The second group is uncharacteristic of food products and enters them from the outside — chemicals that are added to food during production, such as preservatives, and chemical or biological pollutants unrelated to the cooking process.
Substances entering from outside are the most dangerous group. They in turn are divided into biological toxins: bacterial, botulinum, mycotoxins, spores of unicellular and multicellular organisms, algae.
Chemical toxins are mercury, chromium, lead, arsenic, cobalt, cadmium, nickel, tin, pesticides, nitrites, nitrates, polycyclic compounds, growth stimulants used in agricultural industry, radioisotopes — strontium 90, caesium 137.
The most dangerous harmful substances are heavy metal salts, pesticides and metabolism products, radionuclides, nitrates, nitrites and polycyclic aromatic hydrocarbons.
Harmful substances in the air are numerous compounds of vapors and gases of benzene, toluene, sulfur anhydride, hydrocarbon monoxide, lead aerosols, toxic dust that is formed when processing of metals.
Negative effects of harmful substances on the human body can lead to cancer diseases, failures in the immune system, genetic disorders, severe allergic reactions, $ disruptions to all vital bodies.$ With severe poisoning, a lethal outcome can occur.