Fungicides are any chemical compounds, naturally occurring or synthesized, or biological organisms that are used to kill or prevent or inhibit the growth of fungi and fungal spores. Fungi include yeast, molds, and mushroom. These organisms can damage crops, infect livestock, and produce toxic compounds. Because of this risk to agriculture, a great number of fungicides exist to combat the huge diversity of fungi foes. TellSpec today will be examining three: Triclosan, Vinclozolin, and Thiabendazole. These cumbersome words describe potentially dangerous compounds.
Triclosan (TCS) is perhaps the most innocent of our three, at first glance, and its problematic nature is not immediately apparent. It is a halogenated phenol, or organochlorine, compound that is not highly regulated but is widely used. It is an antimicrobial though it has, of course, antifungal properties, that is found across North America, Europe, and Asia in everything from disinfectants and detergents to toothpaste, mouthwash, and deodorant. Evidently, though it is used in agriculture, residue on food is perhaps not the most likely source of consumption. Triclosan is indeed approved for use that leads to human consumption, and has been described as not likely to cause any adverse health effects in children or adults who use products as intended. This, however, is where the issue appears to lie, as TCS is not only intentionally part of a variety of products but is also a compound that makes its way into wastewater and the water treatment system in significant quantities. This has raised concerns of negative ecological effects on certain fish and is believed to contribute to antibiotic resistance. Furthermore, this source can lead to exposure to TCS above the levels studied when establishing its safety. Additionally, TCS has been found in human plasma and breast milk and has been implicated as an endocrine disruptor. All of these are concerns that were not part of the original evidence for safety and widespread use, which has pushed its re-review date by the FDA up by ten years.
Vinclozolin is a less widespread foe. In the US its use is approved only for canola crops and residual levels are permitted only in canola, livestock that have been fed canola, and wine grapes. However, vinclozolin has historically been used in the US to treat berries, lettuce, and wine grapes; different countries have different regulations against it; and a significant amount of North American produce is imported and residues may persist. Vinclozolin and its metabolites can have carcinogenic and antiandrogenic effects, where androgens are the male steroid hormones such as testosterone. This can affect development and function of sex organs and hormone systems, fertility, as well as circulating levels of sex hormones. In studies of mice, vinclozolin was able to bind to receptors, leading to masculinization of females and feminization of males. Furthermore vinclozolin shows transgenerational effects: the offspring of mothers exposed to vinclozolin can show physical damage (aside from poor organ development) and behavioural abnormalities.
Finally thiabendazole. Thiabendazole is approved for use in a variety of crops in a variety of methods: as a pre-planting treatment for soybean, wheat, and sweet potatoes; on growing mushrooms; and as a post-harvest dip or spray for citrus, apples, pears, bananas, mangos, papaya, plantain, carrots, avocados, peas, and potatoes. This spray is typically applied at the same time as wax coating of the produce occurs. It is approved in the US but not in the EU, Australia, or New Zealand. In animal studies, thiabendazole is carcinogenic and damaging to normal liver and thyroid function. Thiabendazole is assessed as safe to humans at the levels expected from a typical diet (and residue levels are, as a standard, restricted to levels well below those which cause negative effects in studies). However thiabendazole may be present not only in the aforementioned crops but also flour, rice, meat, meat byproducts, milk, poultry, and eggs.
So what is there to do? Fungicide residues are extremely difficult to avoid, as they can persist in soil and water. Organic produce and crops do not permit use of synthetic fungicides, and so are a good place to start. Shopping at local Farmers’ Markets offers the chance to ask the grower how they raise their crops and livestock. Choosing unwaxed produce and peeling fruits and vegetables can avoid some residues. Beyond that, staying informed and advocating, as is your right as a consumer, for greater safety evaluation and regulation of these compounds’ presence in your food.