A minor but not insignificant factor in osteoporosis can be pollution in the environment, affecting your bone mass in two ways: the reduction of sunshine under murky skies (see vitamin D section on p. 96) and the toxic effects of particles of matter in pollution – the aluminium toxicity noted earlier, and especially high levels of lead, cadmium, mercury and zinc. When calcium in the body is low, it tends to be replaced by these other harmful minerals.
Lead. D. Bryce-Smith in Chemistry in Britain describes lead as ‘. . . one of the most insidiously toxic of the heavy metals to which we are exposed, particularly in its ability to accumulate in the body, and has been said to interfere with practically any life-process one chooses to study.’
When lead enters the bloodstream, about 10 per cent is excreted but the remainder is lodged in bone tissue. Lead can cross the placental barrier to a growing foetus and reach a nursed infant through lactation. It is well-known that high levels of lead in the blood can be fatal, but recent research has found that 30 micrograms per decilitre of blood can have an adverse effect – a level considered free of risk only two years ago. A safe level of lead in the blood has not been established. Unborn children are in danger of acquiring birth defects and children of one to three years of age are most susceptible to permanent damage. It can be absorbed into the body by inhaling, ingesting or through the skin.
Where is lead found? It is in the air, mainly from petrol and industrial processes, from burning coal or refuse. Lead is in food, from fertilizers, insecticides, pesticides and some ceramic glazes. It may be in drinking water, flowing through lead plumbing; and it is in lead-based paints, ammunition, fishing weights and some cosmetics.
What can you do to avoid it? Because children are most at risk from lead pollution, check around the home for old lead-based paint on walls (especially if it is chipping and peeling), or on painted toys, since youngsters tend to chew on paint chips. Unleaded paints are now available in shops for home decorators. In urban areas, lead accumulates in dust, so it is a good idea to do indoor dusting frequently, as well as sweeping porches, steps and driveways where children often play. Be sure that dirty hands are washed before food is prepared, and especially before eating. Buy fresh foods whenever possible, since metallic lead (mainly solder) gets into food during the canning process, particularly if the food is acidic. If you have to use tinned food, wipe the tops of cans carefully before opening; remove food promptly, without scraping the cans too vigorously, and transfer the contents to glass containers. Never store food or juices in tins. All unprocessed fruits and vegetables, from a greengrocer or home-grown, should be thoroughly washed in water or a mild vinegar-water solution, and outer leaves discarded, to remove pesticides, insecticides and contaminated soil as much as possible. If you take your own pie-shells and pastry-cases using pellets to weight the dough, use glass or ceramic beads or dry beans and not lead or aluminium shot. Discard old toothpaste tubes that sometimes contain lead – more recently, tubes are made of plastic.
If you have lead plumbing, use Water only from the cold water tap for the kettle or for food preparation, running it for a few minutes before using. And before installing a water softener, check that you have no lead pipes.
Controversy still surrounds the addition of lead to petrol, to increase the octane rating (in 1986, at the rate of 0.15g per litre), although the practice is a serious health hazard. Australia, New Zealand and the United States now have programmes for marketing lead-free petrol, and it is earnestly hoped that car manufacturers and the petroleum industry will soon reach agreements to ban completely the use of lead additives in the UK, EEC countries and world-wide. Meanwhile leaded petrol continues to be used and to cause concern.
Home potters use lead glazes because other safer glazes require firing at higher temperatures not always achieved with home kilns. If you are buying ceramics at a craft fair, or maybe in a foreign market, ask what kind of glaze was used. Coffee can pull the lead out of lead-glazed coffee mugs, for instance, and poison the person drinking it. Artist-potters may be exposed to glazes that contain the metals lead, cadmium and nickel; they are cautioned to read and follow the directions on labels of art material, use gloves and good ventilation. When glazing vessels intended for food and drink, use a lead glaze on the outside surfaces only, and some other non-toxic glaze on the inside.
Old traditional pewter may have a high lead content and should be avoided for drinking beer, cider or wines, or for storing fruits, pickles and preserves.
Although the sale of lead-containing cosmetics is banned in Britain, leaded eye make-up is still imported from the Indian subcontinent, and some medicines imported from the same area also have a high level of lead.
Cadmium. Cadmium is used in plating steel, iron, copper, brass and other alloys to prevent corrosion. It is used in storage batteries; as pigments in paints, enamels and lacquers. Poisoning can occur after drinking an acidic food or drink, such as lemonade, after preparation in a cadmium-plated can.
In Japan, cadmium poisoning is known as ‘Itai-itai’ disease, meaning ‘it hurts, it hurts’. In the 1960s, cadmium seeped downstream from toxic waste along the Jinzu River, contaminating drinking water and polluting rice paddies near the village of
Haginoshima. When villagers had had repeated pregnancies, severe bone disease developed in old age: calcium from their bones had been drawn off by each growing foetus, and replaced by cadmium, subsequently resulting in bones so weakened that they splinter with a sneeze. The Japanese cadmium dumping ended in 1971, but itai-itai disease is chronic; more than 100 villagers died, and other survivors receive benefits under the Japanese law devised to help people injured by hazardous waste or air pollution.
Closer to home, in Shipham, Somerset, where the village was built over old zinc mines, cadmium concentrations in the soil have been contaminating leafy vegetables and rhubarb. These villagers have now been cautioned to eat less home-grown produce to reduce their intake of cadmium. And in the Heathrow area near London, the use of sewage sludge on market gardens over a long period has increased the cadmium in lettuce and root vegetables. Cadmium is also known to accumulate in kidney meat and in brown crab; other shellfish is being carefully monitored by the Ministry of Agriculture, Fisheries and Food.
Mercury. Even in ancient Egypt mercury was known as a toxic substance, but was used for medical purposes. In the nineteenth century, a mercury compound was used to treat felt in the hat industry, causing poisoning with damage to the kidneys, tremors and other physical effects, hence the term ‘mad as a hatter’, and subsequently it was banned for that purpose. Today, under carefully controlled conditions, it is used in antiseptic salves, as a germicide, a fungicide, and in diuretics to increase urine flow. Because mercury compounds are presently used in fungicides for seeds, in water-based paints and in paper, the discharge of mercury-containing wastes into drainage systems is creating some concern. Build-up of mercury, through the ecological chain, in tuna, swordfish and salmon, has caused some governments to set definite limits on permissible levels in edible fish.
The Ministry of Agriculture, Fisheries and Food is monitoring the mercury content offish entering selected British seaports, and reporting to the D.H.S.S.’s Committee on Toxicity.
In the Mediterranean area, high mercury levels previously attributed to industrial wastes, have been found to be originating mainly in natural run-offs from mercury-rich soils, particularly from Spain, Italy, Yugoslavia and Turkey. Under the Mediterranean Action Plan, participating countries have banned dumping of the most dangerous wastes (mercury, DDT, PCBs, arsenic and radioactive substances), but eating raw shellfish in this region is still dangerous.
Zinc. The toxicity of zinc is lower, but still represents a hazard. Zinc is used as a coating for the protection of steel and the production of galvanized metal, frequently seen as a roofing material. It is in tyre production and in weedkillers. Zinc can occasionally enter pipes used for drinking water.
Approximately 63,000 chemical compounds are in common use, with 1000 new compounds added each year to that total. A recent study by the US National Academy of Sciences concluded that ‘of tens of thousands of commercially important chemicals, only a few have been subjected to extensive toxicity testing, and most have scarcely been tested at all.’ Is there any level of toxicity so low as to be harmless to humans? What is an acceptable risk? Many chemicals can cause cancer, damage to the central nervous system, liver and kidneys, from which it can be inferred that there is an effect on the proper functioning of these organs, impairing bone mineralization.
Write to your government representatives to express your concern; demand an acceleration in efforts to clean up the environment and ensure safe handling and storage of toxic wastes.
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