Pesticides (which include insect killing chemicals, as well as weed killing chemicals) are toxic by nature. For humans, exposure to very tiny amounts can not only cause cancer, but can cause birth defects, nerve damage, genetic damage, reproductive damage, immune system disorders and more.

One of the big uses of pesticides in the United States is in home lawn care and home gardening. If you don't want a 'natural' landscape, you can still have a beautiful lawn and garden through using least toxic gardening. It's easy to start. Here are several effective ways to get rid of dandelions or other broad-leafed 'weeds' in your yard without using toxic chemicals.

1. Dig them out - 'old-fashioned' but if you (or a willing friend) can do this, it still works!
2. Use a cordless electric drill and a "Dandelion Terminator" and drill your dandelions out - in about 6 seconds per dandelion. This nifty tool is worth its weight in gold. It's no longer available from the manufacturer, but it shows up on eBay periodically. Price for one still in the original packaging on eBay averaged around $15 (not including shipping) as of October, 2012
3. Fill a spray bottle with a mixture of 1 cup vinegar and 1/4 cup lemon juice. Spray directly on the weed when the sun is out (be careful not to spray plants you want to keep!). You may have to spray a weed two or three different times, but the sources that recommend this say it works quite well.
4. Fill a spray bottle with straight vinegar and spray directly on weeds during a warm sunny day. My neighbor tried this on his plantain weeds, and totally eliminated them. We tried it and wiped out a huge patch of plantain with one try. It will kill dandelions too, but not as well.
5. Pour boiling water directly on the weed (be careful to not scald yourself). This works especially well for weeds in sidewalk cracks.
6. In the spring, before the daffodils bloom, use corn gluten as a pre-emergent weed killer and fertilizer on your lawn. The University of Iowa ^1,2,3 has found that corn gluten (a by-product made when processing corn for food) is as effective as any chemical pre-emergent herbicide - and as safe for us to be around as a package of corn meal. It is available now even in 'big box' retail stores, and is widely available through organic gardening catalogs.
7. Carefully use a fatty-acid based herbicide. Safer makes a product called "Safer's Superfast Weed and Grass Killer." This product is non-selective - it will kill all plants - so don't spray it near plants or grass that you want to keep unharmed. Be careful to read the label carefully before you use other fatty-acid based herbicides - some of the other competing products apparently use petroleum-based inerts, and some even mix in synthetic pesticides.
   Although Safer gives it a pretty broad spectrum of effectiveness, Peaceful Valley (a popular organic gardening and farming supplies retailer - phone: 888-784-1722 or http://www.groworganic.com) says that Safer's Superfast "works best on young, actively-growing annuals seedlings" - "it is not effective against woody perennials." ⁴
   If the weed has a deep taproot, it may need re-spraying. The most effective way to spray is to spray the entire plant during the heat of day in warm, dry weather.
8. Use a weed-flamer. Flaming will work on annuals, perennials, trees and vines. If you have chemical injury, and are bothered by propane, you want someone else to use this for you!
   Weed flaming has re-emerged because it is as labor effective as hand-spraying plants, "can be done when fields are too wet to cultivate, and does not bring dormant weed seeds to the surface."⁴ Flaming works by using the heat of a specially-designed propane burner to "boil" the water in the cells of the plant - takes about two seconds per plant. You do not set weeds on fire with a flamer. Obviously, you need to familiarize yourself with this equipment and how to use it safely before heading out into your lawn and garden! We've found flamers at our local Ace Hardware, and at our local farm supply stores. On the web, Peaceful Valley has a good selection of flamers. For home gardeners, they have a Primus Gardener Flamer that weighs only about 2.5 pounds total (tank, and the long wand) for around $40.00. For larger acreage, their "Red Dragon Hand Held Flamer" is priced at around $70, with an added-on "Flamer Squeeze Valve" (which makes it much easier to turn off and on) for an additional $45. A flamer is a once-in-a-lifetime purchase; the refillable propane bottles run a couple of bucks.

I've just scratched the ways you can handle all sorts of weed problems in a non-toxic fashion. The University of Iowa Integrated Pest Management Website is full of good articles that can help you address all sorts of lawncare issues, from non-toxic mole treatments, to moss problems in turfgrass, weed and insect control. Not all their articles exclude use of synthetic pesticides, but most do and are based on research carried out at major universities. Happy gardening!

¹Christians, Nick, PhD, University of Iowa, 1995. "A Natural Product for the Control of Annual Weeds." Golf Course Management: 71-72

²Christians, Nick, PhD, University of Iowa, 1995 "Greenhouse Screening of Corn Gluten Meal as a Natural Control Product for Broadleaf and Grass Weeds." Hortscience 30(6): 1256-1259.

³ University of Iowa IPM website

⁴Peaceful Valley Farm Supply Catalog