Tag Archives: Danish Environmental Protection Agency

Danish evaluate research on absorption of nanomaterials through the skin

An Oct. 3, 2013 news item on Azonano announces a report produced by the Danish Environmental Protection Agency on the state of research into dermal absorption of nanomaterials  (Note: A link has been removed),

 A new report published by the Danish Environmental Protection Agency (EPA) provides a comprehensive evaluation of the knowledge base regarding the dermal absorption of nanomaterials.

The report is the final output of the project “Dermal absorption of Nanomaterials”, which forms part of the “Better Control of Nano” initiative 2012 – 2015 conducted by the Danish EPA with the aim of further clarifying possible risks to consumers and the environment from nanomaterials.

The overall objectives of the project – which was led by the Institute of Occupational Medicine (IOM) working with COWI A/S – were to:  i) gather and evaluate the existing knowledge concerning the dermal absorption of nanomaterials, ii) assess the need to generate new knowledge, and iii) develop recommendations for the most suitable skin models, measurement methods and relevant candidate nanomaterials for future experimental testing.

The report: Dermal Absorption of Nanomaterials Part of the ”Better control of nano” initiative 2012 – 2015 Environmental Project No. 1504, 2013 gives a good description of skin and a good technical overview of the literature and the state of the research which, for the interested reader, could supply the basis for a better understanding of how to read research papers on this topic.  The report does not offer consumer information about nano sunscreens, etc.

Here’ are some of the conclusions from the Executive Summary,

One of the key challenges in assessing the literature on the physicochemical properties influencing dermal penetration/absorption of nanomaterials is that it is difficult to draw conclusions due to either: i) limitations in the reporting of physicochemical data, and/or, ii) the alteration of multiple experimental parameters in a non-systematic way. The issue of a lack of information on nanoparticle physicochemical properties is common, yet the most challenging aspect is the alteration of multiple experimental parameters whereby multiple characteristics such as shape, charge, coating, size can all be changed. This means that little meaningful comparison of results can be made within a single experimental study, let alone between studies.

Despite such challenges, some key conclusions can be drawn. [emphasis mine] Whilst there are many conflicting results, on balance the literature seems to suggest that absorption of particles in the nano-range through the skin is possible although occurs to a very low degree and that the level of penetration, depending on chemistry and experimental conditions, may be greater than for larger particles. The role of size is considered a critical component of dermal absorption but this in itself does not seem to guarantee absorption or lack of as other properties can also influence dermal absorption markedly. In addition, particle size is not necessarily a constant parameter as agglomeration of particles can occur over time and also in relation to experimental conditions (e.g. presence of surfactants within particle vehicle formulation). However, whilst this issue of agglomeration has been suggested as being important (as well as an important experimental variable), agglomeration state is often not reported within studies.

Two (Denmark & US) contrasting documents about nanomaterials and risk

The Danes released their NanoRiskCat (NRC) document in early December 2011 while the US National Research Council released its report on the US research strategy on environmental and health impact of engineered nanomaterials today, Jan. 25, 2012.

(BTW, There”s going to be an alphabet soup situation in this posting with two different NRCs [the catalogue] and the US National Research Council for starters. I’ll do my best to keep these entities distinct from each other.)

The documents represent an interesting contrast regarding approaches to nanomaterials and their risks. From the Jan. 25, 2012 Nanowerk Spotlight article about Denmark’s NanoRiskCat,

The project’s aim was to identify, categorize and rank the possible exposure and hazards associated with a nanomaterial in a product. NanoRiskCat is using a stepwise approach based on existing data on the conventional form of the chemical as well as the data that may exist on the nanoform. However, the tool still needs to be further validated and tested on a series of various nano products in order to adjust and optimize the concept and thereby to achieve a screening tool as informative and practical as possible.

Meanwhile, here’s the description of the US NRC’s latest report, from the Jan. 25, 2012 news item on Nanowerk,

Despite extensive investment in nanotechnology and increasing commercialization over the last decade, insufficient understanding remains about the environmental, health, and safety aspects of nanomaterials. Without a coordinated research plan to help guide efforts to manage and avoid potential risks, the future of safe and sustainable nanotechnology is uncertain, says a new report (“A Research Strategy for Environmental, Health, and Safety Aspects of Engineered Nanomaterials“)from the National Research Council. The report presents a strategic approach for developing research and a scientific infrastructure needed to address potential health and environmental risks of nanomaterials. Its effective implementation would require sufficient management and budgetary authority to direct research across federal agencies.

I find it interesting that the US government which has poured billions into its National Nanotechnology Initiative (NNI) is still trying to develop a research strategy for environmental and health impacts while the Danish (who have likely spent far less and, to be fair, likely have less bureaucracy) have created an assessment tool designed to evaluate the exposure to and hazards posed by nanomaterials found in consumer and industrial use.

One other interesting tidbit, both the Danish and the US Environmental Protection Agencies (EPAs) were instigators of their country’s respective documents. The Danish EPA was one of the three funders (the other two were the Danish Technical University and the National Research Centre for the Working Environment) for their NanoRiskCat. The US EPA was one of the sponsors  for the strategy report. The other sponsors include the The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council.

I have to admit I’m getting a little tired of strategy documents and I’m please to see an attempt to evaluate the situation. I’m not sure which version (alpha or beta) of the tool they’ve released but there’s definitely some tweaking to be done as the Danes themselves admit,

It is the view of the Danish EPA that the traffic light ranking [I’m assuming they assign a colour [red, amber, yellow] as a means of quickly identifying a risk level in their documentation of specific nanomaterials) of the health effects may be further modified to obtain a better ranking in the various categories. Thus titanium dioxide in sunscreen is ranked as red due to lung effects of titanium dioxide, because the tool in its present form does not sufficiently take account of which type of health effects that are most relevant for the most relevant exposure route of the product. In this case the inhalational exposure of titanium dioxide from a sun screen seems less relevant.

Yes, I agree that exposure to nanoscale titanium dioxide via inhalation is an unlikely when you’re using a nanosunscreen. Although given some folks I’ve known, it’s not entirely out of the question. (It’s been my experience that people will inhale anything if they think they can get high from it.)