Safe Fertilizer Information Institute

- California Dept of Agric., Evaluation of Heavy Metals & Dioxin in Inorganic Commercial Fertilizers and California Cropland Soils, 2004.

- Chang, Page & Krage, Dept of Environmental Sciences, U of California-Riverside, California Dept of Food and Agric., Role of Fertilizer and Micronutrient Applications on Arsenic, Cadmium, and Lead Accumulation in California Cropland Soils, Nov, 2004.

- Chang, Chen, Bar-Yosef, Page, & Kim, California Dept of Food and Agric., A Generalized Trace Element Mass Balance Model for Cropland Soils: Arsenic and Cadmium, Jan, 2004.  Note: A pre-condition for this model to apply is that the land also receives regular phosphorus (P) fertilizer application.  Other studies have shown that phosophorus acts as a limit to uptake.  If the farmer stops applying phosphorus, would the 'safety' regulations (such as California's) based on using this model still be 'safe'? 

- Curtis, Lawrence R. & Smith, Brian W., Dept. of Envtl and Molecular Toxicology, Oregon State U, Corvallis, OR. Prepared for Oregon Dept of Agric., Heavy Metal in Fertilizers: Considerations for Setting Regulations In Oregon, Aug 2, 2002.

- Washington State Depts of Agriculture and Ecology, Levels of Nonnutritive Substances in Fertilizers: Report to the Legislature, Dec 2007. Listing regulated metals content for all fertilizers sampled. Also noting 101 fertilizers were sampled between 11/1/05 and 10/31/07, 2 failed for exceeding cadmium standard.

     Another article on the dangers of Ironite.   Excerpt: The identification of As in oxidized Fe oxides and Pb as PbSO4 is in disagreement with the dominant reduced phases previously reported and suggests As and Pb contained within the mine waste-derived product are more bioavailable than previously considered. ... The observations from this study indicate As and Pb exist as oxidized phases that likely develop from the beneficiation and processing of mine tailings for commercial sale. The potential release of As and Pb has important implications for water quality standards and human health. Of particular concern is the quantity of As released from mine waste-derived products due to the new As regulation applied in 2006, limiting As levels to 10 μγ L[-1] in drinking water.

"Framework for Cumulative Risk Assessment, a report developed under the auspices of the U.S. Environmental Protection Agency's Risk Assessment Forum, is the first step in a long-term effort to develop cumulative risk assessment guidance for the agency. Not intended as a guide for procedure nor a regulatory requirement, the report is an information document that "identifies the basic elements of the cumulative risk assessment process and provides a flexible structure for conducting and evaluating cumulative risk assessment, and for addressing scientific issues related to cumulative risk." Fact sheet about the report, and the Federal Register notice announcing the report's release."

Abstract: Commercial phosphate (P) fertilizers contain small amounts of heavy-metal contaminants which were minor constituents in phosphate rock (PR). Animal manures and sewage sludges (biosolids) are the main organic fertilizers and the latter also may contain heavy-metal contaminants. Heavy metals in biosolids may be found in the inorganic form or may be organically complexed, which could affect their chemical reactions in soil. These heavy metals may accumulate in soil with repeated fertilizer applications. Cadmium (Cd) is the heavy metal of most concern because it may affect human health. Other heavy metals of possible significance are arsenic (As), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), and vanadium (V). Some countries have set tolerance limits on heavy-metal additions to soil because their long-term effects are unknown. These limits usually are set for the tillage layer (surface 20–30 cm) of soil where most root activity occurs. Controls on heavy-metal concentrations in sewage biosolids and their maximum total and annual loading rates to soil have been imposed in some countries. Regulations also have been proposed for phased-in limits on maximum heavy metal concentrations permitted in P fertilizers, or they are already in effect. Most of the fertilizer regulations relate Cd limits to P concentrations, so P application rates dictate Cd inputs to soil. Regulations affecting sewage biosolids include a number of heavy metals, while those concerning P fertilizers only include limits on Cd at this time.