A worker at a workshop that produces car batteries came to a doctor with complaints of nausea, loss of appetite, sharp pain in the abdominal cavity, and constipations. Examination reveals elevated blood pressure, bradycardia, an enlarged liver, pain in the right subcostal region, a grayish blue stripe on the gums, and gray skin. Complete blood count indicates the presence of erythrocytes with basophilic stippling and reduced hemoglobin levels. Aminolevulinic acid and coproporphyrin can be detected in the patient's urine. What is the most likely provisional diagnosis in this case?