1.   Mr Birchall also knew that acid waters, which contain higher levels of aluminium, are lethal to fish.

2.   The scallop beds at Pentland Firth, between Orkney and mainland Scotland, contained unacceptable levels of cadmium and were declared unfit for human consumption.

3.   Bidis contain higher levels of tar, nicotine and carbon monoxide than regular cigarettes do, according to the national centers.

4.   Birth-control pills that contain high levels of progesterone, which regulates the menstrual cycle, can depress desire and cause moodiness.

5.   Both contain enhanced levels of the building blocks of vitamin A.

6.   Cassidy said waste rock from the mine would contain high levels of sulfides that could leak into rivers upstream from the park and foul Yellowstone for centuries.

7.   Chocolate, a new report indicates, contains high levels of catechins, substances with antioxidant properties that may help fight cancer and heart disease.

8.   Each category contains several levels of instruction.

9.   Environmental activists quote experts as saying that sewage sludge contains toxic levels of lead, cadmium mercury and PCBs, making it a dangerous fertilizer.

10.   Even if the product did contain high levels of dissolved oxygen, a notion that chemists dismiss, it would be of no medicinal use.