The Fertilizer Institute (TFI) quickly responded last week to the inclusion of fertilizers in a May 6 report by President Barack Obama’s Cancer Panel. The report is titled Reducing Environmental Cancer Risk, What We Can Do Now.
“The Fertilizer Institute is unaware of any scientific information that warrants fertilizers’ mention in this report, when in fact the nutrients found in fertilizers are required by all living organisms,” it said in a statement. “Further, the references to fertilizer in the report released today are contrary to the available body of literature which demonstrates that fertilizers have a positive effect on human health by enhancing the nutritional quality of fruits and vegetables.
“Finally, all major fertilizer products have been proven safe after rigorous human health and ecological toxicity testing,” said TFI. “The results of these tests were successfully submitted by the U.S. Environmental Protection Agency into an international database of chemicals managed by the Organization for Economic Cooperation and Development.”
The 240-page report has a seven-page section entitled “Exposure to Contaminants from Agricultural Sources.” Of the fertilizers, the section hones in on nitrogen and phosphates.
The report says nitrogen may increase cancer risk due to the breakdown of nitrogen by digestive enzymes. Nitrogen would be introduced to humans by way of nitrate that gets into the water system, with groundwater in rural areas being a concern as it would have a greater likelihood of elevated nitrate levels, according to the report. However, the report noted that almost all public water supplies have nitrate levels below the Environmental Protection Agency’s Maximum Contaminant Level (MCL) of 10 mg/L.
While the report cited a study of older women in Iowa that found that those whose drinking water had higher long-term average nitrate levels had an increased risk of bladder and ovarian cancer, it noted that other studies have had mixed results or shown no association with nitrate intake. It said limited mechanistic studies do suggest that nitrate levels below the MCL could be carcinogenic. The report said that further research is warranted, particularly because nitrate levels continue to rise in groundwater as use of nitrogen fertilizer increases. It said with greater production of corn for fuel, nitrate levels in drinking water are likely to continue their upward trend.
The report said phosphate fertilizers are often contaminated with cadmium and are responsible for significant cadmium soil and water contamination. It said fertilized soils have been found to have two-to-six times the cadmium concentration of nearby unfertilized land.
In the food supply, it said cadmium is most highly concentrated in grains and seafood, and residents of southern Louisiana have had pancreatic cancer rates marketedly higher than the national average. It said research has demonstrated an association of rural residence, dietary factors (high consumption of rice, seafood, and pork), and cigarette smoking with higher pancreatic cancer risk, particularly among those with Cajun/Acadian ancestry. It said rice fields in the area are treated with cadmium-containing phosphate fertilizers, which is taken up into the rice, the predominant starch in the Cajun diet. The fields are flooded after the rice harvest, and crawfish, a Cajun staple, are farmed in the previously fertilized fields. The report said urinary cadmium excretion levels in studied Louisiana pancreatic cancer patients have been found to be more than four-fold higher than control subjects.
In addition, the report says phosphate accelerates the leaching for arsenic from the soil into groundwater. It also says phosphate in the soil has been found to increase arsenic accumulation in wheat.
The full study by the President’s Cancer Panel can be found online at http://pcp.cancer.gov.