title: Distribution of lead in human milk fractions: relationship with essential minerals and maternal blood lead.
abstract: The purpose of this study was to determine the concentration and distribution of lead, calcium, iron, zinc, and copper in major fractions (fat, casein, whey) of mature milk from 38 nursing adult women with low environmental lead exposure. The potential associations between milk lead and maternal blood lead and between milk and blood lead and essential mineral data (nutritional status, dietary intake, and milk concentration) were investigated. Maternal blood lead (geometric mean, 60 microg/L) was negatively associated, although modestly, with dietary calcium intake (r=-0.32, p=0.02). Lead in whole milk (geometric mean, 1.2 microg/L) was positively associated with calcium in whole milk (r=0.56, p=0.005). Distribution of lead in milk fractions was 63%, 28%, and 9%, in whey, fat, and casein, respectively. Milk distribution of essential minerals was 67-76%, 17-18%, and 7-17% in whey, fat, and casein, respectively. Lead in milk whey was positively associated with lead in maternal blood (r=0.49, p=0.02). However, milk lead was not affected by nutritional status, dietary intake, and milk composition of the essential minerals. The high percentage of lead in the milk whey fraction, as seen for the essential minerals, suggests that most lead in human milk is bioavailable to the infant.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, CT, Bloco A, 528, 21949-900 Rio de Janeiro, Brazil.
authors.forename: Alexandra da Silva
authors.initials: Ada S
authors.lastname: Anastácio
authors.forename: Carmem Lucia Porto
authors.initials: CL
authors.lastname: da Silveira
authors.forename: Norbert
authors.initials: N
authors.lastname: Miekeley
authors.forename: Carmen Marino
authors.initials: CM
authors.lastname: Donangelo
mesh_terms: D000328:Adult; D001682:Biological Availability; D001938:Brazil; D002118:Calcium / Q000032:analysis; D002136:Calcium, Dietary / Q000008:administration & dosage; D002364:Caseins / Q000032:analysis; D003300:Copper / Q000032:analysis; D005260:Female; D006017:Glycolipids / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007501:Iron / Q000032:analysis; D007774:Lactation; D007854:Lead / Q000032:analysis* / Q000097:blood; D066292:Lipid Droplets; D008894:Milk Proteins / Q000032:analysis; D008895:Milk, Human / Q000737:chemistry*; D009752:Nutritional Status; D000067816:Whey Proteins; D015032:Zinc / Q000032:analysis
chemical_list: D002136:Calcium, Dietary; D002364:Caseins; D006017:Glycolipids; D006023:Glycoproteins; D008894:Milk Proteins; D000067816:Whey Proteins; C110367:milk fat globule; D007854:Lead; D003300:Copper; D007501:Iron; D015032:Zinc; D002118:Calcium