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As prices for oil, gas and metals take a hit, they are giving the countries that produce these commodities a run for their money.

The currencies of countries like Canada, Australia and Chile -- sometimes called "commodity currencies" because they are so heavily supported by the export sales of natural resources -- are starting to fall as commodities prices wobble off recent highs.

Since peaking in mid-May, the CRB index, a broad measure of the performance of commodities compiled by the Commodity Research Bureau, has fallen about 15%. Oil is down 21% from its high on July 14, while natural gas is down 59% in 2006. Gold, while up 14% for the year, is down about 18% from its 12-month high. Copper is off about 14% since May.

All of this stems from hints of slowing growth in the U.S. economy, which translates to less demand for energy and other commodities. Last week, the stock market closed lower as investors fretted over softer-than-expected economic data. In an unexpected twist, hedge fund Amaranth Advisors reported big losses after betting wrong on natural gas.

The broader market shrugged that off, but the Dow Jones Industrial Average -- which until recently was approaching record levels -- still fell 52.67 points, or 0.5%, during the week to 11508.10, leaving it up 7.4% for the year.

Investors have done well buying shares of natural-resources companies like miners and loggers for the past five years. But with the commodity boom looking shaky, nervousness has risen. Also, concern about speculators exiting these markets could cause more havoc.

Will commodity prices bounce back soon? A look at commodity currencies would indicate that such a surge isn't likely anytime soon.

"The next five to six quarters are going to be tough," says Abhijit Chakrabortti, head of global investment strategy at J.P. Morgan Chase & Co. "Where you could get a lot of concern is Canada and Australia."

Adding to the vulnerability of these main commodity currencies is how speculators such as hedge funds trade in the foreign-exchange markets. Often, they use complex derivatives that can be difficult to sell in volatile markets. When faced with selling pressure from either redemptions or margin calls, these investors are more likely to dump their actual currency holdings than the derivatives, because it is easier.

"There's infinitely more liquidity in the currency markets," says Robert Kowit, head of global fixed-income investments at Federated Investors Inc.

The Canadian and Australian dollars, up about 42% and 48%, respectively, since the end of 2001, have edged off their highs in the past few months. The Canadian dollar, called the "loonie" because the dollar coin features the common loon, has softened about 1.7% since hitting a high June 12 at just under 1.10 to the U.S. dollar. The Australian dollar has fallen 2.6% to just under 76 U.S. cents from its high of about 78 cents on May 11.

Booming energy prices have helped support the loonie, and Canada sells a great deal of natural gas and oil to the U.S. Many analysts agree that Canada, at least in the short term, could be hit hard if the U.S. economy slows significantly during the next 12 months. Canada relies on selling oil, lumber and cars across the border, but its merchandise trade surplus shrank in July to its lowest level in more than three years.

The loonie's day in the sun may not be over, though. Analysts say it will strengthen again over the longer term -- assuming the U.S. growth cycle starts again in about 18 months. That is because of Canada's wealth of natural resources, especially oil and natural gas, which will continue to be in high demand for years to come.

"Canada has such a strong fundamental bid to its currency that it's hard to see the loonie falling very far," says Carl B. Weinberg, chief economist at research firm High Frequency Economics. "It doesn't mean people can't get killed on a day-to-day basis, though."

John Rothfield, a currency strategist at Bank of America, estimates the Canadian dollar will end 2006 at the current rate of about 1.12 to the dollar but will strengthen to about 1.09 to the dollar -- its 12-month high -- by the end of 2007.

The Australian dollar has a similar outlook. Highly exposed to base metals and precious metals due to its big mining industry, the Australian economy is poised to feel pressure if commodity prices fall further. The Journal of Commerce's base-metal index has fallen about 4% since July and is expected to fall an additional 10% over the next several months, according to Sue Trinh, a currency strategist at RBC Capital Markets in Sydney.

"That would limit the Aussie to go higher," Ms. Trinh says. She argues, however, that Australia's proximity to fast-growing China makes its long-term promise greater than Canada's.

In Latin America, high copper prices helped to push the Chilean peso up about 22% against the dollar since the end of 2001. Recently, economic growth has slowed as copper prices have fallen, prompting the Chilean central bank to lower its forecast for 2006 gross domestic product.

The peso, which in December reached about 510 to the U.S. dollar, has weakened to about 540. Bank of America expects it to soften to 570 in the first quarter of 2007 before ending at about 560 by the end of next year.