Water, water everywhere but how safe is it to drink?
Posted on December 19th, 2010 by Alf | No Comments | Print | RSSIt is hard to believe, particularly for people coming from dry and drought-ravaged regions of the planet (like our state of South Australia), that water covers more than 70% of the Earth’s crust. It is also the largest component of the human body, averaging around 60% of the body weight of an adult male although the proportion is even higher in a 20-25 week foetus (greater than 80%). All of our organs contain large amounts of water, and the myriad chemical reactions occurring in billions of cells in these organs taking place in an aqueous medium. The blood that carries nutrients to the different parts of our bodies is mainly water, and our waste products are dissolved in water ie urine. Just about everything we eat contains large amounts of water, and many of us drink a litre of more of water a day. So, however you look at it, water is central to our life.
Unfortunately, while we can’t do without water, the same applies to every other living thing on the planet, including bacteria, fungi, and parasites. Some of these grow and thrive in water, including bacteria that cause cholera and other diseases. Another property of water is its almost unique ability to dissolve all sorts of substances. Its ability to dissolve gases such as oxygen is absolutely fundamental to the survival of fish in the sea and rivers. Similarly, carbon dioxide dissolved in water is essential for the survival of algae and other plant life that live in the oceans, rivers and lakes.
But, of course, it is not just gases that dissolve in water. The oceans contain large amounts of salts as well as many other materials while the rivers, a major source of drinking water for many people, contain all manner of dissolved salts as well as sediment derived from rocks and soil. Fertilizers, animal wastes, composts, pesticides, industrial waste, pharmaceuticals, antibiotics used in animal feeds, plastic components, and air pollutants all find their way into rivers and, eventually, into the ocean. Traces of some of these materials, termed “organic matter” because the molecules it contains, are mostly made up of carbon atoms, may be present in our drinking water. The amount of this organic material in our drinking water is not insignificant because levels approaching, or even exceeding, 4 milligrams per liter are not unusual. This means that, over a fifty year period, and assuming we drink one litre (around 1.6 pints) per day, we take in over 70 grams (2.5 ozs) of this material. Read the rest of this entry »
Plastic: Not so inert and harmless after all
Posted on December 7th, 2010 by Alf | No Comments | Print | RSSThe late twentieth century will no doubt be remembered as the period in which a revolution in information technology really began to transform the world with the advent of the internet, satellite technology, mobile phones and lap top computers, communication with almost any part of the planet was now possible. At around the same time, another revolution, perhaps not as technologically impressive, but nevertheless of great significance, was also taking place. The plastics revolution has resulted in the substitution of simple materials such as paper, cardboard, wood, and aluminium, with plastics. Indeed, such is the pervasiveness of plastic, it is hard to find any area of human activity where plastic is not used. And of course there are good reasons for this. Plastics are easy and cheap to manufacture (if environmental and energy costs are not included), stable, unbreakable, and light.
Most people are unaware of the extent to which plastics have really revolutionized our lives. The carpets, floor coverings, furniture, light fittings, kitchen utensils and aids, and mattresses, may contain plastics. Much of our clothing may be made of polyester or nylon which is a type of plastic. It does not end there because when we get into our car, we find plastic in a sizable proportion of the interior (eg floor coverings, front panels), the exterior, and under the bonnet. When we drive to the supermarket, we find plastic in the food packaging, in the shelving, refrigerators, light fittings, and floor coverings. And, of course, when we pay for what we have bought we may take our plastic card out of a plastic wallet or plastic handbag, and carry what we have bought to the car in plastic bags, perhaps even walking to the car in shoes with plastic uppers and soles. Back home, we find plastic everywhere both inside the house and in the garden. If we have children or grandchildren, we find it increasingly difficult to find a toy that is not made of plastic.
But, as with any new technology, while there may be benefits, there are also costs. Quite apart from the impact of the release of millions of tons of slowly degraded waste material on the environment, and its concomitant effect on animal and plant life, it is also very likely that our exposure to plastics has an impact on our health and wellbeing. But how can something that seems so inert and indestructible, affect our health? Surely, in order to do this, the components of plastic have to be taken up into our bodies? Read the rest of this entry »
