Non-dioxin like PCB contaminant levels decreasing in food and animal feed - continuing effort needed to further reduce possible risks to human health
The Panel on contaminants in the food chain (CONTAM) of the European Food Safety Authority (EFSA) has published an Opinion on non-dioxin-like polychlorinated biphenyls (NDL-PCBs) in food and feed. Polychlorinated biphenyls (PCBs) are a mixture of individual chemicals, which, based on their biochemical and toxicological properties, can be divided into two different groups: the dioxin-like PCBs (DL-PCBs) and the non-dioxin-like PCBs (NDL-PCBs). Over 90% of human exposure to NDL-PCBs is through food. Although levels of NDL-PCBs in food have gradually decreased since environmental legislation on use and disposal of PCBs was introduced by the European Union (EU) in the 1980s, human exposure to NDL-PCBs is still considered to be high. Therefore, EFSA’s CONTAM Panel concluded in its Opinion that there should be a continuing effort to lower the levels of NDL-PCBs found in food and feed.
Following risk assessments carried out by previous EC Scientific Committees* on the presence of dioxins and dioxin-like PCBs in the food and animal feed chain, EFSA’s CONTAM Panel was asked by the European Commission to carry out an assessment of NDL-PCBs in the food and feed chain. Although the production and use of PCBs** have been discontinued in most countries since the 1980s, large amounts remain in electrical equipment, plastic products, and building materials. Due to their persistence in the environment, PCBs released in the past can still be found today. NDL-PCBs and DL-PCBs accumulate together along the food chain; they are stored in fat tissue and take a long time to leave the body. As a result, compared to fruits and vegetables, higher concentrations are found in food of animal origin, particularly in carnivores and predatory fish. NDL-PCBs generally build up in the human body primarily in fat tissue through food consumption (which accounts for 90 % of human exposure). NDL-PCBs also tend to be present at significant levels in breast milk. Levels of NDL-PCBs found in food and also in breast milk have been declining over the last decades mainly due to the effect of environmental measures introduced in the 1980s prohibiting their use in newly manufactured products.
The Panel concluded that NDL-PCBs are neither genotoxic nor carcinogenic. Various adverse effects have been associated with PCB exposure, such as neurological and developmental disorders and immune deficiencies. However, such effects are also induced by the much more potent dioxin-like compounds and it is therefore difficult to determine the precise contribution of NDL-PCB exposure.
The average daily intake of total NDL-PCBs for adults in Europe is estimated to be between 10 and 45 ng/kg b.w. (nanograms per kilogram body weight), with higher intakes observed amongst young children. Higher exposures may occur in certain groups, which are exposed to highly contaminated food, such as Baltic Sea fishermen. The estimated NDL-PCB intake of breast-fed infants could be up to two orders of magnitude higher than that of adults. However, since the benefits of breastfeeding still outweigh the possible effects of NDL-PCBs in infants, EFSA recommends that there should be no change to existing recommendations which support breast feeding.
Dr. Josef Schlatter, Chair of the CONTAM Panel, said that “the current human lifetime dietary exposure is still considerable and the long-term health effects of NDL-PCBs, particularly for highly exposed and vulnerable groups, are difficult to assess. The Panel therefore concluded that there should be a continuing effort to lower levels of NDL-PCBs in food and feed.”
The toxicity of dioxin-like PCBs (DL-PCBs) is much higher than that of NDL-PCBs and is therefore, considered to be of greater concern to food safety. NDL-PCBs co-exist with DL-PCBs and this makes it difficult to determine the true toxicological effects of NDL-PCBs alone, as the results of toxicity tests might be influenced even by the presence of the smallest amounts (0.1 % or less) of DL-PCBs. Therefore caution should be exercised in interpreting data on NDL-PCB exposure.
While current EU legislation, which sets maximum levels for other Persistent Organic Pollutants in food (such as dioxins and DL-PCBs), contributes to the overall reduction of NDL-PCBs in food, the Panel concluded that there should be a specific effort to lower the levels of NDL-PCBs in food by continuing to control their release into the environment.