Chumbo em vegetais folhosos provenientes de sistemas de produção orgânicos e convencionais: revisão sistemática e metanálise

Abstract

Lead (Pb) is one the 10 chemicals of major public health concern listed by World Health Organization, being associated with toxicity in all organs. One reason for Pb occurrence in food are agricultural practices. In this context, organic production systems are highlighted for not using pesticides, which may result in less chemical contamination in food. Considering that, this systematic review (SR) and meta-analysis was conducted aiming to investigate if there are differences in Pb levels in organic (OLV) and conventional leafy vegetables (CLV). This SR and its protocol (PROSPERO CRD42022306048) were based on PRISMA. PECOS was used as a guiding acronym of the present study and of its eligibility criteria, referring to the population (OLV), exposure (Pb levels), comparator (CLV), outcomes (Pb levels in OLV and CLV, and secondary outcomes), and study type (studies reporting primary data). Thus, only analytical, cross-sectional studies which reported data on the analysis of Pb in OLV and CLV were been included. Searches were run on the electronic databases GRICultural OnLine Access (AGRICOLA), CAB Direct, Embase, Food Science and Technology Abstracts (FSTA/EBSCO), GALE Academic OneFile, Google Scholar, International System for Agricultural Science and Technology (AGRIS), Latin American and Caribbean Health Sciences (LILACS), Medline (OVID), ScienceDirect (Elsevier), Scopus, e Web of Science, besides manual searches in articles, directory and archives of thesis and dissertations. No restriction was applied regarding language or publication period. A total of 3,742 registers were imported into the application Rayyan Intelligent Systematic Review. The study selection was conducted by two independent researchers, and conflicting decisions were solved by a third researcher. The risk of bias was assessed with the Joanna Briggs Institute critical appraisal checklist for studies reporting prevalence data, and Revman was the software used for the metaanalyses. GRADE was used for assessing the quality of scientific evidence. After the selection stages, 24 studies were included, of which 22 (91.67%) presented low risk of bias, while two (8.33%) presented medium risk, and none presented high risk. Considering the results reported in dry weight, the mean difference (MD) of the Pb level in the OLV and CLV was not significant (p=0.26), being classified as evidence of ‘low certainty’. Significant difference (p=0.008), was observed in the metanalysis considering results in fresh weight (DM=0.01 mg/kg), indicating an inferior concentration of Pb in OLV, being classified as evidence of ‘moderate certainty’. The most frequent vegetables were lettuce, cabbage, spinach and celery. The most frequent analytical methods were graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS). Four studies (16.67%) presented Pb levels above the maximum limits for at least one sample. From the Public Health point of view, this SR is related to food safety and health surveillance, showing a lower concentration of lead in organic vegetables – an important fact for establishing priorities in the planning and monitoring of food groups, considering the toxicity of contaminants.