Could it harm marine organisms?

Key Points

  • Whether a spilled, toxicPoisonous; can injure or kill people or other organisms. chemical could harm marine organisms depends on what happens to it in the water. If it is denser than water, it will sink and could threaten bottom-dwelling organisms (such as shellfish). If it is less dense than water, it will float and could threaten organisms that spend time at the surface (such as seabirds and marine mammals).
  • A chemical that dissolves into the water has the potential to harm organisms at all levels in the water, but only if its concentrationThe amount of a chemical present in a given weight or volume of air. Concentration of a gas in air may be expressed in units such as parts per million (by volume) or milligrams per cubic meter. in the water reaches harmful levels.
  • Generally, a toxic chemical will do greater harm if it remains in contact with water organisms for a longer time. Longer contact is more likely in a small, still water body (such as a pond) where dilution is slower.
  • CAMEO 365betÓéÀÖ shows marine toxicity data for some substances. It also provides specific gravityThe ratio of the density of a substance at a given temperature to the density of water at the same temperature. A substance with a specific gravity greater than 1.0 will sink (rather than float) in water. and water solubilityA measure of a chemical's ability to dissolve in water. If a chemical is highly soluble, it will dissolve easily into water., which indicate whether a substance will dissolve and whether it will float or sink in water.

Backgrounder

During a response, you might need to quickly assess whether a spilled chemical could harm animals and plants living in the water. For example, if a toxic chemical spills into the water where there's an important fishery, you might need to predict how badly the fish could be affected.

How badly a particular species of water animal or plant could be harmed by a spilled chemical depends on the:

  1. Chemical's toxicity (harmfulness) to that species. Learn more about toxicityLearn more about toxicity

    365betÓéÀÖ that are more toxicPoisonous; can injure or kill people or other organisms. have greater potential to do harm. Additionally, be aware that:

    • A toxic chemical generally will do more harm if it stays in contact with an animal or plant for a longer time. For example, a toxic chemical spilled into a small pond is likely to harm water animals more severely than the same chemical spilled into a river, where currents will soon dilute it and wash it downstream.
    • Some species are more sensitive to a particular chemical than other species.
    • Animals and plants can be more sensitive to a chemical at one stage in their life. For example, larvae, eggs, and very young animals can be more sensitive than adults.

    Sometimes only a little information about a chemical's toxicity to a given organism exists—or no information at all. Sometimes specialists must use what is known about one species to judge possible harm to another. For example, they may judge that a chemical that is relatively toxic to people will also be relatively toxic to marine animals.

    You can get information about a chemical's toxicity to water organisms from the External link., which are prepared by the International Programme on Chemical Safety and the European Commission. To view a chemicals' ICSC from CAMEO 365betÓéÀÖ, search for the chemical, go to its chemical datasheet, then click on the external website link for the International Chem Safety Card (if available). Then scroll down to the "Environment" section.

    Environment section from the IPCS International Chemical Safety Card for vinyl acetate (monomer).

  2. Pathways it could follow to come into contact with organisms of that species. Learn more about possible pathwaysLearn more about possible pathways

    How a chemical could come into contact water animals or plants depends on:

    What happens to the chemical after it spills into the water.

    • A chemical that's less dense than water will float on the water surface. There, it could come into contact with organisms found on or near the water surface (such as seabirds that often rest on the surface and marine mammals that must come to the surface to breathe). It will be unlikely to harm organisms that live deep in the water.
    • A chemical that's denser than water will sink towards the bottom, where it could come into contact with organisms that live deep in the water or on the bottom. It will be unlikely to harm organisms that live at or near the surface. For example, it will be more likely to harm shellfish beds.
    • A chemical that dissolves into the water has the potential to harm organisms at all levels in the water, but only if its concentration in the water reaches harmful levels. Concentrations of a dissolved chemical are likely to be highest in small bodies of water (such as canals and ponds) and in locations with little flushing action from currents and tides.
    • Check the chemical's datasheet in CAMEO 365betÓéÀÖ to see the specific gravityThe ratio of the density of a substance at a given temperature to the density of water at the same temperature. A substance with a specific gravity greater than 1.0 will sink (rather than float) in water. (to find out whether it will float or sink) and the water solubilityA measure of a chemical's ability to dissolve in water. If a chemical is highly soluble, it will dissolve easily into water. (to find out whether it dissolves in water).
    When and where in the environment the organisms of concern are found.
    • Some animals may be present in an area year-round, while others may be present only at certain times (when nesting or spawning, for example). Some animals may be present in an area only at certain times of day. For example, an animal might normally feed at sea during the day and return to a coastal area at night to rest.
    • If you don't already know what animals and plants are of concern in the area at the time of the spill, check with local experts. You also can check External link. of the area to see what's present. The map shows the locations of important animal populations and habitats, and the months when each species is present in the area.

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