Lead (II) detection and contamination routes in environmental sources, cookware and home-prepared foods from Zimatlán, Oaxaca, Mexico.
An interdisciplinary investigation, involving environmental geochemists, epidemiologists, nurses, and anthropologists, was undertaken to determine the contamination source and pathway of an on-going outbreak of lead poisoning among migrants originating from Zimatlán, Oaxaca, Mexico and living in Seaside, California, and among their US-born children. An initial investigation in Seaside identified grasshopper foodstuff ("chapulines") imported from Mexico and consumed as snacks, as containing alarmingly high lead concentrations (up to 2300 mg/kg). The focus in the present work concentrates on the Oaxacan area of origin of the problem in Mexico, and two potential sources of contamination were investigated: wind-borne dusts from existing mine residues as potential contaminants of soil, plant, and fauna; and food preparation practices using lead-glazed ceramic cookware. Over a three year period, sampling was conducted in Oaxaca using community-level sampling and also targeted sampling with families of cases with lead poisoning in California. In addition to fresh field chapulines, we analyzed for total lead: soil, water, mine residues, and plant materials, both from areas adjacent to or at an abandoned waste site containing mine tailings, and from fields where chapulines are collected; foodstuffs gathered in community markets or in a food transport business; and foodstuffs and cookware gathered from relatives of case families in California. Also, selected new and used lead-glazed clay cookware was extracted for lead, using 0.02 M citric acid and with 4% acetic acid. The results indicated significant presence of lead in mine wastes, in specific foodstuffs, and in glazed cookware, but no extensive soil contamination was identified. In-situ experiments demonstrated that lead incorporation in food is made very efficient through grinding of spices in glazed cookware, with the combination of a harsh mechanical action and the frequent presence of acidic lime juice, but without heating, resulting in high but variable levels of contamination.
Villalobos
M
M
Environmental Bio-Geochemistry Group, LAFQA, Instituto de Geografía, Universidad Nacional Autónoma de México (UNAM), Mexico. mar.villa@stanfordalumni.org
Merino-Sánchez
C
C
Hall
C
C
Grieshop
J
J
Gutiérrez-Ruiz
M E
ME
Handley
M A
MA
D002516:Ceramics / Q000737:chemistry*; D003297:Cooking and Eating Utensils; D004784:Environmental Monitoring; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling; D006801:Humans; D007220:Industrial Waste / Q000032:analysis; D007854:Lead / Q000032:analysis* / Q000737:chemistry; D008800:Mexico; D008906:Mining; D017365:Spices
D007220:Industrial Waste; D007854:Lead