A study of farm worker children in the Salinas Valley has suggested that chronic exposure to pesticides can harm the lung function of children by nearly as much as secondhand cigarette smoke does.

The long-term study was conducted on 279 children from farm worker families, and it is the first one to say that even being one step removed from pesticides can damage the lungs of children. Earlier studies have inspected effects on grownups, who spray the chemicals or work in fields where in the pesticides are applied.

The co-author of the study, Brenda Eskenazi, an epidemiologist at UC Berkeley, said this was the first time ever that a residential population was examined, and that too, a residential population of children.

The Center for the Health Assessment of Mothers and Children of Salinas, CHAMACOS, has conducted the long study. During the broader study that started nearly 15 years back with 601 pregnant women in the Salinas Valley, the researchers followed the children since birth.

Earlier studies from the same group have turned up correlations between exposure of organophosphate to pregnant women and shorter-duration pregnancies, reduced reflexes in their babies, and lower cognitive function in little grown up children.

During the present study, published online in the journal Thorax, on Thursday, the researchers tested pregnant women for chemicals in their urine that belong to metabolizing organophosphates. They tested their kids at 5 intervals, from 6 months of age to 5 years, and then the children were given a number of exhalation-measuring tests when they become 7 year old.

They found a notable connection between lower exhalation rates and higher levels of organophosphate metabolites.