Nobody bats an eye when a student in the United States borrows $100,000 to pay for a law degree, MBA or MD. Although that burden appears intimidating, the salaries these professions eventually pay make six-figure debts seem a good investment in the future.

Not so for scientists. Stipends for postdoctoral fellows in the United States, hovering around $35,000–45,000, are often less than those earned by some professionals with only an undergraduate education. When loan repayments kick in, young scientists feel the squeeze — especially as they cannot expect a better salary until they achieve tenure, sometimes a decade down the road.

This financial burden could be one of the reasons why the number of US-born students pursuing research careers has declined over the past decade. And it could explain why scientific research hasn't succeeded in attracting many minorities. Why go through the education and face a career saddled with long odds and large debt, when a professional degree could yield double or triple the salary — and without the prospect of never-ending postdocs?

Comparing the United States with England is interesting. Graduates leaving university with large debts due to student loans are a more recent phenomenon in a country that used to have free tuition in higher education and grants for living expenses. A recent report from Research Councils UK shows that, since loans were introduced, fewer students have been interested in pursuing relatively poorly paid research careers.

Attempts to mitigate the problem are being made in the United States. Last week the National Institutes of Health called for applications for its annual programmes that offer help with student-loan repayments of up to $35,000 a year to individuals working on government-funded research. These payments are a welcome start, but are very limited in the research fields they cover. Programmes with a wider remit might help turn around the decline. And if companies began to offer assistance with repayments, that might make science as attractive as business management and law.