Do contaminants cause pollution? To what extent do you agree?

Contaminants in the atmosphere appear to have harmful effects on neurodevelopment and cognitive function. When Lilian

Calderón-Garcidueñas

discovered abundant hallmarks of Alzheimer’s disease in a batch of human brain samples a few years ago, she

initially

wasn’t sure what to make of it. The University of Montana neuropathologist had been studying the

brains

as part of her research on environmental effects on neural development, and

this

particular set of samples came from autopsy examinations carried out on people who had died suddenly in

Mexico

City, where she used to work as a researcher and physician.

Although

Calderón-Garcidueñas

had collected much of the tissue herself

while

attending the autopsies in

Mexico

, the light-microscope slides she was analyzing had been prepared by her colleagues, so she was in the dark about what patient each sample came from. By the end of the project, she’d identified accumulations of the Alzheimer’s

disease–associated

Add a hyphen

disease–associated

show examples

proteins amyloid-ß and hyperphosphorylated tau in almost all of the 203

brains

she studied. “When I started opening envelopes to see who [each sample] belonged to . . . I was devastated,” she says. The people whose

brains

she’d been studying were not only adults

,

Remove the comma

apply

show examples

but teens and even children. The youngest was 11 months old. “My first thought was, ‘What am I going to do with

this

? What am I going to tell people?’” she says. “I was not expecting

such

a devastating, extreme pathology.” Despite her shock,

Calderón-Garcidueñas

had a reason to be on the lookout for signs of a disease usually associated with the elderly in these samples. For the

last

three decades, she’d been studying the health effects of

Mexico

City’s notoriously polluted air—a blight that earned the capital the dubious distinction of most polluted megacity on the planet from the United Nations in 1992. During that time,

she’s

Unnecessary verb

she

show examples

discovered many links between exposure to air pollution and signs of neural damage in animals and humans.

Although

her findings are observational, and the pathology of proteins

such

as amyloid-ß is not fully understood,

Calderón-Garcidueñas

argues that air pollution is the most likely culprit behind the development of the abnormalities she saw in her postmortem samples—plus many other detrimental changes to the

brains

of

Mexico

City’s residents.