Sunday, July 08, 2007

ya think?

The washington post has an article about linking lead exposure to criminal activity.
"Sixty-five to ninety percent or more of the substantial variation in violent crime in all these countries was explained by lead."

1 comment:

Anonymous said...

Good to know there is someone dedicated to investigating environmental contributors to crime.

I scanned the most recent paper by Rick Nevin cited in the Post, and a few things should be mentioned. The study is ecological, which implies that exposures and outcomes are measured in different groups of people and then compared. No matter the findings, this study design does not provide strong evidence for an association. There may be other factors associated with both the exposure (lead intake via ingestion and inhalation) and the outcome (violent crime) which confound the observed association. For example, children growing up at the time when these lead exposures were measured may have lived with poorly-educated parents and with odds stacked against their own opportunities to pursue their dreams. Then there is a question of biological plausibility. Ethically, one could never conduct tests in humans to see whether lead ingestion increases violence. From animal studies, we have evidence that lead hinders neurologic development, but no data were cited about aggressive behaviors after lead exposure. Crime is also a complex behavioral response. It would be useful to understand the motivations and circumstances behind each violent crime. I do not know enough about studies of crime to be at all familiar with this. Could psychologists get more insight into the behaviors leading someone to commit a crime? Are more crimes intentional or mistakes of circumstances? If psychologists could describe disordered thought processing among criminals, and if these were comparable to those occurring after lead intake, there might be a stronger case.

The Washingtonian ran a similar story about the tragedy of city children growing up in poverty and with high lead exposures impairing their intellectual development. I would not write off this hypothesis, and I think that more research should be done about potential effects of cumulative lead exposure on behavior with the aim of looking for better means of prevention and remediation.

It seems odd that Nevin writes alone with no no co-authors and works as a consultant. I wonder if he has ever approached the public health research community to speak with others who study the effects of lead on behavior. Not seeing co-authors gives a warning signal that Nevin may be more of a lone wolf with whom other, credible health researchers do not agree. However, this is only speculation.