Tag Archives: toxic

VOCs in the news

As part of our regular sweep of news items in the analytical sciences, we often come across instances where volatile organic compounds (VOCs) are the focus of attention. We thought it might be useful and interesting to bring these together in a regular round-up – so here’s the first!

VOCs used to profile bacteria

VOCs emitted by cultures of ten strains of the diarrhoea-causing bacterium Clostridium difficile have been profiled using a custom-built headspace–TOF MS setup. Paul Monk and colleagues at the University of Leicester, UK, identified 69 VOCs and used them to distinguish between the strains – methanol, p-cresol, dimethylamine, ethylene sulfide, dimethyl sulfide and methyl thioacetate were most of value. The authors say that their method “may have utility as a rapid means of identifying C. difficile infection”.

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The case for phthalates as endocrine disruptors strengthens

The case for phthalates being endocrine disruptors has been further bolstered by research carried out by John Meeker and Kelly Ferguson at the University of Michigan, Ann Arbor, USA. They used HPLC–MS–MS to assess urinary levels of 13 phthalate metabolites – primarily oxygenated and singly-hydrolysed derivatives of phthalate esters. Significant reductions of testosterone were found in both men and women of different ages. Notably, substantial increases in metabolites of bis(2-ethylhexyl) phthalate (dioctyl phthalate) in 6–12-year-old boys were associated with a 29% drop in testosterone.

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Apple tightens regulations on hazardous solvents

Benzene and n-hexane have been banned from use as cleaning agents and degreasers in the final assembly process at 22 of Apple’s iPhone and iPad production plants. Their new Regulated Substances Specification additionally stipulates that “All cleaning agents and degreasers used at final assembly process facilities for the manufacturing of Apple products shall be tested for benzene, n-hexane and chlorinated organic solvent content at a certified lab prior to use in production”, and that permitted levels in the breathing zone of workers must be <100 mg/m3 (28 ppm) for n-hexane, and <0.32 mg/m3 (0.1 ppm) for benzene.

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US National Academy of Sciences concludes that formaldehyde causes cancer

The long-running debate in the US over whether formaldehyde is carcinogenic took moved forward in August with the publication of a report by the US National Academy of Sciences (NAS), where they conclude that the answer is “yes it is”.

This follows their critical 2011 review of the US EPA’s draft assessment of formaldehyde. Although the EPA document said that the evidence is “sufficient to conclude a causal association” between formaldehyde exposure and a variety of cancers, the NAS review said that there were “recurring methodologic problems” in this study.

The new document from NAS is their own independent assessment of the literature through to November 2013. Here they conclude that there is “sufficient evidence of carcinogenicity” in humans for nasopharyngeal cancer, sinonasal cancer and myeloid leukemia, and “convincing relevant information” that formaldehyde induces mechanistic events associated with the development of cancer.

These and other aspects lead the committee to conclude that “formaldehyde should be listed in the RoC [Report on Carcinogens] as “known to be a human carcinogen”.”.

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Is carbon tetrachloride still being emitted despite global ban?

Studies carried out by a team led by Qing Liang at the NASA Goddard Space Flight Center, Maryland, USA, have suggested that the observed slow decline of the ozone-depleting carbon tetrachloride (tetrachloromethane) can only be explained if it is still being emitted (see also this press release). This stands in contrast to the near-zero emissions estimate based on production and feedstock usage, a result of the regulations initiated by the 1987 Montreal Protocol.
Liang’s research, which is based on computer modelling of the concentration gradient between the northern and southern hemispheres, estimates that current unknown emissions are still about 30% of pre-treaty peak emissions. He says “it is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CCl4 sources”.

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Up close and personal – The chemicals used in personal care products

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Recent research published in Occupational & Environmental Medicine carried out by Swedish scientists has again highlighted the exposure of hairdressers to potentially hazardous chemicals, this time of carcinogenic and sensitising toluidines in hair dyes and hair-waving (‘perming’) products.

This is just the latest in a long line of news stories about chemicals in personal care products – including methylisothiazolinone in suncream, triclosan in antibacterial products, and phthalates in nail polish,

The latest research, led by Gabriella Johansson at Skåne University Hospital in Lund, Sweden, has been picked up by a number of outlets, including Reuters, ChemicalWatch, SpectroscopyNOW, Medical Xpress, Nature World News and MedicalResearch.com. What the researchers found was that m-toluidine was present above the limit of detection in the blood of >97% of a cohort of hairdressers, personal dye users and controls (a total of 387 people), with the figure for  o-toluidine being ~50%. The chemicals were detected indirectly by GC–MS analysis of their adducts with haemoglobin, which is a good way of assessing average exposure because of haemoglobin’s relatively long lifetime.

This of course isn’t the first time that chemicals originating from hair dyes have raised alarm bells – p-phenylenediamine gained attention in late 2011 following a death from a suspected allergic reaction. The issue this time is that toluidines, unlike p-phenylenediamine, were banned from cosmetics in the EU in the late 1970s (as stipulated on page 18 of the original 1976 EU directive), so it is a surprise to find them in the blood at all.

Two facts uncovered in Johansson’s study seem to suggest that these haircare products are the source of the toluidines. Firstly, they found that o-toluidine concentrations increased with the number of hair-waving treatments, and that m-toluidine increased with the number of hair-dyeing treatments. Secondly, and more tellingly perhaps, they analysed a commerical (multi-component) hair-waving product and found both o-toluidine (up to 0.23 ng/g) and m-toluidine (0.15 ng/g).

However, the matter is not as clear-cut as it might seem, because, as the authors say “We evaluated the exposure … [for] hairdressers, consumers and controls, and found no overall significant difference.” Likewise, research last year led by Marie Thi Dao Tran at Copenhagen University Hospital found that “the prevalence and the severity of fragrance-related symptoms [of chemical intolerance] were similar in hairdressers and the general population”.

Such research points to a complex picture, with possibly multiple routes of exposure subject to factors not accounted for in the current study. Clearly, there is a need to devote more attention to where the compounds are coming from, as the authors themselves suggest: “A study measuring both exposure to aromatic amines and product analysis … would strengthen the conclusions about hairdressers’ exposure to carcinogenic aromatic amines, and is encouraged”.

Indeed, such analysis should really go hand-in-hand in this sort of study, and is essential in order to draw any meaningful conclusions from the work. Analysing all the haircare products used by several hundred people is not going to be a small task, but perhaps is illustrative of the amount of effort that needs to be made to link cause and effect in such a complex area.

The good news is that this sort of analysis – once a highly labour-intensive endeavour – is becoming increasingly quick and straightforward, because of advances in sample preparation and automation. Advanced analytical techniques like GC×GC–TOF MS are also playing their part, by making it possible to get reliable, quantitative information out of such highly complex samples – as we’ve illustrated ourselves in Application Note 522 for the case of allergens in cosmetics.

David Barden received his Ph.D. in Organic Chemistry from Cambridge University in 2004, and during his time as an editor at the RSC wrote news pieces for Chemistry World on various scientific topics. He is now Technical Copywriter at Markes International, where he draws on the expertise of his colleagues to explain how new thermal desorption and mass spectrometry technologies can be applied to analyse volatile organic compounds in a wide variety of situations.

 

How do we tackle ‘chemophobia’? The need for clear, simple information on the chemical consistuents of products

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Chemicals – what are they exactly? The starting point for any debate is your definition of the terms, and that’s why, when discussing public perceptions of chemicals, it’s easy to get side-tracked by what people mean when they say ‘chemical’.

For example, much has been made of the validity of describing products as ‘chemical-free’, a usage upheld by the UK’s Advertising Standards Authority and perhaps indicative of the ‘chemophobia’ phenomenon. However, speaking as a writer, how people interpret words is up to them. If someone understands ‘chemical’ to mean an industrially-synthesised one, then short of launching a nationwide awareness campaign, the rest of us just have to live with it – either by being prepared to be misunderstood, by explaining what it is we actually do mean, or by finding another word that does the job better.

So putting semantics to one side, and using the word in its broadest ‘everything-is-made-of-chemicals’ sense, what agreement is there on the main messages the scientific community ought to be putting out there? You could write a short book about this, and indeed the campaign group ‘Sense about Science’ have done just that, with their commendably level-headed guide Making Sense of Chemical Stories.

This document and other commentators converge on the following four points about ‘chemicals’, at least those present in consumer products:

Chemicals are chemicals, and their source is irrelevant to their properties, provided of course that they are pure. They could be extracted from a natural source, or synthesised industrially – it makes no difference (although you might of course care about who your money’s going to, or the environmental friendliness of the process used).

All chemicals would be harmful to you if you ate or breathed in enough of themit’s the dose that matters. Again, origin is unimportant, and there are examples of naturally occuring chemicals that are highly toxic, and man-made chemicals that are completely benign.

Chemicals underpin much of our modern way of living. Many chemicals are vital for for our civilisation to function – taking them away would send us back to the Stone Age. On the other hand, there are some, such as chemical agents and certain pesticides that, with the benefit of hindsight, mankind and the planet would have been better off without. Many of those are a legacy of a time when use of new chemicals was seen as inherent to ‘Progress’, resulting in their introduction to the environment with little thought given to any possible negative consequences.

These days, chemicals are pretty strictly regulated. Chemicals used in bulk to manufacture goods, foods, pharmaceuticals and cosmetics are well-characterised and their use is tightly controlled. However, our knowledge of many chemicals is incomplete, because we can never fully understand what will happen to them when they enter the environment, or account for every possible combination of exposure levels, organisms and uses (or misuses). Sometimes, allergic reactions or issues of bioaccumulation only become apparent over long timescales, but we can often make a good guess as to problem chemicals, and in such cases a precautionary approach is the wisest course (see my previous post on endocrine disruptors).

Is this too complicated for people to understand? Of course not, but why are public perceptions proving so slow to change? Part of it, undoubtedly, is that chemistry bloggers, as Mark Lorch of the University of Hull points out, are preaching to the converted. But even if they weren’t, would the message stick? Probably not, because understanding the above points doesn’t help me when I pick up a product on my weekly shop and look at the ingredient list. If I’m a concerned consumer, then I might ask questions like “what is this chemical?”, “what’s it doing in my food/lotion/medicine?”, and “should I be worried about it?”.

Now, unless you’re a food or formulation scientist, or have got the time and inclination to research ingredients on the internet, then you’re going to have to go without answers to these questions. This information deficiency is compounded by the skewed notion of risk that many people have from exposure to media stories about chemicals. The result is that the product chosen is the one perceived to be safer, namely ones marketed as ‘natural’, ‘chemical-free’, etc. Then at least you can rest easy with the knowledge that you did your best to protect yourself and your family from potential harm.

So what’s the solution? Perhaps this is somewhere where technology can help, by allowing access to ingredient lists for products, with clear and simple information on the purpose, source and health risks of each of the chemicals present. In most cases, this data already exists – all we need to do is to make it available to the consumer. It might be starry-eyed optimism on my part to assume that this might happen, but if we did, then wouldn’t it provide consumers with the power to deshroud the mystery of the chemicals in the products they buy, and enable them to make informed choices?

But before I get carried away here, what about all the other chemicals we expose ourselves to, through the air we breathe, the water we drink, and the everyday products we come into contact with? Should information on the chemical components of these materials be available too?

OK, so I didn’t say it was easy. But making available authoritative and easy-to-understand information on the chemicals we’re exposed to in at least some everyday products – as we currently do for potential allergens such as nuts, soya and gluten in foodstuffs – would be a pretty good first step in overcoming the scourge of ‘chemophobia’.

David Barden

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