Contamination of Food
Grown in your garden

There has recently been some concern over such products as treated lumber or used motor oil coming into contact with garden soil and possibly contaminating vegetables grown in the soil. There are many types of gardens including home gardens, commercial gardens, display gardens, and vegetable gardens. No two gardeners use the same techniques when growing their plants, but no gardener should ignore the possibility of contaminating the soil. There are many steps that can be taken to minimize the possibility of garden contamination. Pressure treated lumber containing arsenic, copper and chromium (CCA) may be used safely in food gardens. The arsenic, copper and chromium do leach into the soil over time, however, and may be transported into food crops grown close to the treated lumber. To prevent possible uptake by food crops, do not grow them within 6" of treated lumber. See the first link below for a more detailed explanation. The ashes from burned treated lumber, houses, or buildings should not be mixed with garden soil either. Dumping hazardous garbage such as any product which is labeled WARNING, CAUTION, POISONOUS, TOXIC, FLAMMABLE, CORROSIVE, REACTIVE or EXPLOSIVE, into garden soil should also be avoided. Dumping used motor oil into any soil should be avoided, especially into soil that is used for gardening.

Please see these other EXTOXNET FAQs subjects:

• Questions About Gardening and Pesticides
• Naturally Occurring Toxins as Pesticides

Here are some very informative external links that pertain to gardening and contaminants in your garden:

• Using Treated Wood Around the Garden
• Lead Contamination In The Garden, HYG-1149-93
• Colorado State University Tips - Fresh Manure can lead to e. Coli Contamination in Food Gardens
• Oregon State University - What tiny critters live in your garden soil?

References

1. Larsen, EH: Moseholm L; Nielsen NM. Atmospheric Deposition of Trace Elements Around Point Sources and Human Health Risk Assesment. II. Uptake of Arsenic and Cromium by Vegetables Grown Near Wood Preservation Factory. Science of the Total Environment, 1992 Sep 25, 126(3):263-75.

This page written and prepared by B.T. Johnson, January 1998 UCD EXTOXNET FAQ Team.