I guess one of the commoner reasons many of us grow our own produce is to avoid the pollution and contaminants that we fear may be found in some commercial fare. Of course fresh food tastes better, it is very economical, and we can have a choice of crops and varieties not usually sold in shops. Well versed organic growers will also know that organic food is not just better for you because of it's freedom of deliberately applied pesticides but also because of it's higher levels of scarce nutrients and vitamins.

But, and it is a worrying but, could we inadvertently and unwittingly be dosing ourselves unknowingly with all sorts of things we would really be better off without. In other words could growing your own actually be more risky than buying in? After all government agencies and major suppliers do run analysis and investigate likely residues to make sure that all foods are 'safe' as defined by their standards. Few of us have ever had a soil analysis done and I doubt hardly anyone reading this is likely to have their private produce checked for organo-phosphate residues, mercury or lead!!!

Naturally most of us are sensible and are careful of what WE put on our soil. And as our knowledge improves we slowly improve our understanding and desist from adding to our woes. However we may inherit or receive troubles from a very wide range of sources many of which do not immediately spring to mind yet need to be considered.

Only a couple of years ago newspapers featured articles about the alleged dangers of adding the contents of the vacuum cleaner to our compost heap. This centred around the likelihood of this containing considerable lead, rubber and asbestos from dust brought in on our shoes. A moments lucidity revels this as ridiculous- if the dust brought in on our shoes is a risk then heaven help us with the amounts blown into our garden!!!

Something like nine tenths of average vacuum cleanings is bits of human skin, hair and fluff off clothes. These may contain all sorts of undesirable residues including potential loads of disease pathogens and parasites (such as fungal spores of athlete's foot et al, fleas and flea eggs from pets and so on) but most of these are not likely to be a serious problem once composted. However if you use a lot of drugs, medications, lotions, hair dyes and so on then you might consider withholding your personal detritus from the compost heap. In particular if you take antibiotics do not add your urine to the heap as it may handicap the compost's micro-life.

People also get concerned about newspaper and printed matter. This used to be a serious problem however modern paper and modern dyes are considerably cleaner than they used to be (The newspaper industry does not want to be sued for inking your fingertips and clothes yet alone actually poisoning us. But glossy magazines have too much gypsum in their paper for it to be sensibly composted and likewise some of the colours may also be suspect.

In the same way paper and cardboard packaging ought to be de selected where it is waxed, lacquered, highly coloured -or as is beginning to happen; treated with fungicide and or bactericides. (Toilet roll tubes used to be good for starting off sweet corn and sweet peas but I have heard that some may be treated with fungicides and so are probably best composted or dumped.)

And one of my old favourites, carpet, may also be risky. When I first recommended old carpet laid upside down to kill weeds it was apparently safe. However it seems many modern carpets may well be treated with moth proofing agents and therefore are not safe. (Old carpets may also have been treated but it is probable much of the agent will have been removed with years of use and cleaning.) However I no longer recommend old carpet for use on cropping ground.

A much more serious worry is the past history of your garden. Obviously an ex nursery or small holding may have had old fashioned chemicals used in very high and frequent amounts. Lead arsenate and arsenite were very regularly used, mercury was also heavily used in seed dressings and compounds. Boron and other rare elements were also used as pesticides for everything from ants to rats -and their dead bodies then carried a toxic load in more ways than one. To say little about the countless tons of organo-phosphates used since W.W.II and the countless other garden chemicals sold to us as safe and now withdrawn! Previous gardeners may also have used large quantities, indeed as professionals watch every penny spent and only apply costly compounds if deemed economic it was the keen amateur who may have used excessive amounts of what are now known to be persistent poisons. Sewage sludge is another source of heavy metals but fortunately has rarely been applied to gardens.

Of course some areas are well known for having hazardous levels of certain elements from spoil from old mine workings. These used to be kept quiet but recent regulations have ensured councils and solicitors should be well informed and can advise a gardener as to the prospective risks of certain plots. However there is a big pressure to re-use these and other 'Brownfield' sites for housing. They may remove the topsoil entirely but I do not consider that is sufficient in the worst cases.

Worse, there are remarkable hot spots of radioactivity all about the country. Not from the nuclear industry (though I hold them to blame for far more than they admit to) but from the watch and dial industry. Radium and other radioactive compounds were included in phosphorescent paints for decades before we realized the hazards. You only need paint from one hand on a dial to give a seriously dangerous spot of intense radioactivity. And it is not just the old factory sites but also the homes of outworkers and of course anywhere a watch was dropped, damaged or a dial from a car or plane broken up.

Along with the glowing dials there is another hazard from more recent times, one make of telephone popular only a few years ago had a glow in the dark crescent made of a tube containing a radioactive substance. Allegedly countless thousands of these are stored somewhere waiting for a method of disposal. (-does anyone know where they are -sounds like an accident waiting to happen.)

There can be few gardeners who have not unearthed old dry cells as used by radio enthusiasts fifty years ago. These are full of nasty metal compounds especially manganese and zinc. Then there were the lead acid storage batteries though these were more often recycled some were still dumped to become long term polluters. And the earliest transformers, spark coils and similar were filled with some extremely toxic and very nasty liquids. Later ones used more modern nasties and were if anything worse, though regulations now usually prevents the worst of these still being used.

Indeed any garden, especially a midden or rubbish heap, may well contain any of the above, and of course tin cans (too much tin as well as the iron), lead glazes and lead glass from old pots and bottles, copper wire and similar redundant junk. And just pray nobody who once lived in your garden was an amateur photographer from the days when they did all their own developing.

The greenhouse or house boiler or range will also have produced tons of toxic ash, much worse in the old days with cheap coal full of sulphur. I doubt there are many gardens in the country with no flue or grate ash in them. Bonfires are another obvious source of both air borne pollutants and ash -but burning some rubbish may make it even more dangerous. We must all be aware by now of the serious risks of burning almost any plastic or rubber. But have you thought about the lead undercoat on those old window frames you once used for a coldframe? So all painted timber from an old house must be considered hazardous. And all modern timber likewise, painted or not, as it is now obligatory for it to be treated. Garden timber is also potentially hazardous as many of the older wood treatments contained either very poisonous elements and/or more complicated chemical preservatives. Burning these both liberates them and potentially alters them to more dangerous forms.

I'm often criticised for introducing car tyres into gardens. I did not. They were already being used for containers before I was born. I merely retold people how others were using them. However I really do not consider a tyre in the garden is more of a risk than those on the car in the drive. Once they start to degrade perhaps but they were designed to last. AND a car tyre is replaced because it wore down- the rubber dust produced is far far more dangerous and apparently eight tons or thereabouts falls on Londoners every day!

Cars also drip engine oil and belch fumes, these we know and fear, but few think of the asbestos that was used for nearly a century in their clutches and brakes. Reduced to a fine dust this asbestos has been permeating our entire country. (Asbestos board, roofing and insulation can all have added their quota if they have been improperly disposed of in your garden.) Relatively safe if undisturbed the dangerous fibres are released when the material is broken or degraded in any way.

Trains are if anything worse than cars. All the same criticisms apply to train oil, fumes, and asbestos but trains add one special risk all of their own. They dump raw sewage in the open air!!! Although some of the most recent rolling stock has tanked toilets the older stock does not "Please do not flush the toilet while still in the station" is still the order… Now fresh urine may not be pleasing but with the exception of hepatitis is not a horrendous health hazard. BUT fresh faeces dumped on the tracks is! Worse, when the train is moving the faeces hit the track at speed and are turned into an aerosol bomb that pollutes the track and all the surrounding area, and to add insult is sucked in through the air intakes to be breathed by the passengers.

Aeroplanes may also be dumping on you, vast quantities of fuel may be dumped as a safety measure before they land. But they also drop blue ice on you! Like meteorites chunks fall to earth from leaking toilets. Bigger lumps make the news, smaller ones melt unnoticed. Even satellites up in space are not risk free, once they age they slow down and fall. Again the larger chunks (including nuclear piles!) make the news but the smaller bits and all the burnt up materials just add to the atmosphere's burden.

The worst atmospheric risk is the fall out from nuclear tests. Fortunately things got so obviously bad by the early sixties that above ground testing was halted. However it was not in time. We all know how badly the Chernobyl disaster was and how it polluted huge areas. What few of us know is that the fall out levels in the early sixties was much much worse. Between Hiroshima and the test ban the great powers tested nuclear bombs at the rate of one every third day for nearly two decades. Then they boasted how many thousands of tons of Eniwetok, Bikini, et al had been lifted into the air!

If you get cancer your habits or your genes may well be at fault but in my estimation we are being made to feel personally responsible for what governments did to us. It only takes one radioactive particle on the skin or inside us to start a tumour. And these particles will still be floating around for thousands of years. To say nothing of the leaks from nuclear power stations, reprocessing plants and the rusting hulks of lost nuclear submarines.

Indeed the air can carry all sorts of pollutants from dusts from the Sahara to dissolved chemicals and crop spray residues. Grapevines are so susceptible to hormone weedkillers that they often suffer apparently reasonless distortion when all that happened was they caught a whiff of something. Crematoriums, power stations, and cement factories are all places I really would not want to be downwind of. Of course things are being improved but just imagine what was produced when a woodchip coffin covered in plastic laminate with plastic handles and a plastic liner containing a formalin and drug soaked body in a nylon suit and rubber soled shoes fitted with an early atomic heart pacemaker, mercury fillings and an artificial hip was being slowly roasted....

However the most surprising pollution I have discovered comes from a very unexpected source. We are aware of the problems of antibiotic resistance coming about from the abuse of these useful substances. We all fear their residues in non-organically reared meat and most of us are careful to avoid using antibiotics unless they are really needed. Of course some get through the system. If animals were fed antibiotics then it will be in their muck, although some will be broken down by composting these wastes some will pass through.

But potentially far worse is the unseen and untested for antibiotic load being carried by vegetable material. Russian research (see N.A.Krasil'nikov Soil micro-organisms and higher plants) has shown that antibiotics are produced in the soil and are taken up by plants. This can be either to their benefit or detriment. However from our point of view it would be better to keep such loadings to a minimum. According to their research antibiotics are broken down fairly quickly in healthy soil with a large microbial population. However if the soil is not so healthy with a low number and variety of micro-organisms then the antibiotic levels can rise to undesirable levels in both soil and plants. In other words; good rich organically tended soil will produce food with less antibiotic residues than will poor soil fed soluble fertilisers. But as antibiotics are rarely used in farming or horticulture I am not aware that any tests for residues in vegetables and fruits are ever done in this country. I've certainly not seen any results.

So finally, should we worry? Well the precautionary principle should apply and we ought to try and reduce all these risk factors to minimum's where possible. But as so many sources are involved with so many of them past events or totally beyond our reach then it is futile to try and deal with these. However we can be cautious over introducing any new hazards and limiting the extent of existing ones.

Washing all our crops, peeling those suitable, and controlling what we compost and burn will help considerably. Certainly all imported wastes, especially mucks, must be well composted before application as this will break down many complex chemicals and antibiotics. But it will not affect the heavy metal elemental and radioactive loads. Fortunately for us these, although horrendous, are relatively slight and if we eat well, get plenty of sleep and exercise and are healthy then we can trust in our bodies to do the best they can to preserve themselves.

And after all, things are getting better, regulations and rules may be irksome but they are slowly cleaning up the worst polluters, hopefully one day we will look back and think how crazy we collectively once were and how amazing it was we survived at all.