Russian oil spills come in drips and trickles, instead of dramatic explosions. But the Associated Press reports that oil companies there spill at least 1 percent of all oil produced every year — "equivalent to one Deepwater Horizon-scale leak about every two months," the AP says.

Why have you never heard about this? Well, for one, the Russian government has no data on oil spills and doesn't impose penalties unless an individual spill is over eight tons. But, as the AP explains, these slow-roll spills are rarely dramatic enough to cross that threshold, so the companies get off scot-free.

Oil spills in Russia are less dramatic than disasters in the Gulf of Mexico or the North Sea, more the result of a drip-drip of leaked crude than a sudden explosion. But they're more numerous than in any other oil-producing nation including insurgency-hit Nigeria, and combined they spill far more than anywhere else in the world, scientists say.

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