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PCB Pollution of rivers : Onema sets up the national network to monitor fish contamination

The three ministries in charge of Ecology, Fishing and Health launched a vast action plan in the beginning of the year to reduce the pollution caused in rivers by PCBs (polychlorinated biphenyls). Onema participates in four parts of the plan. A particular responsibility is to set up and coordinate the national network to monitor fish contamination.

In June 2007, a Cemagref report revealed contamination of the Rhône by PCBs, which are chlorinated chemical derivatives, often sold as Aroclor or Pryanol and used for years in industry as lubricants and for electrical insulation. The PCB levels found in the flesh of fish in the Rhône were higher than permitted by European health standards and the French authorities immediately banned fishing and consumption of the fish. Both the manufacture and use of PCBs have been forbidden for over 20 years given the clearly recognised toxicity of the products. However, due to their persistence (non biodegradable) and low degree of solvency in water, PCBs released years ago have accumulated in soil and sediments. Even today, they continue to contaminate the food chain. In October 2007, a map showing the PCB contamination of sediments was released by the Ecology ministry and made clear that the pollution was not limited to the Rhône, but also affected two other basins, Seine-Normandie and Artois Picardie.


Onema participates in four parts of the national plan

Given the situation, the authorities set up in the beginning of 2008 an action plan targeting six main points.
The six points in the national action plan:

  • increase efforts to reduce release of PCBs to the environment,
  • improve scientific knowledge on the role of PCBs in aquatic environments and manage the pollution,
  • reinforce inspections on fish intended for human consumption and adopt any necessary risk-management measures,
  • improve knowledge on health risks and their prevention,
  • accompany commercial and recreational fishermen affected by the risk-management measures,
  • evaluate and report on plan results and progress.
Onema participates in four parts of the plan in that it supports the research on the role of PCBs in aquatic environments, it coordinates the national network to monitor fish contamination, it assists State services in accompanying fishermen affected by the risk-management measures and it participates in the national evaluation and steering committee.

Better understanding the role of PCBs in aquatic environments

Onema immediately accepted to co-finance a study launched by Cemagref. The goal of the study is to better understand the complex phenomena of PCB transfer from sediment to freshwater fish and then to develop a model to simulate transfer between the sediment and fish in order to determine a sediment-contamination threshold under which the effects on fish are acceptable. In addition, Onema is funding a study by Ifremer to draw up a summary on PCB chemical monitoring and research efforts concerning their distribution, bioaccumulation and genotoxic effects. Any detected geographical correlations between sediment and fish contamination will serve to identify zones requiring priority decontamination and those where sediment must be managed with caution.

A national network to monitor contamination of fish

To avoid consumption of any PCB-contaminated fish and enable that of healthy fish, it is above all necessary to determine where the contaminated fish are located. To that end, a national sampling program for fish in aquatic environments was launched under Onema management, in compliance with technical specifications set by AFFSA (French agency for food safety). The goal was to determine PCB levels in fish in selected geographical sites. Depending on the results, three different situations will be addressed. First, if PCB levels are below the authorised levels for all fish species, then fishing and consumption of the fish should be permitted. Second, if only certain species are contaminated, then further analysis will be required to determine whether it should be possible to consume the non-affected species. Third, if all fish species are contaminated, then all consumption will be forbidden due to the health risk.

300 sites in detail

Sediment and fish samples were drawn on a total of 300 sites. But initially, given the urgency of the situation, the work concentrated on about 100 sites considered the most risky. They were the 87 most contaminated French sites with PCB concentrations in sediment greater than 141 ng/g MS and 20 other sites, identified with the assistance of the Water agencies, that have concentrations greater than 10 ng/g and are located downstream of cities or major industrial sites, i.e. that are likely to have been polluted. The 107 selected sites are located essentially in the most affected basins, i.e. Seine-Normandie (31), Rhône-Méditerranée (31) and Artois-Picardie (28), with lesser numbers located in Loire-Bretagne (11), Rhin-Meuse (5) and Adour-Garonne (1).


Samples drawn by the local offices

Samples of fish and sediment were collected during the month of May, according to a detailed schedule established jointly by the Onema regional offices and the Water agencies. The most suitable methods were used by the Onema technicians depending on the species and the local environment, i.e. electric fishing, eel pots or nets. The technicians occasionally called on professional fishermen in places where nets could be used. The instructions were to collect, on each site, two indicator species of fish, one subject to high bioaccumulation of PCB such as eels, bream, carp or barbel, and one subject to low bioaccumulation such as roach, perch, pikeperch and dace. They gathered five batches of each species.

The fish samples will be prepared in Clermont-Ferrand, at the French meat-industry technical centre, and the analyses will be finished by the end of the year at the Laboratory on food contaminants and residues (Laberca) in the Nantes veterinary school, the national reference lab for dioxins and PCBs. At the request of the Ecology ministry and in addition to the PCB analyses, the Laberca experts will look for mercury in the samples of the eel and the carnivorous fish. The data, entered directly into a database, will be easily accessible to the various participants in the PCB programme. The cost of the overall programme to monitor fish contamination is 900 k€ for 2008, of which 50% is financed by Onema, 35% by the Agriculture and Fisheries ministry and 15% by the Health ministry.

The fish samples will be kept for five years in a "food bank" for potential later use in analysing other pollutants.

Main dates

  • June 2008. End of sampling operations for fish and sediment.
  • End of July 2008. End of sampling preparation.
  • End of 2008. Analysis results available from Laberca.
  • Beginning of 2009. Interpretation of data analysed by the French agency for food safety (AFSSA).