Exposure estimation to Glyphosate through the consumption of Lebanese bread

Abstract

Background and objective: Glyphosate, a nonselective herbicide widely-used in crop production, persists in food products leading to residues. Research findings on the health effects of glyphosate are highly controversial due to a perceived conflict of interest by the majority of research funders who are glyphosate manufacturers themselves. Glyphosate residues are detected in various tested food products globally, but data about exposure in Lebanon is lacking. Bread is a stable food in the Lebanese diet and the extend of its contamination with glyphosate is unknown. This study aimed at determining the concentration of glyphosate in the majority of bread products sold in Mount Lebanon and at estimating exposure to glyphosate through the consumption of bread. Methods: Enzyme linked immunosorbent assay (ELISA) method was utilized to quantify glyphosate residues in 100% of Lebanese bread sold in Mount Lebanon (n=80) including white, brown, bran, whole wheat and unconventional (almond, quinoa, woodbees, healthy fiber, extra fiber, high protein, oat) types as all bakeries in Mount Lebanon were visited. Glyphosate levels where compared to maximum residue levels (MRL) of 30 mg/kg as listed by Codex in addition to MRLs of 30, 10, and 5 mg/kg for wheat and 15 mg/kg for bran as listed in the United States, Europe, and Canada, respectively. Exposure assessment of Lebanese population to glyphosate through bread consumption was also estimated. Findings: The percentage of positive samples was 72.7, 69.2, 85.7, 78.9 and 100%, respectively for white, brown, bran, whole wheat, and unconventional bread with a median glyphosate level of 14.9, 18.7, 28.5, 25.7 and 52.9 ppb, respectively. White bread had significantly lower levels as compared to other bread types (P=0.004). Glyphosate levels in all products were below the MRL. The Estimated daily intake (EDI) of glyphosate through bread consumption in Lebanon was estimated at 0.0702 μg/kg BW/day which is only 0.000117% of the Acceptable Daily Intake (ADI) of 1 mg/kg/day as listed by Codex, and 0.00039% of the ADI of 0.5 mg/kg/day as listed by the German Federal Institute for Risk Assessment. Conclusion: Despite more than two-thirds of samples containing glyphosate, levels fall below MRL, and Lebanese consumers do not seem to be exposed to unacceptable amounts of this herbicide through bread. Future studies need to investigate glyphosate contamination in other staple foods, and a more accurate assessment of exposure at the population level needs to be investigated.