Assessment and Distributions of Phthalates Esters (PAEs) in Groundwater of Gbagi General Market in Ibadan and its Health Risk to the Environment

Abstract

This study assessed the concentrations, spatial distribution, and associated health risks of selected
PAEs in groundwater around Gbagi General Market, Ibadan, Nigeria. A total of 8 groundwater
samples were collected and analyzed using High-performance liquid chromatography (HPLC).
The target PAEs included diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate
(BBP), dimethyl phthalate (DMP), and di-(2-ethylhexyl) phthalate (DEHP). Results showed that
DEHP had the highest mean concentration of 5.73 μg/L, followed by DBP at 2.65 μg/L, BBP at
1.12 μg/L, DEP at 0.07 μg/L, and DMP at 0.03 μg/L. Several samples exceeded the World Health
Organization’s permissible limit for DEHP in drinking water (8 μg/L), with one sample recording
as high as 12.8 μg/L. Spatial analysis revealed contamination hotspots near plastic waste dumps
and drainage channels within the market. The cancer risk assessment revealed that although the
estimated carcinogenic risks (CR) for both adults and children were within the acceptable range
defined by (USEPA) threshold of 1 × 10⁻⁶ to 1 × 10⁻⁴, children exhibited higher lifetime cancer
risks compared to adults. DEHP a known probable human carcinogen, was the dominant
contributor to overall cancer risk, primarily through oral ingestion. This study demonstrates the
significant chemical burden posed by PAEs in urban groundwater, due to improper plastic waste
disposal and intense commercial activity. The result of this findings call for urgent regulatory
intervention, improved market sanitation, and public awareness and provides essential baseline
data for environmental health surveillance and supports development of policies targeting
groundwater safety in Nigeria’s commercial centers.