A Systematic Review of Occupational Exposure to Hydrogen Sulfide in Livestock Operations

ABSTRACT

This systematic review summarizes the current state of knowledge in hydrogen sulfide (H₂S) concentrations within intensive livestock operations. The review was undertaken to better understand H₂S concentrations in intensive livestock operations, in relation to the American Conference of Governmental Industrial Hygienists (ACGIH) limit reduction to a 1 ppm time-weighted average (TWA). Several online academic databases were searched using two conceptual groups of search terms: “livestock” and “hydrogen sulfide.” Industry gray literature was additionally identified via targeted searches of online agriculture-specific Web sites. Title, abstract, and full-text screening were performed to select articles reporting H₂S measurements made within livestock facilities. Forty-five articles were included in this review. The bulk (70%) of articles described swine operations, whereas the remaining represented poultry and dairy operations. Although 14% of the articles described task-based monitoring of H₂S, the majority of articles (86%) involved only area monitoring. Weighted means from all three livestock types were below 1 ppm, although swine operations displayed a wider range of exposure (from 0 to 97 ppm). Despite most mean task-based exposures being close to 1 ppm, the peak concentrations measurements may be higher during power washing (97 ppm) and miscellaneous tasks (11.4 ppm). This review provides a novel overview of H₂S levels in intensive livestock operations, including information on task-based measurements. The review highlights numerous influences that produce a wide variability of H₂S levels in intensive livestock operations. The review also highlights the need for research focused on personal monitoring of daily worker exposures to hydrogen sulfide in intensive livestock operations.

KEYWORDS:

• Hydrogen sulfide
• intensive livestock units
• occupational exposure limit