Metals in honey from bees as a proxy for environmental contamination in the United States

Abstract

This is the first large bio-surveillance study examining the contents and geographic variation of metals of public health concern—arsenic (As), lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), and cobalt (Co)—in honey samples collected across the United States. Metal concentrations were measured using ICP-MS, and the spatial distribution pattern of these contaminants was evaluated using statistical and GIS tools. The mean (highest) values (in μg/kg) were 3.8 (170) for As, 8.0 (451) for Pb, and 0.75 (8.1) for Cd. These values, as well as the mean (highest) concentrations of 29.5 (516) for Ni, 14.3 (166) for Co, and 19.6 (11) for Cr, were markedly lower than global averages reported in other countries. The study identified distinct geographic patterns of honey contamination; particularly high As levels were found in northwestern states, while high Co was measured in the southeast. Health risk calculations based on the hazard quotient (HQ) and hazard index (HI) were below 1 for a daily tablespoon (21g) of honey consumption, indicating no adverse health concerns for children and adults, and all samples fell below the 1.0 × 10−6 threshold for carcinogenic risk from As. The variation in metal concentrations found in samples from different states may reflect the influence of air, water, or soil pollution, as well as differential accumulation across plant species, and the distinct geographic clustering of As and Co warrants further investigation to determine the sources of these metals and to assess public health risks, particularly for As, a well-known carcinogen. In sum, this initial study provides baseline values of metal concentrations in honey that can be useful for monitoring future pollution trends, identifying target areas where reductions of emissions or remediation efforts are most critical, and facilitating discovery in environmental exposures (the exposome) and health research, including on cancer and cardiovascular diseases.