Both the Predators and the Aliens could potentially carry dangerous toxins or exotic strains of virus or bacteria to which they were long immune but humans were not.

These ciliated tubules pump water carrying surplus ions, metabolic waste, toxins from food, and useless hormones out of the organism through openings known as nephrostomes.

The primitive circulatory systems of the early Minervan fish couldn't cope with the dual workload of carrying enough oxygen to the cells, and of carrying wastes and toxins away from the cells - not if progress toward anything more advanced was going to be made, anyway.

The choking black smoke that the firefighters encountered probably carried aldehydes, cyanide and other toxins from burning wood, plastic and lineoleum.

Some of the declining species breed in bodies of water too small to support fish, and toads carry toxins that keep them safe from fish predation.

They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells.

Charcoal is also a byproduct from trees so it does not carry toxins such as mercury and chromium.

Nonpoint source pollution is pollution that occurs when runoff from streets, lawns, and other areas nearby a waterway carries toxins, chemicals, and silt into lakes, rivers, and oceans causing pollution and buildup of sediment.