title: Chronic exposure to ambient levels of urban particles affects mouse lung development.
abstract: BACKGROUND
  Chronic exposure to air pollution has been associated with adverse effects on children's lung growth.
  
  
  OBJECTIVE
  We analyzed the effects of chronic exposure to urban levels of particulate matter (PM) on selected phases of mouse lung development.
  
  
  METHODS
  The exposure occurred in two open-top chambers (filtered and nonfiltered) placed 20 m from a street with heavy traffic in São Paulo, 24 hours/day for 8 months. There was a significant reduction of the levels of PM(2.5) inside the filtered chamber (filtered = 2.9 +/- 3.0 microg/m(3), nonfiltered = 16.8 +/- 8.3 microg/m(3); P = 0.001). At this exposure site, vehicular sources are the major components of PM(2.5) (PM <or= 2.5 microm). Exposure of the parental generation in the two chambers occurred from the 10th to the 120th days of life. After mating and birth of offspring, a crossover of mothers and pups occurred within the chambers, resulting in four groups of pups: nonexposed, prenatal, postnatal, and pre+postnatal. Offspring were killed at the age of 15 (n = 42) and 90 (n = 35) days; lungs were analyzed by morphometry for surface to volume ratio (as an estimator of alveolization). Pressure-volume curves were performed in the older groups, using a 20-ml plethysmograph.
  
  
  RESULTS
  Mice exposed to PM(2.5) pre+postnatally presented a smaller surface to volume ratio when compared with nonexposed animals (P = 0.036). The pre+postnatal group presented reduced inspiratory and expiratory volumes at higher levels of transpulmonary pressure (P = 0.001). There were no differences among prenatal and postnatal exposure and nonexposed animals.
  
  
  CONCLUSIONS
  Our data provide anatomical and functional support to the concept that chronic exposure to urban PM affects lung growth.
authors.affiliation: Department of Pathology, Sao Paulo University Medical School, São Paulo, SP, Brazil. tmauad@usp.br
authors.forename: Thais
authors.initials: T
authors.lastname: Mauad
authors.forename: Dolores Helena Rodriguez Ferreira
authors.initials: DH
authors.lastname: Rivero
authors.forename: Regiani Carvalho
authors.initials: RC
authors.lastname: de Oliveira
authors.forename: Ana Julia de Faria Coimbra
authors.initials: AJ
authors.lastname: Lichtenfels
authors.forename: Eliane Tigre
authors.initials: ET
authors.lastname: Guimarães
authors.forename: Paulo Afonso
authors.initials: PA
authors.lastname: de Andre
authors.forename: David Itiro
authors.initials: DI
authors.lastname: Kasahara
authors.forename: Heloisa Maria de Siqueira
authors.initials: HM
authors.lastname: Bueno
authors.forename: Paulo Hilário Nascimento
authors.initials: PH
authors.lastname: Saldiva
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects*; D000818:Animals; D001938:Brazil; D004195:Disease Models, Animal; D005260:Female; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D051379:Mice; D052638:Particulate Matter / Q000009:adverse effects*; D011650:Pulmonary Alveoli / Q000254:growth & development / Q000473:pathology; D012129:Respiratory Function Tests; D014505:Urban Population; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions