Impact of exposure to sunlight before consumption of packaged potable water (Sachet Water) in Calabar Metropolis, Cross River State, Southeastern Nigeria

Background Potable water have been shown to be a source of contamination due to poor handling during its supply chain process. It is common practice for sachet water, a widely consumed potable water across Nigerian and West African cities to be exposed to sunlight for hours daily before they are sold to consumers. This practice coupled with the polyethene plastic packaging could cause leaching of heavy metals and other chemical components of the plastic package into the sachet water, and also cause its biological quality to deteriorate posing great public health concerns which prompted this study. Methods Three (3) sachet water brands (n = 4 per brand) were collected and exposed to sunlight daily for 14, 28, and 48 days were analyzed for heavy metals, total hardness, and other physico-chemical parameters using standard protocols. In addition, we also evaluated total heterotrophic bacteria and coliform counts, and antibiotic susceptibility of resulting isolates. Results All brands of the exposed sachet water recorded increased levels of physico-chemical parameters (except pH) and heavy metals compared to the control group in a linear fashion to exposure time. Zn was the most ingested from sachet water brands. The ADD, HQ, and HI evaluations revealed that consuming these brands of sachet water exposed to different durations of sunlight could be expose consumers to Cr, Cd, Pb, As, and Ni toxicities. The CR of Cr, As, and Ni in all brands of the sachet water exposed to sunlight were above the safe value of 10− 4, indicating a likelihood of the population having cancer after over 60 years of exposure. Ni posed the highest carcinogenic risk in all sachet water brands exposed to sunlight for 42 days. All the brands evaluated failed to meet the World Health Organization and national safety limits for total heterotrophic bacteria and total coliform counts. Six out nine isolates elaborated extracellular amylase while all produced protease, enzymes linked with biofilm formation and pathogenicity, respectively. Furthermore, the isolates showed multi-drug resistance. Conclusion The potential health risk inherent in this practice has significant public health implications for the consumers across Nigeria and the West African region.