Chronic exposure to ambient levels of urban particles affects mouse lung development.
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.
Mauad
Thais
T
Department of Pathology, Sao Paulo University Medical School, São Paulo, SP, Brazil. tmauad@usp.br
Rivero
Dolores Helena Rodriguez Ferreira
DH
de Oliveira
Regiani Carvalho
RC
Lichtenfels
Ana Julia de Faria Coimbra
AJ
Guimarães
Eliane Tigre
ET
de Andre
Paulo Afonso
PA
Kasahara
David Itiro
DI
Bueno
Heloisa Maria de Siqueira
HM
Saldiva
Paulo Hilário Nascimento
PH
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
D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions