Exposure to high pollution levels during pregnancy may increase risk of having child with autism

AutismWomen in the U.S. exposed to high levels of air pollution while pregnant were up to twice as likely to have a child with autism as women who lived in areas with low pollution, according to a new study from Harvard School of Public Health (HSPH). It is the first large national study to examine links between autism and air pollution across the U.S.

“Our findings raise concerns since, depending on the pollutant, 20% to 60% of the women in our study lived in areas where risk of autism was elevated,” said lead author Andrea Roberts, research associate in the HSPH Department of Social and Behavioral Sciences.

The study appeared online June 18, 2013 in Environmental Health Perspectives.

Exposure to diesel particulates, lead, manganese, mercury, methylene chloride and other pollutants are known to affect brain function and to affect the developing baby. Two previous studies found associations between exposure to air pollution during pregnancy and autism in children, but those studies looked at data in just three locations in the U.S.

The researchers examined data from Nurses’ Health Study II, a long-term study based at Brigham and Women’s Hospital involving 116,430 nurses that began in 1989. Among that group, the authors studied 325 women who had a child with autism and 22,000 women who had a child without the disorder. They looked at associations between autism and levels of pollutants at the time and place of birth. They used air pollution data from the U.S. Environmental Protection Agency to estimate women’s exposure to pollutants while pregnant. They also adjusted for the influence of factors such as income, education, and smoking during pregnancy.

The results showed that women who lived in the 20% of locations with the highest levels of diesel particulates or mercury in the air were twice as likely to have a child with autism as those who lived in the 20% of areas with the lowest levels.

Other types of air pollution—lead, manganese, methylene chloride, and combined metal exposure—were associated with higher autism risk as well. Women who lived in the 20% of locations with the highest levels of these pollutants were about 50% more likely to have a child with autism than those who lived in the 20% of areas with the lowest concentrations.

Most pollutants were associated with autism more strongly in boys than girls. However, since there were few girls with autism in the study, the authors said this finding should be examined further.

Senior author Marc Weisskopf, associate professor of environmental and occupational epidemiology at HSPH, said, “Our results suggest that new studies should begin the process of measuring metals and other pollutants in the blood of pregnant women or newborn children to provide stronger evidence that specific pollutants increase risk of autism. A better understanding of this can help to develop interventions to reduce pregnant women’s exposure to these pollutants.”

 

Reference

Roberts AL, Lyall K, Hart JE, Laden F, Just AC, Bobb JF, Koenen KC, Ascherio A, Weisskopf MG. Perinatal air pollutant exposures and autism spectrum disorder in the children of Nurses’ Health Study II participants. Environmental Health Perspectives, online June 18, 2013.

 

Diesel Fumes Pose Risk to Heart as Well as Lungs, Study Shows

Tiny chemical particles emitted by diesel exhaust fumes could raise the risk of heart attacks, research has shown:

Scientists have found that ultrafine particles produced when diesel burns are harmful to blood vessels and can increase the chances of blood clots forming in arteries, leading to a heart attack or stroke.

The research by the University of Edinburgh measured the impact of diesel exhaust fumes on healthy volunteers at levels that would be found in heavily polluted cities.

Scientists compared how people reacted to the gases found in diesel fumes – such as carbon monoxide and nitrogen dioxide – with those caused by the ultrafine chemical particles from exhausts.

The research, funded by the British Heart Foundation, showed that the tiny particles, and not the gases, impaired the function of blood vessels that control how blood is channelled to the body’s organs.

The ‘invisible’ particles – less than a millionth of a metre wide – can be filtered out of exhaust emissions by fitting special particle traps to vehicles. Particle traps are already being fitted retrospectively to public transport vehicles in the US to minimise the potential effects of pollution.

The results are published in the European Heart Journal.

Dr Mark Miller, of the University of Edinburgh’s Centre for Cardiovascular Science, said: “While many people tend to think of the effects of air pollution in terms of damage to the lungs, there is strong evidence that it has an impact on the heart and blood vessels as well.

“Our research shows that while both gases and particles can affect our blood pressure, it is actually the miniscule chemical particles that are emitted by car exhausts that are really harmful.

“These particles produce highly reactive molecules called free radicals that can injure our blood vessels and lead to vascular disease

“We are now investigating which of the chemicals carried by these particles cause these harmful actions, so that in the future we can try and remove these chemicals, and prevent the health effects of vehicle emissions”

Researchers want environmental health measures that are designed to reduce emissions to be tested to determine whether they reduce the incidence of heart attacks.

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, said: “We’ve known for a long time that air pollution is a major heart health issue and that’s why we’re funding this team in Edinburgh to continue their vital research. Their findings suggest that lives could be saved by cutting these harmful nanoparticles out of exhaust – perhaps by taking them out of the fuel, or making manufacturers add gadgets to their vehicles that can trap particles before they escape. The best approach isn’t clear yet.

“For now our advice remains the same – people with heart disease should avoid spending long periods outside in areas where traffic pollution is likely to be high, such as on or near busy roads.”

 

Reference

Mills NL, Miller MR, Lucking AJ, Beveridge J, Flint L, Boere AJ, et al. Combustion-derived nanoparticulate induces the adverse vascular effects of diesel exhaust inhalation. Eur Heart J. 2011 Jul 13. [Epub ahead of print]