题型：阅读理解 题类：常考题 难易度：普通
江苏省启东中学2020届高三上学期英语期初考试试卷
Children exposed to "safe" levels of air pollution in the womb(子宫) develop brain damage that damages their concentration, a study has shown.
The research is the first too link common pollutants such as nitrogen(氮) dioxide and soot(油烟) to changes in the brains of unborn babies that mean they may struggle to focus at school in later life. The findings suggest that even comparatively clean city air could lead to worse academic performance and an increased risk of mental health problems such as addition or attention deficit hyperactivity disorder(缺陷多动障碍).
In recent years scientists have found that children who grow up surrounded by air pollution are more likely to have a broad range of "neuro(神经)developmental" difficulties, including autism and various kinds of cognitive(认知) damage. However, only a handful of studies have looked at the ways in which the poisonous gases and microscopic particles(微粒) that mothers and young children take in affect the brain during critical stages of its growth.
A group led by Monica Guxens, of the Barcelona Institute for Global Health, found that exposure to air pollution before birth appeared to have slowed the development of several brain regions that play an important role in people's capacity for selfdenial and sustained effort. This lack of inhibition could in turn cause "cognitive delays" when the children get older, the scientists argue in Biological Psychiatry.
"We need this function in our daily life," Dr. Guxens said. "It controls our impulses(冲动) and our selective attention. Children need it to learn and for making decisions in later life. We're interested to see what will happen: is there going to be an impact on their academic work, are there going to be clinical implications? It might be that this will lead to problems later."
The results were drawn from MRI scans of 873 children between the ages of six and ten in Rotterdam. Even though 99.5 percent of their mothers had lived with nanoparticle pollution levels well below EU legal limits while they were pregnant the pollution still appeared to have taken its toll(伤亡人数).
Children who had been exposed to more pollution in the womb did worse on a test of their ability to block out irrelevant stimuli(刺激). They also had thinner outer layers in the precuneus(楔前叶) and the rostral middle frontal regions of their brains, both of which are involved in cognitive inhibition, which refers to the mind's ability to tune out stimuli that are irrelevant to the task at hand or to the mind's current state.
Experiments on animals show that socalled fine particles are able to pass through the placenta and affect the brain of the fetus(胎儿). Dr Guxens said there were probably no such thing as a safe concentration of air pollution.
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