Pollution may lead to a life of crime

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http://www.newscientist.com/ns/970531/news.html

Pollution may lead to a life of crime

May 31, 1997

By Alison Motluk

Environmental pollution makes a big contribution to violent crime and

antisocial behaviour, according to a provocative new analysis by an American

political scientist. He believes that toxic chemicals, in particular metals

in water supplies, can disrupt the neurological control mechanisms that

normally inhibit our violent urges. Other experts are intrigued but want to

see more evidence.

Conventional theories link crime with social, economic and psychological

factors. But Masters of Dartmouth College in Hanover, New Hampshire,

says that these factors cannot fully explain why some counties in the US

have only 100 violent crimes per 100 000 people each year, while others have

over 3000. Data on environmental pollution can account for a lot of the

remaining variation, he claims.

Masters analysed a wide range of statistics including crime figures from the

FBI and information on industrial discharges of lead and manganese, both

into water and into the atmosphere, compiled by the Environmental Protection

Agency.

After controlling for conventional variables such as income and population

density, he found that environmental pollution seems to have an independent

effect on the rate of violent crimes--defined as homicide, aggravated

assault, sexual assault and robbery. Counties with the highest levels of

lead and manganese pollution typically have crime rates three times the

national average, says Masters. " The presence of pollution is as big a

factor as poverty, " says Masters, whose analysis will appear as a chapter in

the book Environmental Toxicology, to be issued later this year by the

publisher Gordon and Breach.

When brain chemistry is altered by exposure to toxic metals, Masters argues,

our natural violent urges may no longer be restrained. " It's the breakdown

of the inhibition mechanism that's the key to violent behaviour, " he claims.

Masters points to experiments on cell cultures which have shown that lead

partly incapacitates glial cells, which are responsible for " housekeeping "

in the brain, mopping up unwanted chemicals ( " Brain cells hit the big time " ,

New Scientist, 5 February 1994). And in people suffering from calcium

deficiency, which afflicts some of America's poorest citizens, manganese

inhibits the uptake of the neurotransmitters serotonin and dopamine in parts

of the brain. These chemicals are known to control impulsive behaviour.

Masters thinks that a major source of lead and manganese is the pipes that

carry water to houses. Soils contaminated with lead and other toxins may

also contribute, he says.

Alastair Hay, a chemical pathologist at the University of Leeds, says that

Masters's theory is plausible, but notes that people who live in areas of

high toxic discharges do not necessarily absorb more toxins.

" This quite likely has something in it, " says Ken Pease, director of the

Applied Criminology Research Unit at the University of Huddersfield. " But I

think the approach badly needs individual level data to nail it down. "