Dr Farelly's talk had some long words and occasionally difficult science but its message was simple. It could not be said that the message did not also have political ramifications.
Her current research area is the political ecology of plastic waste so here, again, an obvious link. Her specific topic for the talk was "Endocrine disrupting chemicals in consumer plastic".
We are all sadly familiar with the mess caused by the overuse of disposable plastics. A major contributor to this are the millions of single use plastic bags emanating from supermarkets. They have a working life of as little as 15 minutes. Countdown and New World are to be congratulated on their commitment to phasing out single use plastic bags by 2018.
Eight million tonnes is a conservative estimate of the yearly amount of plastic finding its way into the oceans and more than half of this is disposable and non bio-degradable packaging.
The polluting aspect is amplified by the use of energy and fossil fuels in the manufacture of the plastic. It is a lose-lose system.
If current trends continue, by 2050 there will be more plastic in the ocean than fish by weight. Currently the annual dollar cost of pollution problems caused by plastic is estimated conservatively at $40 billion, which is greater than the profit generated by plastic packaging.
This plastic debris causes direct damage to marine life by entanglement and ingestion. Although it is distressing to see sea animals caught in plastic mesh, in the greater ecological scheme, this is a minor problem.
It might be easy to believe that this plastic will simply sink out of sight into the depth of the oceans. Not nice but at least not visible. Not so.
Sunlight and abrasion turns plastics into tiny particles referred to as microplastics which can move up the chain of consumption. Microplastics are now present in most tap water around the world.
They are present in rainwater, sea salt and most fish consumed in New Zealand. Microplastics are in the food chain. Pretty much everything you now eat or drink has a level of microplastics in it.
It is the effects of these microplastics, which go way beyond simple death by strangulation of marine mammals, that was the main message of the talk.
Plastic products leach out endocrine disrupting chemicals (EDCs). These are chemicals that interfere with the hormone system of the body. These hormones regulate metabolism, growth, tissue function, nerve function, sexual function, reproduction, sleep and mood amongst other bodily processes.
Dr Farelly described a bewildering list of EDCs. You will be able to learn about many of these on the Whanganui Science Forum website that will go live in the next few weeks so I shall describe just one of these here.
Bisphenol A (BPA) can leach into food from containers made with BPA.
Research has linked BPA to early puberty in females, reduced sperm counts, altered functions of reproductive organs, obesity, altered sex-specific behaviours, and increased rates of some breast, ovarian, testicular, and prostate cancers.
BPA researcher Frederick vom Saal said; "Pick a disease, literally pick a disease" and too much exposure to BPA will cause it.
Some EDCs occur naturally in some foods such as soya and chickpeas. However, these naturally occurring EDCs bind with blood proteins which greatly limits the amount reaching oestrogen receptors. Synthetic EDCs such as BPA bypass the body's barrier system and end up in cells.
Plastics were known to leach EDCs as early as the 1990s. Breast cancer researchers found tumour cell lines were mysteriously growing in petri dishes without feeding them oestrogen. It was found that as a result of the supplier swapping the glass petri dishes to plastic, synthetic hormones (EDCs) were leaching from the plastic.
Plastics have a property called hydrophobicity. This is the ability to repel water but absorb other molecules such as persistent organic pollutants (POPs). When microplastics are ingested, they carry these POPs with them and they can then be absorbed by the animals (or human) system.
POPs can remain in the environment for decades. As they move up the food chain these POPs become more concentrated and are found at the greatest concentrations in predatory birds, mammals and humans. Some POPs have been found in fish at 70,000 times the concentration in the water in which the fish swim.
Dr Farelly gave far more information on different plastics that are accumulating in the environment than can be given here. It is a very worrying situation. So what can be done?
There are many simple ways to reduce the effect, such as never heating food wrapped in plastic and avoiding canned food which has epoxy lining in the cans.
However, like smoking, the real answer is a social and political one. Education about the problem and pressure on government and retailers to eliminate single use plastic packaging. Drink from glass or metal containers not plastic and dig out that shopping bag your mother used when you were a kid.
■Frank Gibson is a semi-retired teacher of mathematics and physics who has lived in the Whanganui region since 1989.
