Protocol for a systematic review and meta-analysis of human exposure to pesticide residues in honey and other bees’ products

Background: The presence of pesticides in honey and related products is an increasing concern for consumers and producers, although there is lack of data on the current burden of exposure of the general human population through these products. We present a protocol for a systematic review and meta-analysis of contamination to insecticides, herbicides and fungicides of products from honeybees, and an estimation of how much the consumption of these products contributes to the ADI (Acceptable Daily Intake) of selected substances. Objectives: We aim to systematically review and meta-analyse studies on the contamination to plant protection products in honey, royal jelly, beeswax and propolis, applying the Navigation Guide and WHO-ILO systematic review methodology as an organizing framework. Data sources: We will search electronic academic databases for potentially relevant records from PubMed, TOXNET and EMBASE. We will include quantitative studies analysing the contamination from insecticides, herbicides and fungicides in honey, propolis, royal jelly and beeswax. In particular, we will evaluate the presence of the following substances and classes of pesticides: Glyphosate, Chlorpyrifos, pyrethroid and neonicotinoid pesticides, fungicides and acaricides. Study appraisal and synthesis methods: At least two authors will independently screen titles and abstracts at a first stage of review, and full texts at a second stage, of potentially eligible records against the eligibility criteria; data extraction of included studies will then be performed by at least two authors, in blind. At least two authors will assess risk of bias and the quality of evidence, using the most suited tools currently available. The data on prevalence of contaminated samples and concentration of pesticides in the products will be combined using meta-analysis: when more than three studies reporting the necessary measures to fit the models are available, meta-analysis will be performed separately by product and by exposure; otherwise, weighted descriptive analysis will be performed. We will report the results using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA).