Lead Levels in Vegetables Grown Near Roads

Results of Russian study -- second study needs donations

Just received from Igor Prokofyev in Bryansk, Russia:

"Report on GROW BIOINTENSIVE (GB) experiments in 2012:

Effect of double-digging and composting on reduction of lead content in soil and vegetables"

Igor's report is at the bottom of this page showing how GB techniques result in 4% to 54% less lead contamination depending on which vegetable and how much lead contamination is in the soil.

For $1,000 Igor can continue the study for another year. Rincon-Vitova Insectaries is offering a $500 grant challenging others to supply the remaining $500 to help Igor continue this work with other vegetables common in the Russian diet. We need to know soon if we can fund this season's research.

Email your pledge to Carol Vesecky,

Director of Biointensive for Russia (BfR): cvesecky@igc.org.

Mail checks written to Ecology Action (for tax deductibility) to

BfR

913 Oso Rd,

Ojai, CA 93023

Biointensive for Russia also welcomes those interested in replicating the study in one or more plots in the US that seems relevant in view of trends to convert yards into food producing gardens.

Lead contamination in Russian home gardens is a special problem

Igor points out in his report that many Russian cities still use leaded gasoline. He does not explain what we understand to be an amazing amount of food grown by 71% of Russians at 35 million plots on more than 8 million hectares. In 1999, they grew 92% of their potatoes, 77% of their vegetables, 87% of berries and fruits, 59.4% of meat and probably eggs, and 49.2% of milk in their gardens. Reviewed in The Bovine, August 9, 2009.

Based on that data, we estimate that these gardens provide around 60% of their total food! They sure seem to be ahead of preppers in America! However, if the plot that they own is next to a polluted road, there is nothing they can do to avoid the pollution. Most Russians single-dig and use fertilizers rather than compost.

BfR wants to continue to help Igor gather the data to show Russian gardeners the benefits of GB techniques that move concentrations of lead away from the main root mass of plants, promote leaching, and bind soil lead on particles of organic matter in compost so it won't be taken up in the plants.

About Grow Biointensive (GB) techniques

The "Whys" of GB double digging

The "Hows" of GB techniques: How to Grow More Vegetables by John Jeavons costs $21.99.

Simpler version: The Sustainable Vegetable Garden, The Backyard Guide To Higher Yields and Healthy Soil costs $12.99.

These Books available at Bountiful Gardens

Online guide: Self-Teaching Manual (downloadable)

Quick summary of GB double digging with compost

Spread one inch of compost over new 3-5 foot wide bed at least 3 feet long, dig 1 ft trench at one end. If you put that soil in a wheelbarrow, you can use it to cover your next compost pile. Loosen next 12 inches with spading fork, dig second trench, slide shovels of soil into first trench. Some compost trickles into the trench. Avoid mixing or turning soil over. Fork bottom level of second trench and fill it with the top 12 inches from the third trench and so on to complete bed. For compacted heavy soil, more compost can be sprinkled in the trenches after forking.

GB compost piles are generally around 9 cubic ft built on forked soil starting with woody material, then layers of dry plants, green plants and kitchen waste, and soil. Manure and rock dusts are optional. Each layer is watered. To speed curing, pile can be turned in 3 weeks after temperature peaks. If turned once, it should be cured in 2 more months, depending on the weather.

Lead, why it is a problem

Lead is a priority toxin in urban environments. Lead paint, lead in gasoline, lead in car batteries, and lead pollution from industrial processes create toxic levels of soil lead in many cities. Lead poisoning in children leads to brain and nerve damage. http://en.wikipedia.org/wiki/Lead_poisoning

How much lead in food is OK?

World Health Organization sets the maximum lead limit in food for human consumption at 0.3 mg/kg. It appears that US limits bottled water to 5 mg/kg! Consumers Union found 25% of juices exceeded that level. China's limit is 0.2 mg/kg, maybe because there is more widespread lead pollution. Source An Iranian survey found lead concentration to exceed0.3 mg/kg for all vegetables surveyed. In the U.S., current lead levels in commercially purchased foods are in the range of 0.1-0.3 mg/kg.

A Cornell University extension bulletin explains that lead stays concentrated near the soil surface unless mixing occurs and that lead absorption is mainly into roots and leaves, not fruiting parts like tomatoes, corn, beans, squash, eggplant, peppers. In both Igor Prokofyev's and the Cornell extension studies lettuce takes up a lot more lead than other popular vegetables studied, but in Igor's study it could also be due to particles falling on a large surface area of lettuce. We don't know if he washed the surface lead off of the vegetables which can be done with a little vinegar &/or touch of soap in wash water. Water alone doesn't remove heavy metals fallen on vegetables. The bulletin explains that in soils with at least 40% organic matter there was no lead uptake even when lead was present at 3,000 ppm (otherwise a highly unsafe level of soil lead). The University of Minnesota also has a bulletin about lead pollution in home gardens.

Unleaded vegetables are an antidote

Fresh vegetables are a partial antidote for lead and heavy metal poisoning. Mung bean sprouts have a particularly high level of chelating factors that help carry lead out of the body. Home grown, fresh vegetables, literally at your feet, may offer a cure for the toxic city landscape. Learning how to garden to reduce lead and other heavy metal exposure is an important part of greening the cities – a transitional step to sustainability.

Soil testing labs

How to Grow More Vegetables recommends: www.timberleafsoiltesting.org located in SW Riverside County. Lead test $39; Cadmium, Nickel & Chromium $29 extra for each.

Timberleaf's combined basic + trace mineral test is $63 (BASIC: Estimated Nitrogen Release, Reserve Phosphorus, Available Phosphorus, Potassium, Magnesium, Calcium, Hydrogen, Sulfate Sulfur, Soil pH, Buffer pH, Cation Exchange Capacity, Soluble Salts and Sodium, Percent Base Saturation for Potassium, Magnesium, Calcium and Sodium. TRACE: Zinc, Manganese, Iron, Copper and Boron. )

Fruit Growers Lab in Santa Paula, CA, has pricing as follows:

Heavy metals test is $32 for sample prep + $24 for each element, such as lead. Total for one lead test=$56.

Panel of 17 elements by ICP* for $315, includes CAM* list: Antimony (Sb), Arsenic (As), Barium (Ba), Beryllium (Be), Cadmium (Cd), Cobalt (Co), Copper (Cu), Chromium (Cr), Lead (Pb), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Selenium Se), Silver (Ag), Thallium (Tl), Vanadium (V), Zinc (Zn).

*Inductively Coupled Plasma (ICP) atomic emission spectrometer is used to analyze CAM-17 samples. CAM stands for the California Administrative Manual, also known as the California Code of Regulations. CCR Title 22 section 66261.24 specifies the 17 metals that can qualify waste as hazardous. The analysis method is also known as EPA 6010B/7400. CAM-17 metals analysis does not differentiate between different valences of chromium, and does not test for Fluorine.

Report on GROW BIOINTENSIVE Experiments in 2012:

Effect of double-digging and composting

on reduction of lead content in soil and vegetables

Grassroots Alliance PERESVET, Bryansk, Russia

by Igor Prokofyev

In every Russian city, large and small, gardeners grow their own vegetables. Many of these gardeners assume that they obtain environmentally safe vegetables from their gardens. Unfortunately, people do not realize the impact the urban environment has on their garden plots. A huge problem in Russian cities lies in the contamination of soils with lead. The main source of pollution is automobile transport.

Unfortunately, many cities in Russia still use low-quality gasoline. This fuel contains lead compounds, which increase the octane rating of gasoline. Car exhaust is diffused several kilometers from the highway and contaminates the soil with lead. The soil accumulates lead and passes it on to plants; thus it enters the bodies of adults and children via the vegetables they consume. In humans, lead is the cause of many serious diseases.

Because Russia's medical services are poor, many chronic diseases are not well diagnosed. We can assume that people are aware that their gardens are contaminated by lead. Unfortunately, most gardeners do not have the opportunity to buy a new plot in a location remote from the city. Such land is expensive, and most people do not have money to purchase it. The garden is a source of food for them. Therefore, we need to offer urban people a gardening method that will prevent transmission of the lead contamination into the vegetables, and then into the human body.

Aim of experiment:

The experiment’s goal was to test the effect of the GROW BIOINTENSIVE (GB) Sustainable Mini-Farming method on the accumulation of lead by vegetable crops. The experiment's hypothesis was that certain elements of the GB method – double digging and composting – will reduce the contamination of vegetables in soils that are contaminated by lead. For the experiment, we chose three dacha garden plots that are very close to the highways of the cities of Bryansk, Karachev, and Orel. The traffic on their highways is dense, about 4,000-6,000 vehicles per day. One dacha plot was chosen in each city. The lead contamination of the soil was evaluated at the beginning of the experiment. For this purpose, three soil samples were taken from the top layer (0-20 cm) of each plot. Analysis for the total concentration of lead in the samples was performed at the Soil Testing Laboratory of the Bryansk region. The soil type in all three areas was sod-podzolic, with humus content of about 2 percent. At all three sites the maximum permissible lead concentration in soil (MPC, 30 mg/kg) permitted by the sanitary-epidemiological norms in Russia was exceeded. (The MPC for plants is 0.5 mg/kg (ppm) of dry weight.)

The three plots differed in their lead soil contamination levels: Plot 1 (Orel) was 57 mg/kg, Plot 2 (Bryansk) was 81 mg/kg, and Plot 3 (Karachev) was 101 mg/kg. Two types of beds were laid out at each site. The first type of bed was Biointensive. Certain elements of GB minifarming were used in their preparation – double-digging and composting – were done while the soil was prepared. The compost had been prepared the previous year the Biointensive way. Compost was applied to the Biointensive beds at the rate of five 5-gallon buckets per 100 sq. ft. The second type was conventional beds. They were prepared by the methods used by most gardeners in Russia (single-digging, application of complex fertilizers in amounts recommended by the fertilizer manufacturer). The two types of beds were located close to each other to avoid major differences in the levels of lead contamination. Both types of beds received equal sun hours and were given the same amount of water. The vegetables were harvested as they ripened. The crop samples were submitted to the Soil Testing Laboratory for analysis for lead content. The total lead concentration in both soil and plants was determined by atomic adsorption spectroscopy.

Results and Discussion:

Table 1 contains the results of laboratory tests of the soil and of the vegetables grown in the experimental gardens. The data presented in the table show that the vegetable crops vary in ability to accumulate lead in their edible parts. Radishes, lettuce, and onions accumulate lead the most, tomatoes the least. This can be explained by the physiological characteristics of plants. Based on these results, it is possible to make a list of vegetables that can be grown in the contaminated soil, and to develop recommendations regarding which plants should not be grown under these conditions. To do this, the experimental work must be continued.

Table 1: Lead content in soil and in vegetables grown in experimental plots (mg/kg) or (ppm), with percent reduction from Conventional to Double/dug, Composted (“GB”) Beds

Additionally, the data presented in the table clearly shows the positive effect of the GB mini-farming method. In all three plots, a decline was recorded in the lead contamination of the edible plant parts. Double-digging and composting reduce contamination of vegetables by 4 to 54 percent. The reduction in vegetable contamination depends on two factors:

1. The plant species . For example, in soil contaminated with 57 mg/kg of lead, its concentrations in onions is reduced by 54 percent; in radishes only by 10 percent.

2. The concentration of the contaminant in the soil . For example, the concentration of the lead in onions in soil contaminated at 57 mg/kg is decreased by 54 percent, at 81 mg/kg it is reduced by 13 percent, and at 107 mg/kg by only 4 percent.

To explain the reduction of contamination of vegetables brought about by the GB method, we studied a number of articles in Russian and foreign scientific journals. On the basis of published data we can assume that two factors contribute to the reduction of contamination:

1. Double-digging. Use of the technique promotes the dispersal of lead compounds throughout the soil profile. Moving soil from one trench to another during double digging helps to reduce the lead concentration around the roots, as some soil from the upper part of the first trench slides to the bottom of the next one and away from the main root mass. Also, the loose structure of the soil promotes leaching of lead into the deeper layers of the soil.

2. Compost. Scientific studies have shown that mature soil organic matter, or humus, can accumulate and bind soil lead. The humus particles in compost stick to lead and make it less available to plants. We can assume that with regular use of Biointensive farming and of compost, lead contamination of vegetables will decline.

The data elucidated above allows us to make the following recommendation to gardeners: Use more compost on soil contaminated with lead. Of course this is not the path to full sustainability, but it will help to reduce the contamination of soil with lead and to maintain health. With increased concentration of lead in the soil comes its increased concentration in plants. However, it can be concluded that the accumulation of lead in plants is slow, that is, when the accumulation of lead in soil is rapid, its contamination of plants proceeds more slowly. For example, when lead’s concentration in soil varies as greatly as 57 - 81 - 107 percent lead concentrations in the dry matter of plants vary only from 0.38 - 0.4 - 0.49 percent, or only about a 10 percent increase in plant contamination compared with a 100 percent increase in soil contamination.

Conclusions

1. Lead contamination of soil is passed into the plants growing in that soil. Vegetables accumulate lead in their edible parts.

2. The greater the contamination of soil, the greater the contamination of vegetables.

3. Lead accumulation in plants proceeds more slowly than increase in concentration of contaminants in soil.

4. Vegetables accumulate lead in their edible parts in varying amounts. There are plants with a high capacity for accumulating lead (onions, radishes), and those that accumulate less of the contaminant (tomatoes).

5. Use of the GB double-digging and composting techniques reduces lead contamination of vegetables by from 4 to 54 percent. The extent of reduction of contamination in vegetables depends on the plant species and on the concentration of lead in the soil.

6. Double-digging and composting reduce the availability of lead to plants.

7. Gardeners who grow vegetables in soil contaminated with lead should be encouraged to use more compost and to practice double digging.

Author: Igor Prokofyev <igor.prokofev@gmail.com>

Experiment gardeners: Bryansk – Alexander Gorbachev,

Karachev – Viktoriya Grib, Orel – Nina Vratskaya

Translator: Carol Vesecky cvesecky@igc.org

Note from Carol: Do get in touch if you would like to collaborate with PERESVET on this year’s experiment, or in future years! I would be thrilled to facilitate!