Question from Emily of Cloverdale, California: 

I felt really strange (a bit of a headache) playing tennis today and realized someone was fertilizing the plants (on a riding machine). We live in a planned community with shared lawns and gardens. My husband asked the gardener for the ingredients. They are: nitrogen, ammoniacal nitrogen & urea nitrogen, phosphate, potash, magnesium, sulfur, copper, iron, manganese, molybdenum, zinc. How can I find out how toxic this fertilizer is?

Answer from *faircompanies

You have reason for concern. Toxic fertilizers are a big problem. Public advocacy group CALPIRG studied 29 fertilizers from 12 different states testing for 22 toxic metals- all linked to either ecological or human health hazards- and found every single fertilizer had traces of these dangerous substances.

If you’re wondering why these products aren’t banned, according to CALPIRG, there is no single law for regulating the toxicity or labeling of fertilizers. “Rather, myriad hazardous waste laws and regulatory bodies are responsible for various aspects of the practice of recycling industrial waste into fertilizers, often with little enforcement or oversight. As a result, the fertilizers we use on our farms and gardens contain high levels of toxic metals that are also not listed on the label.”

Since fertilizers are a neglected industry when it comes to regulations, there may be hidden contaminants in your fertilizer, but we can only work with what was listed on the label. Of those listed on yours, some of the ingredients, like nitrogen, are harmful to the environmental- both because in its production CO2 is released thus contributing to global warming and also because it is harmful when it gets into our water supply. 

More pertinent to your health question, there are others on your list that were specifically noted on the CALPIRG study as being hazardous to human health. Three of the ingredients from your fertilizer showed up on their list with the following “known and suspected health effects”:

• Copper: listed as possibly causing cancer as well as “suspected respiratory, reproductive, gastrointestinal or live, developmental and cardiovascular toxicant”
• Manganese: “suspected respiratory, reproductive, gastrointestinal or liver and neurotoxicant”
• Molybdenum- “suspected neurotoxicant” You have cause to be concerned about this fertilizer.

I’m not sure how much control you have over what the gardener uses for your community gardens, but there are more environmentally-friendly alternatives to chemical fertilizers. Even if just for your own yard, you can follow the tip sheet published by The Union of Concerned Scientists.

At the Garden Shop

1. Choose a plant-specific organic fertilizer designed for what you are growing. Different plants require different nutrients, even in the same garden.

2. Use slow-release organic fertilizers that nourish as they decompose in the soil. Most contain fish meal, bone meal, or blood meal derived from food-processing waste. Others include fruit and vegetable waste, kelp, and earthworm castings.

3. Apply a liquid organic fertilizer when plants are in need of a quick boost. These consist mainly of seaweed and fish-processing wastes.

4. Avoid fertilizers made from municipal sludge (also called biosolids). These are often labeled organic, but have been found to contain heavy metals and other toxic chemicals that can build up in your soil.

At Home

5. Make your own nutrient-rich soil supplement by turning food wastes you would otherwise throw in the trash into compost. An inch or so of compost added to your garden each year is often all you need to maintain healthy soil.

6. Dry some coffee grounds and scatter them around plants that need a nitrogen boost. Your local coffee shop may be willing to give you its old grounds-it never hurts to ask!

7. Provide additional calcium for your soil by spreading dried, crushed eggshells.

8. Make your own liquid fertilizer by mixing seaweed—an excellent source of potassium—and water in a container and letting it decompose for about two months. Since the resulting liquid will be concentrated, you’ll need to dilute it before adding it to the soil.

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