Grand rounds: an outbreak of toxic hepatitis among industrial waste disposal workers

Abstract

Context: Industrial waste (which is composed of various toxic chemicals), changes to the disposal process, and addition of chemicals should all be monitored and controlled carefully in the industrial waste industry to reduce the health hazard to workers.

Case presentation: Five workers in an industrial waste plant developed acute toxic hepatitis, one of whom died after 3 months due to fulminant hepatitis. In the plant, we detected several chemicals with hepatotoxic potential, including pyridine, dimethylformamide, dimethylacetamide, and methylenedianiline. The workers had been working in the high-vapor-generating area of the plant, and the findings of pathologic examination showed typical features of acute toxic hepatitis.

Discussion: Infectious hepatitis and drug-induced hepatitis were excluded by laboratory findings, as well as the clinical course of hepatitis. All cases of toxic hepatitis in this plant developed after the change of the disposal process to thermochemical reaction-type treatment using unslaked lime reacted with industrial wastes. During this chemical reaction, vapor containing several toxic materials was generated. Although we could not confirm the definitive causative chemical, we suspect that these cases of hepatitis were caused by one of the hepatotoxic agents or by a synergistic interaction among several of them.

Relevance to clinical or professional practice: In the industrial waste treatment process, the danger of developing toxic hepatitis should be kept in mind, because any subtle change of the treatment process can generate various toxic materials and threaten the workers' health. A mixture of hepatotoxic chemicals can induce clinical manifestations that are quite different from those predicted by the toxic property of a single agent.

Figure 1

Process of unslaked lime solidification reaction. (A) Reaction is performed in a warehouse with the windows removed. (B) For each reaction, 100–250 drums of liquid wastes and 7–12 tons of unslaked lime are loaded in a constant ratio with liquid wastes. (C) As the wastes and unslaked lime are mixed, thick noxious vapors rise during the heat reaction and escape through the open windows; the full reaction takes > 12 hr with emission of huge amounts of noxious gases and vapors. (D) Final stage of the process after 10 hr of thermochemical reaction.

Figure 2

Clinical course for each case shown by AST level. Seven episodes of acute hepatic injury occurred in five workers from the plant. Case 1’s first episode occurred in May 2001, but the episode was limited only to laboratory findings. Most of the clinical episodes of acute hepatic injury occurred between July and September 2001. The second episodes of cases 1 and 2 developed after they returned to work.

Figure 3

Pathologic findings of toxic hepatitis cases. (A) PAS-stained liver from case 5 showing spotty necrosis of hepatocytes and clumped Kupffer cells containing PAS-positive material (arrows); these find-ings are compatible with the remission stage of acute hepatitis and with toxic hepatitis (magnification, 400×). (B) Hematoxylin and eosin (H&E)–stained liver from case 1 showing portal tracts that are slightly enlarged and infiltrated with inflammatory cells (magnification, 400×). (C) H&E-stained liver from case 5 showing central to portal bridging necrosis (magnification, 200×). (D) Masson trichrome staining of liver from case 4 showing wide periportal necrosis extending into the portal-to-portal area, with regenerative nodules present (magnification, 100×).

Figure 4

Diagram of the industrial waste plant showing the work areas of the hepatitis cases. Case 1 worked in unslaked lime processing. Workplaces of the other cases were northeast from the unslaked lime process warehouse. In this area, the seasonal wind from the southwest is limited to July.