According to the latest news from San Francisco, 20 tons of free bags labeled "organic biosolid compost" actually contained sewage sludge from nine California counties. Sewage sludge is the end product of the treatment process for any human waste, hospital waste, industrial waste and storm water that goes down the drain. That highly concentrated toxic sludge contains anything that went down the drain but did not break down during the treatment process. This typically includes a number of heavy metals, polycyclic aromatic hydrocarbons, pharmaceuticals, steroids, flame-retardants, bacteria (including antibiotic-resistant bacteria), fungi, parasites, and viruses.
Compost is a common name for humus, which is the result of the decomposition of organic matter. The most effective decomposers are bacteria and other microorganisms. Some of them are not harmful for human body, plants and animals; some of them can cause disease and are called "pathogenic". Bacteria are responsible for most food spoilage. Also important are fungi, molds, protozoa, and actinomycetes – which is something between a fungus and a mold and is often seen as white filaments in decomposing organic matter. These species occur in soil and generally known as low-oxygen – utilizing bacteria. Yeasts, mildews, rusts, mushrooms, and truffles are examples of fungi. Some of them are harmless to animals and higher plants; others are dangerous disease-causing agents.
Toxins in organic compost are natural products of living cells. They can not be avoided. It's not in a human power. We are protected from disease by our immune system. And nature takes it's slow course, producing everything what plants needed according to environment and external conditions. At a macroscopic level, earthworms, ants, snails, slugs, millipedes, sow bugs, spring-tails, and others work on consuming and breaking down the organic matter. When the natural composting process occurs, all components of the system work together and cooperate. By adding some ingredients and conditions to this natural system humans interrupt the balance. It causes the confinement of toxic byproducts, which we call toxicants. By contributing some toxic ingredients into composting process we multiply poisonous substances to the unknown extend.
We should be very conscious about such kind of experiments, as nature always gives us the best lesson.