OAKLAND — Destined for American kitchens, planks of birch and poplar plywood are stacked to the ceiling of a cavernous port warehouse. The wood, which arrived in California via a cargo ship, carries two labels: One proclaims "Made in China," while the other warns that it contains formaldehyde, a cancer-causing chemical.

Because formaldehyde wafts off the glues in this plywood, it is illegal to sell in many countries — even the one where it originated, China. But in the United States this wood is legal, and it is routinely crafted into cabinets and furniture.

As the European Union and other nations have tightened their environmental standards, mostly in the last two years, manufacturers — here and around the world — are selling goods to American consumers that fail to meet other nations' stringent laws for toxic chemicals.

Wood, toys, electronics, pesticides and cosmetics are among U.S. products that contain substances that are banned or restricted elsewhere, particularly in Europe and Japan, because they may raise the risk of cancer, alter hormones or cause reproductive or neurological damage.

Michael Wilson, a professor at UC Berkeley's Center for Occupational and Environmental Health, said the United States is becoming a "dumping ground" for consumer goods that are unwanted and illegal in much of the world. Wilson warned earlier this year in a report commissioned by the California Legislature that "the United States has fallen behind globally in the move toward cleaner technologies."
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One birch plank from China, bought at a Home Depot store in Portland, gave off 100 times more formaldehyde than legal in Japan and 30 times more than allowed in Europe and China, according to July tests conducted by a lab hired by an Oregon-based wood products manufacturer. Formaldehyde exposure has been shown in human studies to cause nose and throat cancer and possibly leukemia, as well as allergic reactions, asthma attacks, headaches and sore throats.