title: Mercury, lead and cadmium in human milk in relation to diet, lifestyle habits and sociodemographic variables in Madrid (Spain).
abstract: BACKGROUND
  Although breastfeeding is the ideal way of nurturing infants, it can be a source of exposure to toxicants. This study reports the concentration of Hg, Pb and Cd in breast milk from a sample of women drawn from the general population of the Madrid Region, and explores the association between metal levels and socio-demographic factors, lifestyle habits, diet and environmental exposures, including tobacco smoke, exposure at home and occupational exposures.
  
  
  METHODS
  Breast milk was obtained from 100 women (20 mL) at around the third week postpartum. Pb, Cd and Hg levels were determined using Atomic Absorption Spectrometry. Metal levels were log-transformed due to non-normal distribution. Their association with the variables collected by questionnaire was assessed using linear regression models. Separate models were fitted for Hg, Pb and Cd, using univariate linear regression in a first step. Secondly, multivariate linear regression models were adjusted introducing potential confounders specific for each metal. Finally, a test for trend was performed in order to evaluate possible dose-response relationships between metal levels and changes in variables categories.
  
  
  RESULTS
  Geometric mean Hg, Pb and Cd content in milk were 0.53 μg L(-1), 15.56 μg L(-1), and 1.31 μg L(-1), respectively. Decreases in Hg levels in older women and in those with a previous history of pregnancies and lactations suggested clearance of this metal over lifetime, though differences were not statistically significant, probably due to limited sample size. Lead concentrations increased with greater exposure to motor vehicle traffic and higher potato consumption. Increased Cd levels were associated with type of lactation and tended to increase with tobacco smoking.
  
  
  CONCLUSIONS
  Surveillance for the presence of heavy metals in human milk is needed. Smoking and dietary habits are the main factors linked to heavy metal levels in breast milk. Our results reinforce the need to strengthen national food safety programs and to further promote avoidance of unhealthy behaviors such as smoking during pregnancy.
authors.affiliation: Environmental and Cancer Epidemiology Unit, National Center for Epidemiology, Carlos III Institute of Health (ISCIII), Madrid, Spain. egarciag@isciii.es
authors.forename: Esther
authors.initials: E
authors.lastname: García-Esquinas
authors.forename: Beatriz
authors.initials: B
authors.lastname: Pérez-Gómez
authors.forename: Mario Antonio
authors.initials: MA
authors.lastname: Fernández
authors.forename: Ana María
authors.initials: AM
authors.lastname: Pérez-Meixeira
authors.forename: Elisa
authors.initials: E
authors.lastname: Gil
authors.forename: Concha
authors.initials: C
authors.lastname: de Paz
authors.forename: Andrés
authors.initials: A
authors.lastname: Iriso
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Sanz
authors.forename: Jenaro
authors.initials: J
authors.lastname: Astray
authors.forename: Margot
authors.initials: M
authors.lastname: Cisneros
authors.forename: Amparo
authors.initials: A
authors.lastname: de Santos
authors.forename: Angel
authors.initials: A
authors.lastname: Asensio
authors.forename: José Miguel
authors.initials: JM
authors.lastname: García-Sagredo
authors.forename: José Frutos
authors.initials: JF
authors.lastname: García
authors.forename: Jesus
authors.initials: J
authors.lastname: Vioque
authors.forename: Marina
authors.initials: M
authors.lastname: Pollán
authors.forename: Gonzalo
authors.initials: G
authors.lastname: López-Abente
authors.forename: Maria José
authors.initials: MJ
authors.lastname: González
authors.forename: Mercedes
authors.initials: M
authors.lastname: Martínez
authors.forename: Pedro Arias
authors.initials: PA
authors.lastname: Bohigas
authors.forename: Roberto
authors.initials: R
authors.lastname: Pastor
authors.forename: Nuria
authors.initials: N
authors.lastname: Aragonés
mesh_terms: D002104:Cadmium / Q000032:analysis*; D004781:Environmental Exposure; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007854:Lead / Q000032:analysis*; D008019:Life Style; D008628:Mercury / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis; D008895:Milk, Human / Q000737:chemistry*; D016273:Occupational Exposure; D011247:Pregnancy; D012959:Socioeconomic Factors; D013030:Spain; D014028:Tobacco Smoke Pollution; D055815:Young Adult
chemical_list: D019216:Metals, Heavy; D014028:Tobacco Smoke Pollution; D002104:Cadmium; D007854:Lead; D008628:Mercury