Oil prices dropped another 5 percent to a seven-month low on Tuesday, extending the steepest two-day slide since 2004 as mounting economic turmoil sent investors fleeing to safer havens. US crude for October settled down $4.56 at $91.15 a barrel, adding to losses of more than $5 on Monday. Prices have dropped about 10 percent in two days, the biggest slide since Dec. 2, 2004. November Brent crude fell $5.02 to $89.22 a barrel. Slowing demand in the United States and other top consumer nations has sent crude prices tumbling from record highs over $147 a barrel in July. In Vienna, OPEC on Tuesday cut its world oil demand growth forecast for 2008 to 1.02 percent from 1.17 percent previously, in the face of falling demand in the United States, the world's biggest energy consumer. In its latest monthly report, OPEC also trimmed its forecast for growth in world oil demand next year to 1.00 percent from 1.03 percent in its previous report. “In 2009, world oil demand is forecast to grow by 0.9 million barrels per day (bpd) to average 87.7 million bpd,” the report said. All of that additional demand will come from non-OECD countries, while demand from industrialized countries will decline.