Calcium arsenate was also frequently used as a pesticide on a wide range of agriculture crops, including asparagus, beans, blackberries, blueberries, boysenberries, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, collards, corn, cucumbers, dewberries, eggplant, kale, kohlrabi, loganberries, melons, peppers, pumpkins, raspberries, rutabagas, spinach, and squash—until the EPA canceled registration for its use in 1988. The registration was canceled after it was found that these pesticides posed “cancer risks to workers and acute toxicity to the general public.”37
Not only were edible crops treated with calcium arsenate, but cotton crops spanning millions of acres in states including Texas and Oklahoma were annually sprayed with arsenic acid, leaving soils contaminated at levels that measured as high as 830 ppm.38
According to the EPA, many farmers who had been interviewed claimed their orchard trees lived shorter lives and that their fields were unsuitable for various forage crops typically grown during alternating years, giving support to the case for the negative effects presented by widespread arsenic soil contamination. The heaviest scheduled uses were in repelling Syneta beetles in apricots, peaches, and quince. Five to six pounds of arsenic-laced pesticide were used per 100 gallons of water, a mixture used on these crops for decades. Grapes were also subjected to some of the heaviest doses of arsenic, with sodium arsenate fungicide registered for use at an average rate of 3 to 9 pounds per acre in an effort to stop black measles and crown gall.
While arsenic pesticides have been found to metabolize into secondary forms with the aid of microorganisms, researchers have discovered that about 20 percent of the toxins remained in the soil in their original form decades later, even on fields that received only a single topical soil application. Researchers also found that 55 percent of croplands sprayed with pesticides containing arsenic trioxide back in the 1950s were irreversibly leaching into both groundwater and soils over time.39
Thus, repeated and widespread applications of lead arsenate and other pesticides have contributed to significant accumulations of lead and arsenic in soils, and these toxins can still be found even decades after their use declined or was banned, with horrible health implications that continue to this day.40
Ken Rudo, who has worked as the state toxicologist for North Carolina’s Division of Public Health for more than twenty-four years, confirmed that arsenic compounds bind tightly to the soil, presenting a multitude of potential issues. “These chemicals have just tremendously long half-lives in the ground,” Rudo stated in an EPA report.41 The extensive spread of lead arsenate has made remediation of soils difficult, particularly as arsenic moves to the subsoil layers much more quickly and pervasively than other metals such as lead.
Soil analysis studies in the arsenic- and lead-tainted orchards of Massachusetts have revealed that the two metals “Pb and As bind ‘tightly’ to soil HA [humic acids] molar mass fractions.”42
A study in Taiwan found an important relationship between the geographical concentrations of leading heavy metals, including arsenic and nickel, and the prevalence of oral cancer in patients who smoked or chewed betel quid (a combination of betel leaf, areca nut, and slaked lime). That is, cancer and other malignancies predominated in areas where the soil was contaminated with those elements.43
TOXIC ELEMENTS IN FERTILIZERS
The prevalence of heavy metal compounds in most fertilizers used in agriculture today poses ongoing problems for the bioaccumulation of toxins in crops, animals, humans, and the rest of the food chain.1
Naturally occurring elements and heavy metals (including mercury, lead, cadmium, and arsenic) are frequently found in combination with some of the world’s leading industrial ores. This means that mining and processing those ores brings to the surface of the planet toxic elements that would have otherwise stayed buried.
Such is the case with phosphorous, which, alongside nitrogen and potassium, is one of the most important macronutrient constituents used in the creation of fertilizers. Phosphate ore typically contains cadmium in concentrations as high as 300 mg/kg, with sedimentary rock containing the highest concentrations. Other hazardous metals such as lead, nickel, and copper are also abundant in phosphate ores.2,3
As the primary application of phosphate ore is in the creation of fertilizers, its contamination by cadmium means a significant amount is added to the soil, creating abundant opportunities for human exposure to the known carcinogen and environmental toxin, especially through dietary uptake of foods and the inhalation of tobacco smoke.4
However, while phosphate fertilizers contribute a significant quantity of metals—particularly cadmium—to the soil, it is not the number one contributor. It may surprise many to know that industrial waste and sewage sludge is also exploited as a source of fertilizer, and contributes vastly higher quantities of heavy metals and other toxins to soils, and ultimately human intake, than nonwaste fertilizers ever could.5
EPA Okays Selling of Sewage Sludge
The wet, solid cake that remains after wastewater treatment plants process industrial and residential waste has long been referred to as sewage sludge. Decades ago, it was common practice for many municipalities—particularly very large urban areas—to haul the sludge and dump it into oceans and waterways, until the practice was banned by the EPA in 1992.6
In the mid-1990s, two lobbying groups—the U.S. Composting Council (USCC) and the Water Environment Federation (WEF)—joined forces with the EPA to promote the use of sewage sludge as a safe, effective, and cheap fertilizer under the rebranded name “biosolids.” It was actively promoted by many agencies as an effective way to dispose of human waste, while creating a viable by-product market.7
In 1997, the EPA said their “longstanding policy encourages the beneficial reuse and recycling of industrial wastes, including hazardous wastes, when such wastes can be used as safe and effective substitutes for virgin raw materials.”8
A study on the bioavailability of cadmium and its accumulation in soils found that while continued phosphate fertilization raised cadmium levels, the increase was much lower than those observed from the application of sewage sludge as fertilizer, both in overall accumulation as well as in bioavailability to Swiss chard and other plants.9
Heavy metals in biosolids can be a particularly worrisome issue, as the toxic elements frequently found in drinking water, food, and medicine tend to concentrate in the biosolids that are routinely applied to soils as fertilizer. There, they accumulate in the soil, leading to a persistent rise in toxic elements taken up by food crops.
Biosolids from sewage waste can contain especially high levels of accumulated metals—from lead, to cadmium, to mercury, to arsenic, or others such as nickel, copper, aluminum, or tin.10
In February of 2016, I acquired a bag of “Dillo Dirt” from the city of Austin, Texas, and I tested it for heavy metals via ICP-MS instrumentation. Dillo Dirt is composted human sewage that’s purchased by landscapers and home gardeners for use on lawns and gardens. Even though the bag says, in small print, that it’s not sold for use on edible vegetable gardens, it is positioned on retail shelves as a garden compost product (and no one reads the small print on a bag of compost anyway).
As you might expect, my ICP-MS analysis showed that Dillo Dirt was heavily contaminated with every toxic element tested, including lead, mercury, cadmium, arsenic, and copper. An organic chemistry analysis conducted by my colleague via LC/MS also revealed shockingly high levels of a chemical fungicide in the compost product.
Mercury used in dental amalgams poses a particularly significant source of concentrated metal exposure and environmental pollution through biosolids, as most dental practices have, for decades, used municipal water for waste disposal, and have been recognized as a significant contamination source.11,12