Commercial arrangements are rampant throughout medicine. In the past two decades, drug and device makers have paid tens of thousands of doctors and researchers of all specialties. Worried that this money could taint doctors’ research plans or clinical judgment, government agencies, medical journals and universities have been forced to look more closely at deal details.

Image Senator Charles E. Grassley, right, Republican of Iowa, is demanding that the American Psychiatric Association give an accounting of its financing from the pharmaceutical industry. Credit... Doug Mills/The New York Times

In psychiatry, Mr. Grassley has found an orchard of low-hanging fruit. As a group, psychiatrists earn less in base salary than any other specialists, according to a nationwide survey by the Medical Group Management Association. In 2007, median compensation for psychiatrists was $198,653, less than half of the $464,420 earned by diagnostic radiologists and barely more than the $190,547 earned by doctors practicing internal medicine.

But many psychiatrists supplement this income with consulting arrangements with drug makers, traveling the country to give dinner talks about drugs to other doctors for fees generally ranging from $750 to $3,500 per event, for instance.

While data on industry consulting arrangements are sparse, state officials in Vermont reported that in the 2007 fiscal year, drug makers gave more money to psychiatrists than to doctors in any other specialty. Eleven psychiatrists in the state received an average of $56,944 each. Data from Minnesota, among the few other states to collect such information, show a similar trend.

In both states, individual psychiatrists are not top earners, but consulting arrangements are so common that their total tops all others. The worry is that this money may subtly alter psychiatrists’ choices of which drugs to prescribe.

An analysis of Minnesota data by The New York Times last year found that on average, psychiatrists who received at least $5,000 from makers of newer-generation antipsychotic drugs appear to have written three times as many prescriptions to children for the drugs as psychiatrists who received less money or none. The drugs are not approved for most uses in children, who appear to be especially susceptible to the side effects, including rapid weight gain.