Black lungs in the general population: a new look at an old dispute
Almost from the time that autopsies were first routinely carried out, darkening of lungs with increasing age was described. Different explanations for the origin of the accumulating black pigment arose and by the early nineteenth century three hypotheses had emerged: 1) soot inhaled into the lungs from the air; 2) carbon accumulating in the lungs from abnormal pulmonary carbon dioxide metabolism; and, 3) pigment derived from the blood.