Modification of Major Contributors Responsible for Latrine Malodor on Exposure to Hypochlorous Acid: The Potential for Simultaneously Impacting Odor and Infection Hazards to Encourage Latrine Use

Open defecation remains a common practice in developing countries and leads to high incidence and prevalence of acute gastroenteritis, which is most often caused by human noroviruses (human NoV). Encouraging the use of toilets and pit latrines is one method of improving sanitation; however, it is often hindered by not only cultural traditions but also from a reluctance to use latrines and toilets due to their odor and impression of uncleanliness. In an effort to establish new means to encourage toilet and latrine use, laboratory experiments tested the ability of hypochlorous acid (HOCl) to modify the malodorous compounds identified in the air in latrines in developing countries (indole, p-cresol, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and butyric acid) and inactivate MS2 bacteriophage, a surrogate for human NoV. After 5 minutes, > 94% of indole, p-cresol, DMDS, and DMTS was modified as determined by high-pressure liquid chromatography in the presence of 100 ppm HOCl. A log(10) reduction value (LRV) greater than 6 was seen for MS2 bacteriophage after 5 minutes of exposure to 100 ppm HOCl in solution. Sensory studies indicated that there was a significant difference (P ≤ 0.05) between the untreated and HOCl-treated samples for all five malodorous compounds tested. The findings suggest that introduction of HOCl into the headspace air could encourage latrine and toilet use. Optimization of HOCl dosing in air to accomplish both odor control and reduction of infectious hazards is worthy of further study.