Nanoparticles in cosmetics and skincare

Zinc Oxide used in sunscreen is very obviously white in it's microparticle form (left) but almost undetectable in its nanoparticle form (right)

Zinc Oxide in sunscreen is very obviously white in it’s microparticle form (left) but almost undetectable in its nanoparticle form (right)

I recently bought a bottle of sunscreen in New Zealand and was surprised to see it specifically state on the back of its packaging that that it contained “micro” not “nano” ingredients.
This was the first anti-nano labeling of skincare that I had seen here and very different to the pro-nano labeling of cosmetics I had recently witnessed in Asia.

The new Environmental Protection Agency rules on labeling nanopartices in cosmetics are due to come in to effect next year and will be making us all a little bit more aware about the use of nanoparticles in some of the products we buy.

In the first of a regular series about nanotechnology I chat with Mark Sainsbury on his Radio Live Sunday morning show about where we might find nanotechnology in skincare products and what they are commonly used for.


Nanomaterials have been used to try and improve the performance of a wide range of skin products, from moisturisers and anti-ageing creams to hair care and razor blades. Many of the big cosmetics manufacturers have at least some nano products in their range but most of us are unaware of this as they do not have to be disclosed. As there is still some controversy over the safety of nanomaterials and its poor regulation worldwide, the EPA has created a rule which will enable more transparency of which cosmetics actually contain nanoparticles. As of July 15th 2015, the presence of nanomaterials (classed as a natural or deliberately engineering insoluble particles ranging in size from 1 to 100 nanometers) used in cosmetics must be labeled with the word ‘nano’ in brackets next to the ingredient.

Cosmetic bought in Asia which specifically labeled nanoplatinum as an ingredient

Cosmetic I bought in Asia which specifically labeled nanoplatinum as an ingredient

When I was in Hong Kong recently, I noticed that many of the expensive cosmetics on sale specifically marketed and directed consumers to the nanoparticles labeled in their ingredients. Asia seems to have a trend of marketing nanotechnology as a positive advanced technology with a clear explanation as to how nano ingredients would help to improve the product.  This seems to be a distinct contrast against the sunscreen that I recently bought in New Zealand which specifically stated that it contained “miconised not nano zinc oxide” on the back of the product which seemed to be marketing itself as a more natural product.

This sunscreen bought in New Zealand states micro not nano ingredients

This sunscreen bought in New Zealand states micro not nano ingredients


Zinc oxide is added to sunscreen because of its ability to absorb or scatter the sun’s ultraviolet radiation and prevent sunburn, the size of the particle has been reduced over recent years from micro to nano which has led to suncreens that visually blend better into the skin.  There is increasing research into the safety of nanoparticles as well as how the body deals with these foreign particles if they do penetrate through the skin.  A recent study published in the journal ACS Nano exposed white blood cells (macrophages) to zinc oxide nanoparticles which are typically found in sunscreens.  They counted how many of the particles were absorbed by the cell and found that within 24 hours the cells were able to break down 50-60% of the nanoparticles absorbed.  Although this was a lab cell study and not an in-vivo human study, it predicted that the body’s immune system would most likely break down nanoparticles before they could enter the bloodstream.  Although currently there is no specific regulation about how to test for the toxicology of nanoparticles in cosmetics, the US Food and Drug Administration provide a set of guidelines that they suggest should be followed.

I regularly read new scientific articles and journals regarding the toxicity of nanoparticles and based on what I have currently seen, I am not concerned about the use of the most common nanopartices in cosmetics (nano silica, nano zinc oxide, nano titanium dioxide, nano silver, nano platinum, nano gold, nano oil based liposomes).  I do think that by labeling nano products in cosmetics, consumers will now be able to make a choice as to whether or not they want to buy these products, and I will continue to choose to buy them until I see any new evidence that their use may cause more harm than good.


Can you increase your hitchhiking success using science?

Mr bean

Could Mr Bean use science to increase his hitchhiking success? (Image source (

Hitchhiking, it’s cheap, a great way to meet new people and a staple for many young students adventuring around the world during their summer holidays.  Although the obvious dangers of getting into a car with a complete stranger should be mentioned, I’ll admit I’ve taken the chance many times and been lucky in only having positive hitchhiking experiences during my world travels.

People say that hitchhiking is more of an art form and not an exact science, but as a scientist I wanted to know if I could increase my success rate of being picked up on the road side by sticking my thumb out armed with some published research.

In this weeks science spot on KiwiFM I discuss how the weather and the apparent size of your breasts (females only sorry) can increase your chances of success.  Click on the link below to hear the segment:

Experiment 1 – Just for the girls

In the paper “Bust Size and Hitchhiking: A Field Study” published in the journal Perceptual and Motor Skills, a 20 year old female who was rated as having “average physical attractiveness” by 15 male students was asked to stand on the side of the road wearing a figure hugging white shirt.  The female indicated that she was hitchhiking by holding out her thumb as cars drove by and two hidden researchers counted the number and the sex of the motorists that either drove past or stopped to pick her up. The experiments took place between 2pm and 6pm on sunny days in early summer to attempt to keep the conditions constant, however the female was asked to wear different “latex leaf” bras which changed the apparent size of her breasts from an A cup through to a C cup.

The results are as follows:

Cup Size A Cup Size B Cup Size C
Male drivers (n = 774) 40/268(14.92%) 46/256(17.79%) 60/250(24.00%)
Female drivers (n = 426) 12/132(9.09%) 11/144(7.64%) 14/150(9.33%)

Statistically speaking, only the mens behaviors were affected by the hitchhiker’s apparent breast size (p <.03). and the frequency of stopping during the cup C bra wearing was slightly greater than the B cup bra (p=0.09).  Interestingly the C cup bra results were significantly greater than those of the A cup bra (p<.01).

The likelihood of a woman driver picking up the female hitchhiker remained constant regardless of her apparent bra size.

One thing that I like about this study is the little note in the paper stating that a male observer was hidden close by to ensure protection against any possible threats to the females security.

Experiment 2

Sunshine or cloudy?  Which is better for hitchhiking?

Sunshine or cloudy? Which is better for hitchhiking?

If you don’t happen to be a female with some extra padding, then all is not lost.  The paper “Hitchhiking and the ‘sunshine driver‘” published in Psychological Reports tested the effect of sunshine on drivers willingness to give hitchhikers a ride.  This study involved 2 men and 2 women with a median age of 20 years who hitchhiked on both sunny and cloudy days when the weather was between 20°C and 24°C.

2864 cars drove past in the study and the results are as follows:

Male Hitchhiker Female Hitchhiker
Sunny Cloudy Sunny Cloudy
Male drivers (n = 1804) 35/4407.9% 25/4785.2% 64/42814.9% 45/4589.8%
Female drivers (n = 1060) 11/2524.4% 5/2661.5% 20/2667.5% 15/2765.4%

So it seems that sunnier days will help to increase your success in hitchhiking (p=0.001) and you are more likely to be picked up by a male driver than a female one (p<0.001) especially if you are a female hitchhiker (p<0.001).

So can science help your success in hitchhiking?

Well it seems that if you are a female with large assets who is hitchhiking on a sunny day, then you will have the best chance. I’m obviously not suggesting that girls go out and buy some padded bra’s to take on their next travel adventure, but the science does back up what some of us hitchhiking girls probably already knew.  As for the boys, eventually all of the hitchhikers got a ride up in the end, so don’t despair just keep that thumb out for a little bit longer.

Women in science rejoyce! LEGO announce the Female Minifigure Set!

LEGO just announced the winner of their LEGO Ideas Winter 2014 Review and as a female in STEM I’ll admit I did a little happy dance at the winning Female Minifigure Set.

Image: LEGO Ideas/Alatariel Elensa

Image source LEGO Ideas/Alatariel Elensa

LEGO actually do a really interesting thing and allow anyone to create, upload and then share an idea for a LEGO set that they want to see being made using their ideaLEGO page.  If the submitted idea receives 10,000 votes, the set goes to the review phase, where the LEGO review board chooses if it will continue through to actually become a new manufactured set.

The concept was actually submitted back in 2013 for the Fall 2013 review by a female geochemist in Stockholm named Dr Ellen Kooijman. The review process seemed to take longer than expected as LEGO state that “each concept has to be tested for stability, playability and safety before LEGO will commit to mass producing it”, so now it will be a Christmas gift idea as part of the Winter 2014 rollout with the set name ‘LEGO Research Institute’.

Ellen writes that she “designed professional female minifigures which show that girls can become anything they want, including a paleontologist, a chemist or an astronomer”, which are the three choices in the set.

I have to admit the dinosaur skeleton is swaying me towards the paleontologist, but to be honest I’ll probably buy all three!

To continue on with the female set Ellen has already designed anther series which includes a falconer, a geologist and a robotics engineer.

Image source LEGO

Image source LEGO

In addition to a zookeeper, a judge and a post girl.

Image source LEGO

Image source LEGO


Any toy that encourages girls to play in a way that encourages their curiosity and nurtures against typical stereotypes has my vote and I really hope that LEGO make the rest of the concepts that Ellen has designed.

The official LEGO announcement video can be seen here and they claim that these new figures should be on sale by August 2015.