What are the substances dangerous for the aquatic environment?
Synthetic chemicals, while bringing benefits to society, can sometimes be hazardous, raising concerns for human health and the environment depending on their pattern of use and the potential for exposure. These comprise a wide range of industrial and household chemicals, metals, pesticides and pharmaceuticals. Certain types of naturally occurring chemicals, such as metals, can also be hazardous.
Substances arrive into the waterways, lakes and seas, both directly and indirectly through a range of sources including agriculture and aquaculture, industry, oil exploration, mining activities, transport, shipping and waste disposal, as well as our own homes.
What are the effects of hazardous substances in water on the environment and on humans?
Depending on the level of exposure, hazardous substances that can have negative effects on aquatic life at molecular, cellular, tissue, organ and ecosystem level are documented by various information sources. For example, substances that interfere with hormones (known as endocrine disruptors have been shown to impair reproduction in fish and shellfish in Europe, raising concerns for fertility and population survival. The impact of organochlorines upon sea birds and marine mammals is also well documented, as is the toxicity of metals and pesticides to freshwater biota.
From a socio economic point of view, such impacts diminish the services provided by aquatic ecosystems, and consequently the revenue that can be derived from them.
For humans, exposure to man-made chemicals has been linked to a range of chronic diseases, including cancer as well as reproductive and developmental impairment. Such exposure can be linked to the presence of hazardous substances in water, through the ingestion of contaminated drinking water and the consumption of contaminated freshwater fish and seafood.
What are the present challenges regarding hazardous substances in the aquatic environment?
In many cases, declining contamination trends of aquatic systems are observed. Some hazardous substances, like for example mercury, tributyltin and polyaromatic hydrocarbons, which are hydrophobic, tend to accumulate in sediment and in living organisms, and so are more detectable and measurable in these media than in water and if measurement were made in the water column only, the risks to the aquatic environment could be therefore underestimated.
Data showed for example that hazardous substances could still be found in 2007 at high concentrations, among others, in three of the European seas. This observation reflects the persistence in the aquatic environment of substances like DDT, hexchlorobenzene (HCB), lindane and PCBs, despite the fact these are all four banned within Europe sometimes, like for DDT, since several decades. In certain locations, some metal like mercury concentrations also still exceeded the maximum levels set by legislation. In many cases however, declining trends are observed. .
A key measure for reducing the level of contamination, and thus the required needs of purification, for Europe’s drinking water, says the report, is the establishment of safeguard or protection zones around the sources and must be associated with regulatory competencies to further control polluting activities.
For some co-called “emerging pollutants”, awareness and an understanding of their potential effects is still currently incomplete, or have developed only recently. These include substances that have existed for some time, such as pharmaceuticals and personal care products, but also relatively new substances, such as nanomaterials. Their inclusion in routine monitoring programmes has so far been limited, making it difficult to robustly assess the risks to the environment and human health, and thus to justify their regulation and better monitoring. Such targeted monitoring across the EU would be desirable to ensure timely awareness of these potentially problematic substances. and should be supported by European research studies.
How can the presence of hazardous substances in the aquatic environment be further reduced?
Whilst controls ‘at source’ are desirable, it is very likely that other measures to attenuate the emission of hazardous substances to water will remain essential. For many hazardous substances, information on industrial emissions to water must, in theory, be reported under the European Pollutant Release and Transfer Register (E-PRTR), but this reporting is still incomplete.
The E.U. Regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) adopted in 2006, also improved the protection of human health and the environment from the risks posed by chemicals and plays a key role in this respect.
Although controls “at the source” remain necessary, further measures to unerstand and mitigate the release of all hazardous substances into water remain essential. Such measures include advanced wastewater treatment, urban storm water controls and specific agro-environmental practices. Reducing emissions of hazardous substances has been shown to yield economic and societal benefits.
New tools for monitoring, restricting emissions, for substitutions and developping alternative products or for decontamination are also under further development.