Has it occurred to you that the food we eat may be poisonous? I’m not talking about salmonella, listeria, campylobacter or E. coli, the bacterial toxins that can contaminate food; I’m talking about fertilizers that may poison our food.

When farmers over-apply fertilizer in the field, they overload veggies with nitrates, and nitrates can be harmful to your health.

Nitrate can do two things: It can harm infants by preventing oxygen from circulating in their blood. Also, nitrate in excess, according to Danish studies, leads to diabetes, which is a worldwide epidemic. So strong is the evidence that excessive nitrate is linked to diabetes that the European Union set a limit on how much nitrate can accumulate in the plant tissues that we eat. Neither California no the United States has set such a food safety limit.

Fertilizer consists mainly of nitrogen, phosphorus and potassium, often represented by the symbol “NPK.” There are two dangers from over-applying it. The first is nitrate accumulation. A number of crops, including beets, celery and spinach, are known to accumulate excess nitrate in their leaves, stems or roots. The second is that rock phosphate fertilizer is often tainted with cadmium. Cadmium has been definitively linked to the formation of breast cancer by Japanese research and the biochemical pathways – at least one of them – are known. Sweden has had a limit on the amount of cadmium in fertilizer for decades.

Nitrates are normally building blocks that make cell walls, chlorophyll and proteins. When faced with drought, beets, celery, spinach and other food plants store nitrates and do not make cellulose, chlorophyll and other complex materials with the nitrates. When we eat the plant, the nitrate passes directly into our blood.

Children and adults have an enzyme in the blood that converts nitrate into nitrite and another pair of enzymes that convert nitrite back into nitrate. Infants lack the reconversion enzyme in their blood, so levels of nitrite spin out of control.

Nitrite reacts with the red-colored, oxygen-carrying substance in the blood called hemoglobin and disables its capacity to carry oxygen to the cells. If there’s no oxygen in your blood, you die.

Children over 6 months and adults have this magic enzyme that reconverts harmful nitrites back into harmless nitrates. Infants exposed to nitrates develop blue baby syndrome. The condition is potentially fatal. Hospitals administer a dye called methylene blue to cure blue babies of the syndrome.

Because of blue baby syndrome, state and federal laws limit the amount of nitrate that can be in drinking water. There is no limit yet for the amount of nitrate that can be found in food.

Interestingly, veterinarians have documented cases where cows have died from eating beet leaves that contain too much nitrate.

Despite the seriousness of nitrate, very few nations have set limits on the amount of nitrate in food. California sets no standard despite the recent advances in science that link nitrate to diabetes and thyroid disorders.

Oddly, the California Department of Food and Agriculture has taken an alternate approach. The problem is over-application of fertilizer, and over-application tends to spoil water as well as food. California’s Water Resources Control Board seeks to protect vulnerable drinking water supplies protected from nitrate intrusions. The approach the two agencies use is called “nitrogen-budgeting,” which is a so-called best management practice, often referred to by bureaucrats as a “BMP.” Even the Calaveras County Code requires farmers to use such practices. Nitrogen-budgeting means that farmers predict their fertilizer needs and apply only what they need to grow a crop and produce a given yield. Using a table of values, they compute how much fertilizer they need to get to that yield. Then they test their field for residual nitrates and they subtract what they already have from their computation, and they are ready to go – using only what nitrate is calculated on paper.

If all the fertilizer applied goes into the crop, then none escapes to contaminate water. Since farmers limit the amount of nitrate to what is needed for a given yield, there is no spare nitrate to accumulate in the plant and poison the food. Every bit of nitrate is used to make the cell walls, green chlorophyll and proteins. None is stored.

But does the new game of regulatory roulette work? The new regulation is fuzzy, if not iffy, in its calculations, which are, at best, educated guesses, and we can’t tell if the BMP really works. Yes, we can test food, but more importantly, we test water. If wells go bad from too much nitrate, we won’t see the nitrate for years, even decades and by then it is too late to reverse the damage to the water supplies. The water board requires farmers to test water for nitrate contamination in order to protect drinking water. But the more immediate danger is nitrate contamination in produce.

The next time you munch a stalk of celery, consider this: celery can’t give you enough digestible calories to stay alive, but it may give you enough nitrate to bring on diabetes. All this creates an interesting dilemma: How can we do green-revolution agriculture in California without poisoning our food?

Bud Hoekstra is an organic farmer in Glencoe. You can reach him at foothillberries@gmail.com.

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