Impact of Climate Variability on Aflatoxin Contamination of Maize Stored in Smallholder Facilities in Kaduna State

Climate variability, manifested through changing temperature and rainfall patterns, is increasingly recognised as a driver of mycotoxin contamination risk in cereals stored across sub-Saharan Africa. In Kaduna State, North West Nigeria, smallholder maize farmers depend on traditional on-farm storage structures that offer limited protection against climate-driven changes in ambient humidity and temperature conducive to Aspergillus growth. This study investigated the impact of climate variability indicators on aflatoxin contamination levels in maize stored in traditional structures across three agricultural zones of Kaduna State over two consecutive post-harvest seasons. Climate data including mean temperature, relative humidity, and rainfall were obtained from the Nigerian Meteorological Agency. Maize samples were collected at monthly intervals from 120 smallholder storage sites. Aflatoxin B1 concentrations were determined by enzyme-linked immunosorbent assay. Grain moisture content, storage duration, and structure type were recorded as covariates. Panel data regression analysis was employed to model the relationship between climate variables and aflatoxin accumulation. Results revealed significant positive associations between relative humidity above 75 percent and aflatoxin B1 concentration (coefficient: 0.42, p less than 0.01). Temperature range variability was a stronger predictor of aflatoxin risk than absolute mean temperature. Thatch-roofed structures showed significantly higher contamination than metallic roof structures. The study provides empirical evidence linking climate variability to aflatoxin dynamics and recommends climate-adaptive storage design and humidity monitoring protocols for smallholder maize farmers in Kaduna State. Keywords: aflatoxin, climate variability, maize storage, smallholder, Kaduna.