It may be versatile, durable and endlessly useful, but the once revolutionary plastic is beginning to fill Earth's oceans, posing a threat to marine life great and small.

Plastic has thousands of uses, its versatility and virtual indestructability practically unmatched in the world of synthetic materials. Since first developing plastic in 1907, we have melded and moulded the material to fulfil our needs and desires. From bags and milk bottles to agriculture and transportation, plastic is everywhere, useful and convenient. But we could be yet to realise the true cost of the synthetic behemoth we have created. Both land and sea are affected by plastic waste, mainly because it is so durable. It isn't just large pieces that pose a threat, however - microplastics are amassing in colossal quantities, sometimes in parts of the ocean that have never been seen by humans before. Marine biologist and microplastics expert Dr Lucy Woodall is a scientific associate at the Museum. Currently a researcher at the University of Oxford and Principal Scientist with Nekton, Lucy sheds light on just how deep our plastic problem is. The plastic planet Plastic is everywhere, and the ocean is awash with it.

According to figures published in 2015, from the surface all the way down to the deep sea, a gargantuan eight million tonnes of plastic amasses each year. Lucy says, 'These figures come from what we know goes to landfill, and what is known to go through other pathways - for example it gets burnt and recycled. We then assume that the rest of it ends up in the ocean.' Scientists have been able to calculate the quantity of plastic in the ocean by extrapolating from the amount collected in nets during their studies of the surface. 'It's relatively easy to see what is on the surface, but we don't know exactly what is floating mid-water or on the seabed,' says Lucy. 'A lot of my research is looking at the seabed, but we don't have enough data to be able to estimate the figure there yet.' A threat to marine life Microplastics, one aspect of the world's plastic problem, are pieces of plastic less than five millimetres in length, according to a universally accepted description from the USA's National Oceanic and Atmospheric Administration. 'We have a maximum size, but there is no minimum limit - they can become small enough to be classed as nano, so when you can't see them anymore,' says Lucy. From the largest pieces to the unseen, plastic is affecting life in the deep blue.

'You have the problems of ingestion and entanglement, but they can also be used for organisms to raft. Animals can use plastic as a conduit to get from one side of the ocean to the other.' 'This is potentially damaging if you get something non-native coming in and thriving. We know invasive species are bad terrestrially, like in Australia with rabbits. Less is known about this in the ocean, although it is just as damaging. One well-known example of this is lionfish in the Caribbean.' Plastic also has the ability to carry pathogenic microbes across the ocean, potentially impacting life as it travels. It can also act like a sponge, pulling in other chemicals. Lucy explains, 'Some organic pollutants are hydrophobic, and sit on the surface of the water. They want to get into the plastic away from the water, so you end up with a lot of them concentrated in the plastic. 'If that plastic then gets ingested, what happens to those chemicals? Some are released in the organisms when they are ingested.' Studies have shown that this significantly increases the concentration of organic pollutants in an animal, compared with organisms that haven't eaten plastic. Munching on microplastics Plastic is virtually indestructible - a virtue which helped make the material such a commercial success. Aside from being incinerated, it is a problem that will almost never go away. Left to itself, plastic will get infinitely smaller, but never fully disappear.

Lucy says, 'Microplastics are probably in every food we eat. They're in my cup of tea. I am breathing them in. We are exposed to them every day. 'But even if we stopped all plastic from going into the environment tomorrow, we would probably see an increase in microplastics. This is because some plastics come into the ocean when they are small, but most of them degrade into fragments from other large items. ' One issue is that there are many products that are not commonly known to be made, at least in part, of plastic. Lucy explains, 'Cigarette butts, babies' nappies, insulation - a lot of the products we make are made up of lots of different types of materials that are all connected together, so it's really difficult to break them up to recycle them. 'This is a human made problem, and what we need to do is start stemming the sources.' The microbead ban Plastics are now in parts of our oceans that humans have never seen.

Lucy says, 'For some of the places I go to as a researcher I am lucky enough to be the first human ever to see that bit of seabed, and I will still find bits of plastic.' 'We need to think beyond clean-up. You cannot strain every bit of ocean, and even if we could, you would be getting rid of all the biology, making it useless. 'We need to think about plastic before it gets into the ocean. We need to make sure there is appropriate waste management. 'Then we need to look at what we do every day. We need to value plastic. We should be buying it, not just for the cost up to now, but actually buying it through to the end of its life.' By the beginning of 2018, the long-awaited microbead ban should come into effect in the UK, preventing companies from producing wash-off cosmetic products that contain plastic particles. Products that include these purposefully manufactured microplastics, such as exfoliating scrubs and toothpastes, will not be purchasable from June 2018. Although this is a step in the right direction, it is not the end of the discussion on plastic use and waste. 'Microbeads in cosmetics are a tiny, tiny proportion of all plastic. They account for less than 2% of microplastics in the ocean, and that is an even tinier proportion of our general plastic problem,' explains Lucy. 'One-use plastic items and packaging are a much bigger problem. The next thing the government is looking at is things like plastic water bottles and one-use cups.'