30 March, 2017
Dr Nick Wilson, of the University of Otago's Department of Public Health in Wellington, said the oil industry, and specifically Associated Octel which supplied the lead added to New Zealand petrol, should take some of the blame for the damage caused before lead was banned from being added to petrol in 1996.
Aaron Reuben, M.E.M., of Duke University, Durham, N.C., and colleagues conducted a study that included participants of the Dunedin Multidisciplinary Health and Development Study, an investigation of health and behavior of individuals born between April 1972 and March 1973 in Dunedin, New Zealand. This could have an effect on the type of jobs and the level of income of people who had exposure to lead (Pb) in childhood.
In Reuben's study, every 5 microgram increase in lead concentration in the blood at age 11 corresponded to a drop in IQ of 1.6 points at age 38 - primarily because of a drop in scores on perceptual reasoning and working memory. It further noted that lead levels in the blood are higher in childhood while the loss of IQ happens in adulthood.
"This is despite the fact that in the 1970s this same study [the Dunedin Study] was one of the best in the world at showing that lead was damaging the IQ of children". Each person had their blood lead levels measured when they were 11 years old, and the researchers followed up with blood tests about decades later, when they were 38.
Not surprisingly, participants with blood lead levels above 10 µg/dL scored -2.73 mean IQ points lower (95% CI -4.34 to -1.12, P 0.001) than their peers with normal or lower blood lead levels, after adjusting for childhood IQ level and other factors. This suggests a link between work achievement and lower IQ due to childhood lead exposure, the researchers said.
According to Reuben, New Zealand had some of the highest lead and gasoline levels of anywhere in the world.
"Lead exposure is very rare in Kiwi children today". People in New Zealand actually exhibit the exact same situation, according to a renowned Dunedin study.
"For communities that have experienced collective lead exposure events and for countries where lead exposures are still routinely above health standards, the findings raise questions about the reasonable duration and magnitude of public responses".More news: Burglary at Bellagio Hotel and Casino prompts lockdown on Vegas strip
Children playing outside near roads either inhaled lead-laden dust or swallowed small amounts of leaded soil.
Lead is a powerful neurotoxin that can accumulate in a child's bloodstream, then settle in the bones, teeth and soft tissues and build up in the body.
The study also compared changes in social standing using a measure from the New Zealand government that plots families on a 6-point scale. The results don't apply only to the generation now entering middle age, Bellinger says that lead exposure could potentially affect more generations. "If everyone takes a hit from environmental pollutants, society as a whole suffers".
This was slightly higher than the historical "level of concern" for lead exposure in the 1990s.
CITATION: "Association of Childhood Blood Lead Levels With Cognitive Function and Socioeconomic Status at Age 38 Years and With IQ Change and Socioeconomic Mobility Between Childhood and Adulthood", Aaron Reuben, Avshalom Caspi, Daniel Belsky, Jonathan Broadbent, Honalee Harrington, Karen Sugden, Renate Houts, Sandhya Ramrakha, Richie Poulton, Terrie Moffitt. After various statistical controls were applied to the data, "the decline in occupational status is partially but significantly explained by the loss of IQ", he said.
'The cognitive deficits associated with lead persisted for decades, and showed in the kinds of occupations people got, ' he said.
This study was supported in part by grants from the US National Institute on Aging, as well as United Kingdom government grants.