – causing symptoms such as loss of sensation in the fingers. There’s a good summary on the effects of n-hexane here.

The effects on the peripheral nervous systems are not due to the substance itself, but one of it’s metabolites - hexane-2,5-dione. It’s an example where the bitransformation of a substance in the body produces a more toxic compound.
The harmful effects are well known, and in the UK, Europe and the USA companies with a commitment to the health and safety of their workers would avoid using n-hexane wherever possible. It seems that the Chinese company actually used n-hexane as a substitute for the less toxic ethanol. According to the Guardian report about 49 workers were affected. The problem could have been avoided if a serious attitude was taken to health and safety and the principles of occupational hygiene were applied.

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.

New asbestos guidance

The HSE has jst launched it's new asbestos survey guide.

It can be ordered, or, even better, download for free from http://tiny.cc/6XNcH

"This heavily illustrated publication replaces and expands on MDHS100, surveying, sampling and assessment of asbestos-containing materials. It is aimed at people carrying out asbestos surveys and people with specific responsibilities for managing asbestos in non-domestic premises under the Control of Asbestos Regulations 2006. The book covers competence and quality assurance and surveys, including: survey planning, carrying out surveys, the survey report and the dutyholder's use of the survey information. It includes extensive appendices and references and it complements and supports other guidance on managing asbestos."