Grand Rounds: An Outbreak of Toxic Hepatitis among Industrial Waste Disposal Workers

Article excerpt

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.

KEY WORDS: complex exposure, dimethylacetamide, hepatotoxicity, industrial waste, liver biopsy, toxic hepatitis. Environ Health Perspect 115:107-112 (2007). doi:10.1289/ehp.8951 available via http://dx.doi.org/ [Online 18 September 2006]

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Case Presentation

From May to September 2001, two women and three men working in an industrial waste treatment plant in Ulsan, Korea, developed acute hepatitis.

To more efficiently treat a larger quantity of waste, in May 2000 the plant introduced a new process solidifying liquid wastes through thermochemical reaction evoked by unslaked lime, thereby evaporating volatiles. During this process, workers put 100-250 drums (200 L) of liquid wastes and 7-12 tons of unslaked lime into a vat of 10 m x 25 m x 1 m. The thermochemical reaction started within 20 min, after which the workers stirred the mixture a few times with an excavator (Figure 1).

The reaction continued for at least 12 hr, becoming more explosive over time; it generated high temperature and intermittent firing, and profusely spread malodorous vapors. The warehouse had wide entrances on both sides, and all the window glass on the external wall had been removed, allowing the volatiles to spread throughout the factory (Figure 1). From May until November 2001, this process was carried out > 10 times each month. On 18 September 2001, we sampled the waste oils and solvents from the unslaked lime process and analyzed them by gas chromatographymass selective detector (HP 5973 Series, Hewlett Packard, Wellesley, MA, USA). Because the process had been discontinued after the hepatitis outbreaks, we simulated this process on a smaller scale in the same building where this process had been conducted. Several chemicals, including dimethylformamide (DMF), dimethylacetamide (DMAc), and pyridine, were detected in some of the samples collected from a walk-through before and after the simulated process (Table 1).

Clinical course of the cases. Case 1, a 51-year-old male, had been employed in the plant since 1986 and moved to the unslaked lime process with two other co-workers in July 2000. …