Assessment of heavy metal and trace element contamination in sachet water and regulatory gaps in Lagos Nigeria

Abstract

A large portion of the Nigerian population lack access to safe drinking water, leading many to depend on sachet water because it is affordable and widely available. This study evaluated heavy metals and trace elements concentrations in sachet water samples from various locations across Lagos State, Nigeria. A cross-sectional study was conducted on 29 sachet water samples from the 20 Local Government Areas of Lagos State. The concentrations of heavy metals and trace elements were measured using the Agilent 5800 Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) system. The samples were clear and debris-free on physical examination, NAFDAC registration numbers, product names, and manufacturing addresses were seen on their labels, however relevant information including batch number, expiry and production dates were not found among the information on the sachet water labels. Chemical analysis of the sachet water showed that the concentrations of lead, arsenic, uranium, and mercury exceeded WHO safety limits in 65.5%, 51.7%, 17.2%, and 3.5% of the samples, respectively. Other heavy metals and trace elements analyzed were within permissible limits. Most of the metals had hazard quotient values below 1, suggesting minimal health risks from these elements for both adult and children's consumers. Sachet water samples in the study area generally meet safety limits for heavy metal and trace element exposure, however, the presence of elevated levels of heavy metals in some samples and poor compliance with the laid down regulations for the sachet water labels calls for strengthened regulatory monitoring.