Hazardous Chemicals

The Problem

Many hazardous substances enter the sewage system from a variety of different sources. These include chemicals that go down the toilets, sinks and drains as well as effluent from industry, leachate from landfills and run-off from the land.

As sewage treatment works are not designed to remove all of these chemicals, many are still present in the effluent that is discharged into rivers and oceans. This chemical loading to the rivers and oceans is increased by the chemicals that by-pass the sewage system and enter directly into the rivers or sea through different routes such as direct run-off.

This cocktail of chemicals can be very complex and can include heavy metals, PCB’s, pesticides and other halogenated hydrocarbons. A whole range of harmful effects have been documented but a great deal is still unknown about the damage these chemical mixtures can cause to wildlife or the hazard they present to recreational water users. Many of these pollutants persist in the environment and can accumulate in organisms. This bioaccumulation can cause problems higher up the food chain as concentrations of toxins can reach more hazardous levels.

Some chemicals found in sewage effluent can affect the hormonal system of aquatic animals. These ‘endocrine disrupting compounds’ have been linked to effects such as the feminisation of male fish. The effect these compounds have on exposed humans is unknown.

The Solution

Reducing the pollution at the source is generally easier and cost more effective than trying to introduce methods to remove pollutants from effluents, which can be technically very difficult. Improved legislation on harmful chemical usage in industry is needed and less hazardous alternatives need to be investigated to allow the worst chemicals to be phased out. It’s not just industry that needs to clean up it’s act. Everyone needs to consider what they are putting down their drains. By shifting to greener, less environmentally damaging products for cleaning and washing, the impact you have on the marine environment can be significantly reduced.