Research Product

Static, acute toxicity tests were conducted with mysids (Mysidopsis bahia) and 11 used drilling fluids (also called drilling muds) obtained from active drilling platforms in the Gulf of Mexico in U.S. waters. Each whole mud was tested, along with three phases of each mud: a liquid phase with particulate materials removed, a suspended particulate phase composed of soluble and lighter particulate fractions and a solid phase composed mainly of drill cuttings and rapidly settling particulates. These muds represented seven of the eight generic mud types described by the U.S. Environmental Protection Agency for use on the U.S. Outer Continental Shelf. Based on volume:volume preparations of the drilling muds in seawater, the lowest 96-hour LC50s obtained were 26 ul/l for whole mud, 11,400 ul/L for the liquid phase, 726 ul/L for the suspended particulate phase and 1,456 ug/l for the solid phase. The toxicity of the 11 muds tested was apparently increased by the presence of aliphatic components.