Hazardous substances can harm ecosystems and human health. Due to their intrinsic properties, they can accumulate in the marine food web up to levels, which might be toxic to the organisms themselves, or to their predators. Once released to the Baltic Sea environment, hazardous substances can remain there for a very long time.
What are hazardous substances?
Hazardous substances are substances that are toxic, persistent and liable to bioaccumulate, or otherwise give reason for concern - by influencing the hormone or immune systems, for example.
Although monitoring indicates that the loads of some hazardous substances have been reduced considerably over the past ten years, problems still persist. Comprehensive knowledge about the impact of most available chemicals, and their combinations, on human health and the environment is still lacking. The increasing number of these man-made substances is a matter of concern and calls for the application of the precautionary principle.
Hazardous substances accumulate up food webs
Hazardous substances can bioaccumulate in marine food webs up to levels, which might be toxic to the organisms themselves, or to their predators. Thus, even human health might be effected. Sweden's Food Administration has in fact recommended that young women should limit their consumption of Baltic herring and salmon - fish that can accumulate high concentrations of hazardous substances in their fatty tissue.
Seals in the Baltic Sea are now benefiting from declining levels of organic contaminants, although reproductive problems due to the effects of PCBs and dioxins are still widespread. An increasing number of young grey seals are suffering from chronic intestinal ulcers, thought to be caused by contaminants disturbing their immune systems.
The eggshells of seabirds like the guillemot (Uria aalge) have become much thicker since the 1970s, thanks to reductions in DDT concentrations. The white-tailed eagles (Hailaeetus albicilla) of the Baltic are also now breeding almost as successfully as they did before the 1950s, when toxic substances started to take their toll.
Growing evidence suggests that PCBs and persistent halogenated aromatic hydrocarbons have reproductive and immunotoxic effects in wildlife. Effects on the liver, skin, immune systems, reproductive system, gastrointestinal tract and thyroid gland of laboratory rats have been observerd. PCBs are classified as probable human cancer promoters.
For more detailed information on concentrations of heavy metals, lead and PCBs in fish tissues, see the following Indicator Fact Sheets:
Temporal Trends in Contaminants in Herring in the Baltic Sea in the Period 1980–2002
Lead concentrations in fish liver
PCB concentrations in fish muscle
What are hazardous substances used for?
Heavy metals like mercury and cadmium are e.g. used in batteries. Mercury is also used in old thermometers and other laboratory and medical instruments, as amalgam in dental fillings, in biocides, pesticides and fertilisers, industrial and control instruments, lighting appliances (e.g. fluorescent lamps), and electrical equipment (switches, relays).
Nonylphenol (NP)is used almost exclusively as an intermediate in the production of other chemicals, with some 60 % used to make Nonylphenolethoxylates (NPEs) and the remainder to make other NP-derivatives. NPEs are used in a wide range of industry sectors as emulsifiers, dispersive agents, surfactants and wetting agents. The most important sector is the industrial and institutional cleaning sector, including domestic cleaning. Other sectors using significant amounts of NPE include emulsion polymerisation, textiles, 'captive use' - i.e. use in the chemical industry to synthesise nonylphenol-derivatives for example - and leather.
The main uses of short chained chlorinated paraffins (SCCP) in Europe were in metal working fluids, as plasticiser in paints, coatings and sealants, as flame retardant in rubbers and textiles, and in leather processing (fat liquoring). But due to an increasing unspecified “other” use new product developments using SCCP cannot be excluded. Less environmentally hazardous substitutes are available for most major applications.
Where and how are hazardous substances emitted, discharged and lost?
· Hazardous substances are emitted from all stages of the product chain - from the raw material and the production processes, from the use of products and from the handling of products as waste.
· Emissions from point sources, like land based industrial installations and mines have been reduced substantially. However, the importance of emissions from diffuse sources, like consumer products, is increasing.
· Contaminants also originate from shipping. Special problems include the anti-fouling agents used in paints, and illegal oil releases.
· The main pathways of hazardous substances to the marine environment are industrial wastewater, municipal wastewater - discharged directly or transported in rivers- and atmospheric deposition. Water pollution is closely monitored by all coastal states, but the methods differ from country to country, and improvements are needed.
· Inputs from the atmosphere are still high, particularly where heavy metals are concerned. Considering the prevailing wind directions, these inputs probably originate in western Europe.
For more detailed information on hazardous substances, see the following fact sheets:
Emissions of cadmium, mercury and lead to the air in period 1990-2001
Atmospheric depositions of cadmium, mercury and lead on the Baltic Sea in 1990-2001
Heavy metals in the Baltic Sea waters
Total amounts of the artificial radionuclide caesium -137 in Baltic Sea sediments
Concentrations of the artificial radionuclide caesium-137 in Baltic Sea fish and surface waters
Helsinki Commission
