A Market Basket Survey of Horticultural Fruits for Arsenic and Trace Metal Contamination in Southeast Nigeria and Potential Health Risk Implications

Abstract

Background. Elevated arsenic and trace metal contamination of the terrestrial food chain represents one of the most significant environmental risk exposures for human populations in developing countries. Metalloid and metal contamination in horticultural crop produce such as fruit is a public health concern in Nigeria. Local fruits are cheap sources of vitamins and minerals for the resident population and pose an important dietary threat of metal(loid) toxicity through consumption. Objectives. Market basket investigation of five locally grown (guava, pineapple, orange, and pawpaw) and imported (apple) fruits was conducted to measure the total concentrations of arsenic (As), mercury (Hg), copper (Cu), and lead (Pb) present in these fruits from southeastern Nigeria (Awka, Anambra). Methods. Fruits were analyzed for As and the three metals using atomic absorption spectrophotometry. Moisture content of fruits was determined and used to transform metal concentrations in dry weight to wet weight and compared to Codex food grade standards and assorted (sub)tropical fruits, edible and inedible peels. Results. The mean ± standard deviation of elemental concentrations in dry weight ranged from 20.0±0.71–96.84±0.00 µg g-1 for As, 0.02±0.02 – 0.89±0.33 µg g-1 for Hg, 0.11±0.01 - 0.18±0.40 µg g-1 for Cu, and <0.001 – 0.03±0.05 µg g-1 for Pb. The As concentrations (wet weight) in fruits were ~32–166 orders of magnitude higher than Codex Alimentarius Commission (Codex) maximum As food grade levels. Guava and apple methyl Hg concentrations were ~6–~1 orders of magnitude higher than Codex maximum levels, while the content of Cu and Pb in fruits were within acceptable standard limits. Conclusions. The significant concentrations of As and Hg in the examined fruits indicate a potential public health threat. Efforts are needed to initiate and sustain continued monitoring of trace elements in fruits and food sold to consumers due to variation in contaminating sources to ensure food safety. Although a great deal of information exists on Hg toxicity, research on metalloids such as As remains limited in Nigeria and no reliable guidelines exist. Further research is recommended to determine the ecotoxicity of As in Nigeria. Competing Interests. The authors declare no competing financial interests.