Endosulfan in feed and farmed Atlantic salmon

The annual monitoring program on substances and residues in farmed fish conducted by NIFES for the Norwegian Food Safety Authority showed that farmed salmon contains very low levels of the pesticide endosulfan.
September 10, 2015

Pesticides are used in farming to increase food production. Between 1995 and 2007 about 2.3-2.6 million tons of pesticides were used globally, consequently it is unavoidable that feed and food contain residues. Endosulfan is a pesticide used on rice and maize but is on the Stockholm Conventions list of persistent organic pollutants and its use is being phased out. Endosulfan is a pesticide currently not authorized in the European Union and is regulated as an undesirable substance in animal feed. Endosulfan is still used in some parts of the world that export food and feed ingredients to Europe. Maximum Residue Levels (MRLs) have been established to limit the residues in food in order to protect consumers’ health.

Endosulfan in feed
The EU maximum limit for endosulfan in animal feed is 0.1 mg/kg while the maximum limit in fish feed is 0.05 mg/kg (EC 744/2012). Norway has implemented the same maximum limit for endosulfan in feed as that in the EU.

The former maximum limit for endosulfan in feed was even lower: 0.005 mg/kg. This was set based on a lack of scientific documentation on the effects of endosulfan in fish feed, hence the European Food Safety Authority (EFSA) recommended that studies on carry-over, accumulation and oral toxicity should be performed in farmed fish. Several feeding trials were conducted by NIFES on the effects of endosulfan in Atlantic salmon between 2006-2010. The results showed that endosulfan in feed up to 0.1 mg endosulfan/kg had low toxicity in salmon. Histological changes were observed in the intestine in Atlantic salmon following exposure to 0.005 mg endosulfan/kg in feed in fresh water, without a clear dose-effect relationship. Such changes in the intestine were not seen when Atlantic salmon were exposed to up to 0.1 mg endosulfan/kg feed in seawater. These studies were assessed by EFSA in 2011. The maximum limit for endosulfan in Salmonid feed was increased from 0.005 mg/kg to 0.05 mg/kg based on EFSA’s statement (Commission Regulation No 744/2012). The Commission supported this increase on the following: \"EFSA stated that no significant adverse effects were observed in fish (Atlantic salmon) exposed to 0.1 mg/kg endosulfan in feed”. Furthermore the Commission stated: \"It is appropriate to propose a higher maximum level for endosulfan in complete feed for Salmonids to favour the evolution for increased sustainability of the fish farming without resulting in adverse effects for fish health and human health”.

Fish feed contained between 0.0006 and 0.001 mg endosulfan/kg in the last nine years and in 2013 the average content was 0.0008 mg/kg (Annual monitoring program for 2014 conducted by NIFES for the Norwegian Food Safety Authority).

Endosulfan in salmon fillets
There is no MRL for endosulfan in salmon fillet in Europe. The MRL for endosulfan in meat is 0.1 mg/kg. Data from the annual monitoring program on certain substances and residues in farmed fish conducted by NIFES for the Norwegian Food Safety Authority, in accordance with Council Directive 96/23/EC showed that in 2014 farmed Norwegian salmon contained between 0.00006 and 0.0025 mg/kg (minimum-maximum) with an average level of 0.00014 mg/kg.

The Acceptable Daily Intake (ADI) is the amount of an additive or a pesticide residue in food that a person can ingest daily without an appreciable health risk. The Joint FAO/WHO Meeting on Pesticide Residues established an ADI of 0.006 mg per kg body weight per day for endosulfan in 1998. Eating 300 g salmon with the highest concentration measured (0.0025 mg/kg) accounts for approximately 0.2% of the ADI for a 70 kg person. Hence farmed salmon is a negligible source of endosulfan.