A man works in casting of non-ferrous metals and alloys for 12 years. In the air of working area there was registered high content of heavy metals, carbonmonoxide, and nitrogen. During periodic health examination the patient presents with as the no vegetative syndrome, sharp abdominal pains, constipations, pain in the hepatic area. In the laboratory analysis of urine: aminolevulinic acid and coproporphyrin are detected. In the laboratory analysis of blood: reticulocytosis, low hemoglobin level. Such intoxication is caused by: