CASE REPORTS 277 APLASTIC ANEMIA FOLLOWING EXPOSURE TO PRODUCTS OF THE SULFITE PULP INDUSTRY: A REPORT OF ONE CASE *

T H I S case presents many features of interest. The disease is uncommon and rarely seen by the general practitioner. No report in the literature has been found in which a case of aplastic anemia may have been caused by exposure to products of the sulfite pulp industry. The history revealed that symptoms of intoxication were present for some 17 months prior to seeking medical aid. The patient for some 20 years was manager of a pulp and paper company which makes paper pulp by the Mitscherlich or sulfite process, in which wood chips and calcium bisulfite enter large digesters or autoclaves and emerge finally as sulfite pulp. He was almost daily exposed to fumes at times of high concen-tration in closed areas and was constantly handling and frequently seen chewing pieces of sulfite pulp. Many industrial studies have been made of the toxicological effects of the more commonly used chemicals. Such studies will not of necessity apply di-rectly to the paper industry in which the contaminating chemical substances are not clearly identified and the actual amounts of toxic constituents may be so small as to be estimated with difficulty. Among the possible toxic materials in a sulfite pulp mill are the relief gases from the digester. Investigations of the oil soluble constituents of relief liquor from the pulp mill have revealed some interesting findings. The oil-soluble fraction in relief liquor.represents about 4.5 parts in 12,000, of which about 90 per cent is para cymene. Cymene is a substituted benzene and as such is an irritant. According to Woronow (1929),1 cymene closely resembles pseudo cumene in its effects, and it does not exhibit the tendency, shown by benzene to cause anemia and leukopenia; similar results were reported by Miyamoto (1937).2 Cymene (cymol), methyl isopropyl benzene, can exist in the form of three isomers, of which only the para compound has been studied toxicologically. Other constituents of relief liquor are: sulfur dioxide gas, acetaldehyde, acetone, * Received for publication March 29, 1945