proximity of garden to traffic

[DrakeMaiden]

Lead is somewhat persistent in the soil, so I would not assume it is safe just because we haven't had lead in our gasoline in 30 years.

We dont usually think of our gardens as dangerous or toxic,
but unfortunately, some garden soils do contain moderate to
very high levels of lead. Garden soils contaminated with lead
pose a serious health risk. The risk is primarily from
contaminated soil brought into the home on clothing, shoes
and tools. The soil becomes mixed with housedust that is
inhaled or ingested. This can result in dangerous increases in
blood lead levels, particularly in infants and toddlers. Lead
may also be ingested from contaminated soil clinging to
vegetable crops. However, lead uptake by plant roots and
deposition in edible plant parts is very low, even when soils
have a very high lead content.

(University of Maryland Extension )

This is the first time I've read anything that suggests lead can be rinsed from food crops, so I find that interesting.

I think if you are in a small town you are less likely to have high levels of lead, compared with a city.

There are some plants that will absorb lead from the soil, like sunflowers, if I remember correctly. But I have heard many times that lead in the soil near roadways is something important to consider when vegetable gardening. I, personally, would test for it anyway, before putting veggies in. JMO. Some information about the health concerns with lead.

 

[DrakeMaiden]

Here is some more information, from the Washington State University Extension about how lead from gasoline contaminates soil. I highlighted in bold what I thought was most important to take away from this publication. Let me also emphasize that it is my opinion that in a small town, you probably don't need to be too worried about soil lead contamination, but I want to post this in case someone else wants this information.

. . . About 75% of gasoline lead was emitted from exhaust pipes; oil or internal surfaces of the engine and exhaust system trapped 25%. The lead-rich exhaust dust fell directly onto soil near the road or blew a short distance first. Gasoline-derived soil lead is highest adjacent to roadways, parking areas, and driveways. Lead particle size and soil lead concentrations drop off quickly with increasing distance from driving surfaces; however, gasoline lead often has accumulated in more distant soils near structures that interfere with wind patterns. The wind-transported lead particles struck and stuck to houses, trees, and other barriers, and eventually were washed into the soil by rain. As a result, soil lead can be high around houses not painted with lead-based paint or those not adjacent to roads. Soil lead concentrations typically are higher near heavily used roads than near less traveled roads. Some states banned leaded gasoline as early as 1986. Washington continued to allow leaded gasoline until the end of 1995, when it was banned nationwide.

Soil lead typically occurs as minerals of very low solubility or as positively charged ions strongly bound to soil particle surfaces. Lead solubility is particularly low at high soil pH and in the presence of high soil phosphorus. Lead normally has very poor mobility in soil. Most surfacedeposited lead resides in the top few inches of soil unless the soil profile has been physically mixed due to tillage, digging, or some other disturbance. In this case soil lead redistribution can occur throughout the depth of mixing.

Suspect soil lead contamination if the garden is within 100 feet of roadways and parking areas, particularly near high-traffic routes.

The potential toxicity of either lead or arsenic in plants and soils depends on many factors. People vary in susceptibility to lead and arsenic, due to genetic makeup, type and amount of
exposure, general health, and age. Lead and arsenic in plants and soils occur in a variety of chemical forms, called chemical species, which have different toxicological properties. Most studies of lead and arsenic in plants and soils report only total concentrations of these elements because it is difficult to accurately and inexpensively quantify the distribution and amount of chemical species. The inherent variation among people, plants, soils, and behavioral factors greatly complicates predicting the relative lead or arsenic hazard of food plants and contaminated soils.

Concentrations of lead and arsenic in soil may be 10 to 1000 times greater than their concentrations in plants growing on that soil. Because of this, failure to remove soil particles that adhere or become trapped on the outside surfaces of garden crops can substantially increase dietary lead and arsenic obtained by eating garden plants.
Wash garden crops grown on lead- and arsenic-enriched soils with water before bringing them into the house. This removes most soil particles, reduces the lead and arsenic content of the crops, and reduces the transport of soil lead and arsenic
into the home.
Once you have brought the produce inside, wash it again carefully, using edible soap or detergent (sold at many supermarkets), water, and a scrub brush to remove
remaining soil particles. Pay particular attention to crops like broccoli having rough exposed exteriors that can trap soil. Leafy plants having large surface areas (such as lettuce and swiss chard) can trap and retain large quantities of dust.
Pare root and tuber crops (such as potatoes, carrots and radishes) and discard the parings.
Do not compost unused plant parts, peelings, and parings for later use in the garden.These practices will reduce the lead and arsenic content of harvested home garden produce to the lowest possible levels.

The distribution patterns of lead and arsenic among various plant parts is highly variable. Seeds and fruits typically have lower lead and arsenic concentrations than do leaves, stems or roots. Roots and tubers usually have the highest lead and arsenic concentrations, with the skin having higher lead and arsenic concentrations than does the inner flesh. The lead content of
roots correlates more closely to soil lead than does lead in leaves or stems, possibly because roots tend to retain absorbed lead and not transport it higher up into the plant. Tree fruits such as apples and apricots contain very low lead and arsenic concentrations. Contamination of plant parts by lead- and arsenic-rich soil or dust can increase the apparent lead and arsenic content of that plant.

 

[simple life]

Not sure if this would make a difference but if someone is concerned about using the existing soil in their yards why not have some new soil delivered.
If the lead issue is from when gasoline still had lead in it and not from traffic that is going by your place now then I would think doing raised beds with new soil will be safer.

 

[DrakeMaiden]

That is right, Simple life, that is the best thing to do, but the original poster seemed concerned about how expensive raised bed gardening might be.

 

[Augustmomx2]

Check with your local County Health Department & see if they offer free lead testing. I work for ours and we do test houses, items, soil, etc all for free. I minored in Enviornmental Science and from what I can (vaguely) remember, lead does stay in the soil for quite awhile. Though, it sounds as if your road is not highly traveled vs a highway for example. The amount of lead that would have been emitted would be minimal. Plus, if you think about all the roads and all the gardens that are near roads, 1/3 of us would have lead-poisoning by now. You have to be consistantly exposed over a period of time for it to have an impact. You can also have your blood tested as well, if you are still concerned, after you consume your veggies from your garden. HTH

I say go for it! I live 3 houses away from a major interstate and no probs w/lead. Our neighbors are right next to the interstate and they have had a garden for years. They do not seem to be exhibiting any behavior that would indicate lead poisoning.