The most common heavy metal contamination of soil is from lead. Lead is a very common natural element and can be found in trace amounts in almost any soil on the planet. It's when it's present in high enough concentrations to become a potential health hazard that it becomes a problem. The most common places it will pose such a problem are around current and historical areas of mining, ore transportation routes, ore smelting plants, fossil fuel processing plants, coal fuelled energy plants, rubbish dumps, in large old cities where lots of vehicles used to drive around on leaded petrol, and where factories have been that use or once used lead in the making of their products. At one time there was a lot of factories using lead, it's quite astounding how much lead was once used, from batteries to paint, pipes to bullets, petrol to old toys, window frames and even old pewter drink cups among many other things. Once the lead is out in the open, it gets into the soil and it stays there.

Of course lead isn't the only heavy metal that can contaminate soil, it's just the most common one. Mercury and arsenic are probably the next most common and well known toxic heavy metals found in soil, and like lead, they are natural elements that can be found in trace amounts just about anywhere, but higher concentrations of them can be a health hazard. These more toxic metals are usually found in lower concentrations than lead, but as they're also more toxic than lead, they become a problem in smaller amounts.

The heavy metals you most don't want to find out are present in your soil in potentially harmful levels are the radioactive ones such as uranium and thorium, because that's a very different and much bigger problem than simply toxic ones like lead, arsenic, and mercury. Radioactive metals affect everything quite differently and require expensive environmental clean up measures and specialist advice on what to do if your soil report finds them at levels high enough to be a concern. There are other heavy metals that in high enough concentrations can be potentially harmful, and each different type of contaminate affects things in it's own unique way and needs it's own mitigation and clean up methods. Just keep in mind that it's not about the presence in the soil of a heavy metal, but of how much of it is there. If you've done a soil test and it tells you that trace amounts are found of any heavy metal, don't panic unless the report tells you that the levels are unusually high or potentially harmful.

As I have lived half my life in a lead mining town, I know more about lead than any other potentially harmful heavy metal, so I'll be concentrating this article on specifically high lead levels and how to manage that. If you need information about other heavy metals, I recommend contacting your local environmental management service or hazmat service for more information.

Lead in soil is usually present in the form of an extremely fine dust, so fine that you can't see it and it can suspend in the air for weirdly long periods of time for something so anatomically heavy. For this reason, if you have high lead levels in your soil, retire that leaf blower! The last thing you want to do is throw lead dust particles into the air where they can be breathed in, because getting lead dust in one's lungs is the fastest way for lead to get into your blood stream and cause high blood lead levels and serious health problems. You also don't want to be eating it, so wash hands before handling food, and wash any food that comes out of your garden well. Keep the lead in the soil, don't let it get into the air or into your mouth/stomach.

High blood lead levels are less of a problem for adults unless they've absorbed enough lead to actually start suffering from the early effects of lead poisoning, but for babies and young children high blood lead levels are a really terrible thing, as well as being much more susceptible to absorbing lead and suffering lead poisoning, even seemingly relatively lower lead levels in their blood can seriously affect their brain development and leave them with life-long problems, some of which can mimic and thus be misdiagnosed as autistic traits, and some of which can be much worse. Once lead is in the blood stream it takes years, even decades if high enough, to get rid of it. Sounds terrible right? Well, it is, but it's not something we can't learn to manage, mitigate, and live with. It just requires awareness of the risks, and doing things a little differently, and that may require a few habits to be changed.

If you find that you have high lead contamination in the soil in your yard, first see if you can figure out how it got there. This step is important because if it's there as a result of historic activities that no longer exist, it's far more manageable than finding out that the local coal electric plant down the road is still pumping tons of fine lead into the air each year to provide your town with electricity. If whatever caused the lead to exist in your soil in the first place is gone now, that's good news because it won't get worse. If whatever is causing it is still actively pumping out huge amounts of lead into the air without any mitigation strategies in place, my advice is to find somewhere else to live if you can, because it's only going to get a lot worse as time goes on.

Over the years there have been methods experimented with for removing and cleaning soil, some work, most don't, the ones that do are usually costly and beyond the scope of the average person to access and use or only serve to move the contamination from one place to another. There's a lot of misinformation about the topic that gets around, the most common one I've seen is the use of pill bugs, also known as woodlice. Yes, they absorb lead from the soil and hold it in their bodies... so do we, and most other living things... but the pill bugs are able to do it without getting sick from it. That's a good thing for them. However, once they die, they decay, and the lead ends up right back where it started, in the soil, with the rest of the dead pill bug. It's not a practical solution to the problem, which is why no one is raising armies of pill bugs and releasing them into the lead contaminated parts of the world. Growing sunflowers works somewhat as well, only the roots absorb the lead and we don't eat sunflower roots, that so that's fine, but then the sunflowers have to be removed with all their roots to remove the lead they absorbed, and then where do we put them? Once they die and break down the lead will be released again, so the lead is really just being moved from one place to contaminate another. All in all, if you have lead in your soil, there's not a lot anyone can do about it... but there are a lot of things that can and should be done to mitigate the health risks that it creates.

Once you learn you have to live with lead, be it historical residue or still being delivered daily to your yard courtesy of local industries, you'll need to adapt to doing as many of these things as fast as you can:

1. Educate your neighbours. Chances are, if you have high lead levels in your soil, they probably do too. You can't control what your neighbours do, and can't do anything about it if they decide to ignore you and do everything wrong and spread the lead, but you also can't blame them if they don't know about it, and they may not ever know about it if you don't tell them.

2. As much as you can't control your neighbours, you also can't control the weather. The wind will pick up dust and blow dust around as well. You might be able to renovate your home to minimise that risk by sealing up all the cracks, but even if you can't do that, you can at least make an effort to keep windows and doors closed and cover whatever gaps you can on windy days and those times when your annoying neighbour decides to use a leaf blower to create a small dust storm.

3. If you live in a very old house in a historically lead contaminated area, you might want to consider getting someone to check on the dust in the ceiling. There are professional services that can safely remove any lead contaminated dust that has collected and settled in the ceiling. If you're lucky, someone will have already dealt with problems like that before you moved in. A bit of no-more-gaps to fill in all the cracks will help slow down any dust falling into the house from the ceiling until you can afford to get it checked and removed if you can't deal with it right away.

4. As for the dirt in your yard, ideal would be to have all the contaminated soil dug out, removed, and replaced with clean fill. That's a big expensive job that most people can't afford. It's also pointless if everyone else in the area has highly contaminated soil and no one else is doing anything about it, or if a local industry is still contaminating the area, because every time the wind blows it'll be picking up dust from all over the place and dumping it in your yard and recontaminating your yard slowly over time, and you'll end up having to do it all over again eventually anyway. That being said, it's definitely worth doing if the lead levels are historic and are stupidly high, because it will take a very long time for the lead levels to get back to that stupidly high level just from a bit of historic lead dust blowing in from neighbourly areas.

5. If you have young children (from birth to under 7 years old), talk to their doctor and get them tested annually for blood lead levels. So long as your children's lead levels are staying low, you're doing everything right and everyone will be just fine. If your children's lead levels are starting to increase a little bit each year, even if they're still at harmless levels, you need to investigate how that increase is happening and do something about it before it gets harmful. As callous as it sounds to use your children as a regular lead level measuring device, they are far more susceptible to picking up high lead levels. Testing yourself won't give you any indication of the blood lead levels of your children, and they're the ones most at risk. If you're in a high lead risk area, get your young children tested annually to keep them safe.

6. Do as the Japanese do – outside shoes are for outside, inside shoes are for inside, and keep it that way. Don't go tromping through your house in shoes you've worn outside and don't let anyone else do it either, because you don't want to be bringing lead dust into the house that can be easily left outside by a simple shoe change. If you need to do work in the yard that involves digging around in the contaminated soil, such as landscaping or digging out an old tree stump, wear a dust mask and some outer clothing that you can strip off before entering the house and put it immediately into the washing machine and get in the shower before you go too far indoors.

7. Clean floors with a damp mop instead of sweeping them. With carpet if you have it, either invest in a vacuum cleaner that is specifically designed for capturing such extremely fine dust particles, or clean the carpet with one of those carpet cleaners that uses water or steam to wash the carpet as it sucks up all the mess. Unless you have toddlers crawling around on the carpet, if you don't have and can't afford anything better than a normal cheap vacuum cleaner, do not fanatically vacuum every day. In this situation, undisturbed lead dust in the carpet is safer than throwing it into the air via a vacuum cleaner that won't filter out the really fine stuff. In this situation, vacuum only when you really have to.

8. Get rid of the feather duster and always clean dust off surfaces with a damp cloth.

9. Never use a leaf blower. Rake up leaves gently, hose down cement and paved paths and drive ways, and don't run the lawnmower over areas where there's more dirt than grass. When mowing a lawn, mow it on the highest setting and leave the grass clippings evenly spread across the lawn, it'll look cruddy for a few days but they will break down and move down through the grass and cover the soil as a fine mulch – and will be very good for your grass, it'll grow thicker and more healthy for it, making it a better cover to keep the contaminated soil out of harms way.

10. Don't let kids or pets dig around in contaminated soil. If you have pets that love to dig and roll around in the dirt, don't let them inside the house without giving them a bath or shower first. If your kids want a sandpit to dig around in, that's fine, just make sure it's fresh clean sand and be prepared to replace it every couple of years (in my experience you'll need to do that anyway as kid's have an amazing ability to make the sand in their sandpit vanish into the rest of the yard rather quickly) and keep it well covered when not in use.

11. Cover the contaminated soil. It doesn't matter if you use concrete, pavers, pebbles, bark chip, mulch, garden beds, or ground cover plants including lawn, anything that will stop the wind from picking up the dust from the contaminated soil and blowing it around will do the job.

12. If you keep chickens, quail, turkeys, or other such poultry that like to scratch around in the dirt, either fully remove the contaminated soil from the area they will be living and replace it with at least 20cms (8inches) of clean soil, and every 2-3 years get that soil retested and if lead levels have built up in it, replace that soil once the lead levels are high enough to be of concern again; or keep the chickens on a cleanable non-soil surface (concrete, pavers, a thick layer of large pebbles, wood flooring, etc) covered in clean bedding. Chickens and other scratchy poultry love to fuss around in the dirt and will raise their own blood lead levels in doing so if they're scratching around in contaminated soil. Once their lead levels are high enough, their meat and their eggs will be contaminated with trace amounts of lead. Waterfowl such as ducks and geese don't have such a problem as they don't tend to scratch around in the soil, so a good thick lawn or similar ground cover such as clover, or a thick layer of bark chips will do good for them, but make sure to keep cleaning out their pond every couple of months so lead doesn't build up in it. Trace amounts of lead in meat and eggs isn't a problem if the trace amounts are small enough and no one eats huge amounts of those animal products, but on the flip side, very high lead levels and eating enough of the affected animal products can become a health risk. Before getting rid of your poultry if you can't do anything about them scratching around in the contaminated soil, ask yourself, how badly contaminated is it? Can you get your birds blood tested to find out how affected they are by it? How much of their meat and/or eggs are you consuming and how often? Remember, trace amounts of anything is only a problem when those trace amounts become large and concentrated enough to become a problem. Whatever you can do to keep your poultry safe will keep you safe as well.

13. If you're keeping bees, raise your beehives off the ground, cover the soil around the area, and try to keep the hive in an area that isn't so windy. Honey can gain some minor trace levels of lead from dust getting into the hive more than anything else, but it's in such tiny trace amounts it's not worth worrying about. That being said, every thing that can be done to reduce all the many trace levels of lead dust reduces the overall amount of exposure to it, so if there is something you can do easily enough, it's better to do it than to not.

14. If you have water tanks, don't drink the water, fill your duck pond, wash your veggies, brush your teeth, wash and rinse your dishes, and don't cook your food with the water from them. Lead dust will get on your roof and when it rains it will wash down into your tank and contaminate the water. You can use the water from water tanks to water the gardens with, and to flush your toilet with no problems, but don't consider water from a water tank to be clean potable water in any lead contaminated area. The vast majority of water filters on the market will not sufficiently remove the extremely fine lead particles from the water.

15. Keep good well-mulched gardens. If you can, used raised garden beds filled with clean soil. If you can't, don't panic, just be aware of the lead risk and only dig around in the soil after wetting it down to keep the dust down, wear a dust mask, and don't tromp the dirt that you get onto yourself into the house. Watering the garden, especially after a windy day, will push any fresh lead dust that has fallen onto the surface deeper into the soil where it can do less harm. Plants are fantastic for protecting soil from wind erosion, and some of them can even help a small way towards cleaning up the lead and removing small amounts of it from the soil.

16. Don't be afraid to grow your own food. Although some plants will absorb lead from contaminated soil, eating the food from those plants generally won't harm us. This is because most of the plant food we eat either comes from the fruits and leaves of perennial plants that are much less inclined to absorb lead in the first place, plants that will only absorb the lead into parts of the plant we don't eat anyway, or they're annual plants that simply don't absorb enough lead during their very short lives to become a problem. Generally speaking, you'd have to eat more plant matter than is humanly possible to be worried about high lead absorption from the plants we eat. That being said...

17. Always wash any and all food that is grown in your garden before cooking or eating it. We should always do this anyway because microorganisms are a thing, and animals including birds and insects poop on our food in the garden, but if you're growing food in a lead contaminated area it's even more important, because even though the plants won't generally contain enough lead to do anyone any harm, lead dust from the area can settle on the leaves and fruits, and root vegetables are going to be covered in it until all the dirt is completely washed away. Wash all edible plant matter really well before using it, because unlike many microorganisms, lead isn't neutralised and made harmless by cooking it.

18. If you're wanting to store root veggies like potatoes long term and need to keep the soil on them to do that, that's fine, just be careful how and where you store it. It might be a good idea to set up a suitable area in a shed or outhouse of some sort rather than keep them in the kitchen cupboard. If there's no other option than a kitchen cupboard, wrap each item in breathable paper to keep the soil contained and keep them in their own box in the cupboard until you're ready to wash and use those veggies.

19. There is an exception to points 16, 17, and 18, and that is if your soil is so extremely contaminated with lead that even your plants won't grow properly because there's so much lead in the soil it is blocking the plant's ability to absorb the nutrients it needs. It would require some rather extreme lead contamination for that to occur, but there are places that has happened. If your lead levels are that high, don't grow root crops at all until you can either replace all the contaminated soil with clean soil, or get raised garden beds filled with clean soil at least for growing your root crops in. If you're in this situation, for the sake of your plants you might want to consider replacing all your soil or growing in raised beds for all your edible plants just to be on the safe side as well as getting better results from your crops.

20. Lastly, maintaining a diet with plenty of easily absorbed iron and calcium can go a long way towards reducing blood lead levels if exposure to lead can't be sufficiently avoided or mitigated. The more iron and calcium your blood is busy carrying around, the less space there is for lead to join the party. For some people, this may require eating more animal products such as dairy, red fish, and red meat, because not everyone is capable of absorbing enough iron and calcium from plants to compete against lead exposure. But some people can absorb plenty of iron and calcium from plants with no problems. Everyone is different and we all function in slightly different ways, what works for one person may not work for another. That's just one more thing to be aware of and get tested for if a blood test for lead comes back with results that are a little higher than they should be, even if not at harmful levels yet. Lead builds up over time with exposure, so getting in all the iron and calcium you need early and regularly can reduce that lead build up over time and thus if you're lucky may stop lead blood levels reaching the point of becoming a problem. Prevention is better than cure, and lead contamination is one thing that couldn't make that statement more true, as there is no cure, only prevention, and some rather extreme treatments reserved for extreme cases.

The most important thing is, don't be scared of a bad lead result from your soil test and think there's nothing you can do about it and throw all your plans for gardening and growing your own food in the bin. Just like everything else in life that is scary, if you learn all you can about it, take the necessary steps and develop the practices you need to reduce your exposure, you'll be able to deal with it and live with it safely whilst still being able to do all the good things you want to do with your life.
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