Monitoring Program for Pharmaceuticals, illegal substances and contaminants in farmed fish

— Annual report for 2019

Summary

This report summarises the monitoring data collected in 2019 on the status of illegal substances, pharmaceuticals and contaminants in Norwegian farmed fish. A total of 13 725 fish were collected. Samples examined for illegal compounds would be collected at all stages of farming and are representative of farmed fish under production. The samples were analysed for substances with anabolic effects or unauthorized veterinary drugs. No residues of illegal compounds were detected. Samples tested for approved veterinary drugs and contaminants were collected at processing plants and are representative of Norwegian farmed fish ready for human consumption. Residues of anti-sea-lice agents were found in five samples, the levels present were below the Maximum Residue Limit (MRL) for all samples. Other veterinary drugs, like antibiotics or drugs used against internal parasites were not found. No environmental contaminants were found above the EU maximum levels.

1 - Introduction

1.1 - Background

According to EU legislation (EU 96/23/EC), all food producing animals should be monitored for certain substances and residues thereof. The following residues or substance groups are monitored in Norwegian farmed fish:

Group A Substances with anabolic effects and unauthorized substances:

A1: Stilbenes, derivatives and their salts and esters

A3: Steroids

A6: Prohibited substances

Group B Veterinary drugs and contaminants:

B1: Antibacterial agents

B2a: Anthelmintics

B2d: Sedatives

B3a: Organochlorine compounds

B3b: Organophosphorus compounds

B3c: Chemical elements

B3d: Mycotoxins

B3e: Dyes

B3f: Others

1.2 - Group A, Substances with anabolic effects and unauthorized substances

Fish tested for illegal compounds were collected at the farm by official inspectors from the Norwegian Food Safety Authorities, without prior notification to the farmers. Samples were taken at all stages of farming in order to represent farmed fish during production. Substances monitored in Group A include growth promoters like steroids and stilbenes, and unauthorized drugs. Unauthorized drugs considered most relevant for aquaculture are chloramphenicol, nitrofurans, metronidazole and dyes. Since the use of the dyes malachite green, crystal violet and brilliant green is not allowed for food producing species (EU 37/2010), they are considered Group A substances and hence monitored in samples throughout the production chain. However, according to directive 96/23 these dyes belong to the group B3e. Thus, in order to fulfill criteria for group B sampling, some of the samples assigned to analysis of dyes were also collected at the slaughterhouse.

To ensure harmonized levels for the control of unauthorized substances, the analytical methods should meet a minimum required performance limits (MRPLs) set by the European Union (EU 2003/1881, EU 2004/25, CRL 2007), and European reference laboratories (EU-RLs), (EU 2003/1881, EU 2004/25, CRL 2007). Table 6.3 gives an overview of MRPLs of relevant compounds.

1.3 - Group B, veterinary drugs

In order to protect public health, current EU legislation (EU 37/2010) provisions the assignment of Maximum Residue Limits (MRLs) for all legally applied pharmacologically active substances in products intended for human consumption. An MRL denotes the highest permitted residual concentration of a legally applied veterinary drug and is evaluated for each substance and each food product individually. Consumption of food with drug residues below the MRL should not pose a health risk to the consumer. For fish, the MRLs are set for muscle and skin in natural proportions. Samples examined for veterinary drugs were collected from fish at processing plants and the samples are representative of fish ready to be placed on the market for human consumption.

1.4 - Group B, contaminants

Samples examined for contaminants were collected from fish at processing plants and are representative of fish ready for human consumption. The EU (EU 1881/2006) has set a maximum level (ML) for some of the contaminants in fish, while for others, like the pesticides, PAH, PFC and BFR, maximum levels have not yet been established.

1.5 - Ethoxyquin

Ethoxyquin (EQ) is a synthetic antioxidant, which has widely been used as an additive (E324) in components for animal feed for pets and livestock to preserve product quality and increase shelf live. Because of its high efficacy, EQ has also been widely used by the global fishmeal industry both as a nutritional preservative, but also to avoid oxidation and self-ignition under long-distance transport.

2 - Material and methods

2.1 - Sampling

Samples were taken on fish farms or slaughterhouses in all fish-producing regions in Norway by official inspectors from the NFSA. The sampling plan was randomised according to season and region. In 2019, the following fish species were included in the monitoring program: Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), turbot (Scophthalmus maximus), Atlantic halibut (Hippoglossus hippoglossus), and Arctic char (Salvelinus alpinus). Samples were transported to IMR in a frozen state. For most analyses, the Norwegian quality cut (NQC) was used (Johnsen, Hagen et al. 2011). However, both NQC and individual liver samples were collected for analysis of antibiotics. Samples to be used for analyses of substances with anabolic effects or unauthorized substances also included small fish from early life stages and in these cases, the whole fish except head, tail and gut were homogenised. The samples were analysed as pooled samples comprising five fish from the same cage/farm.

2.2 - Pre-treatment

Upon arrival at IMR the sample identification was anonymised for the analysts. A back-up sample was stored for all samples. Pooled samples of muscle from five fish from the same cage/farm were homogenised before analyses. Samples of liver were excised from the fish to be screened for residues of antimicrobial agents by the microbiological inhibition zone assay. Liver samples were examined individually, if residues were detected, the back-up sample of muscle was analysed by chemical methods. The maximum residue limits for veterinary drugs are set for muscle and skin in natural proportions (EU 37/2010). Therefore, according to the analytical protocol, any detection of drug residues in the muscle or liver was followed by a re-analysis of the back-up sample, consisting of muscle and skin in natural proportions, in duplicate.

2.3 - Analytical methods

The laboratory routines and most of the analytical methods are accredited in accordance with the standard ISO 17025 (Table 6.3). A summary of the analytical methods and their limit of detection (LOD) or limit of quantification (LOQ) is shown in Table 6.3. The LOD is the lowest level at which the method is able to detect the substance, while the LOQ is the lowest level for a reliable quantitative measurement. For all methods, a sample blank and a quality control sample (QC) with a known composition and concentration of target analyte are included in each series. The methods are regularly verified by participation in inter laboratory proficiency tests, or by analysing certified reference material (CRM), where such exist.

2.3.1 - Group A substances

A1, Stilbenes

Stilbenes were extracted by water and acetonitrile. Liquid-liquid extraction was used for sample clean up. The stilbenes were analysed by LC-MS/MS.

A3, Steroids

Steroids were extracted by water and acetonitrile. Liquid-liquid extraction followed by s olid phase extraction was used for sample clean up, before the samples were analysed by LC-MS/MS.

A6, Illegal veterinary drugs

Chloramphenicol

Chloramphenicol was extracted with ethyl acetate. Liquid-liquid extraction was used to purify the extract. The samples were analysed by LC-MS/MS.

Nitrofurans

The nitrofuran metabolites were extracted with aqueous hydrochloric acid and derivatized with nitrobenzaldehyde. Solid phase extraction was used for sample clean up. The analytes were determined by LC-MS/MS.

Metronidazole

Metronidazole and its metabolite hydroxymetronidazole were extracted by ethyl acetate. Solid phase extraction was used for sample clean up. The analytes were determined by LC-MS/MS

Malachite green (MG), crystal violet (CV), brilliant green (BG)

The analytes were extracted with acetonitrile and dichloromethane. Samples clean-up were performed by solid phase extraction. MG, CV, BG and the metabolites leuco malachite green (LMG) and leuco crystal violet (LCV), were determined by LC-MS/MS.

2.3.2 - Group B substances

B1, Antibacterial agents (antibiotics)

The presence of antibacterial agents was determined by a three-plate microbiological assay or by chemical analysis.

Microbiological assay

For the three-plate microbiological inhibition method, a specific bacterial strain was added to a plate containing growth agar. Small pieces of liver were placed on the plates before incubation. If the samples contained residues of antibacterial agents, the bacterial growth would be inhibited in a zone around each piece of liver tissue. Thus, a transparent zone with no bacterial growth surrounding the liver sample would indicate a positive sample. Any positive detection was verified by chemical analysis of muscle and skin.

Florfenicol, oxolinic acid, flumequine, enrofloxacin, ciprofloxacin and trimethoprim

The analytes were extracted with acetonitrile and water. The analysis was performed by LC-MS/MS.

Oxytetracyclin

The analyte was extracted with acetonitrile. Liquid-liquid extraction was used to purify the extract. Oxytetracyclin was analysed by LC-MS/MS.

B2a, Anthelmintics

Diflubenzuron, teflubenzuron, lufenuron, hexaflumuron and fluazuron 

The analytes were extracted with acetone. Solid phase extraction was used for sample clean up. The samples were analysed by LC-MS/MS (Samuelsen, Lunestad et al. 2014).

Emamectin

Emamectin was extracted with acetonitrile, and analysed by LC-MS/MS.

Ivermectin

Ivermectin was extracted with organic solvent, and the extract were purified by solid phase extraction. The samples were analysed by LC-MS/MS

Cypermethrin and deltamethrin

Cypermethrin and deltamethrin were extracted by soxhlet extraction. The extracts were purified by gel permeation chromatography. The samples were analysed by GC-MS/MS.

Fenbendazole and praziquantel

Fenbendazole and praziquantel were extracted from the sample by acetone, and analysed by LC-MS/MS.

B2d, Sedatives

Isoeugenol

Isoeugenol was analysed by GC coupled to a flame ionization detector (FID).

B3a, Organochlorine compounds

Dioxins, dl-PCBs, PCB-6 and PBDEs.

This is an adaptation to modern clean-up equipment of the US-EPAs (Environmental Protection Agency) methods No. 1613 and 1668. Separation and quantification were performed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The method measures all of the 29 compounds on the WHO list: 17 PCDD / PCDF congeners, four non-ortho substituted PCBs: PCB -77, 81, 126 and 169 and eight mono-ortho substituted PCBs: PCB-105, 114, 118, 123, 156, 157, 167 and 189 (Berntssen, Julshamn et al. 2010). The PCBs included in PCB-6, PCBs no. 28, 52, 101, 138, 153 and 180, were analysed by GC-MS/MS. The PBDEs were analysed by GC/MS in a relevant solvent fraction from the EPA clean-up procedure (Pirard, De Pauw et al. 2003).

Chlorinated pesticides

Pesticides were extracted by organic solvent, and the extract were cleaned-up by column chromatography, before the pesticides were analysed by HRGC-HRMS.

B3b, Organophosphorus compounds

Azamethiphos and dichlorvos

The analytes were extracted with acetonitrile, and analysed by LC-MS/MS.

B3c, Elements

Lead, mercury, cadmium, arsenic, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, selenium, silver, vanadium, and zinc

The sample was decomposed by acid treatment, assisted by heat and high pressure. The metals were analysed by inductively coupled plasma mass spectrometer (ICP-MS) (Julshamn, Maage et al. 2007).

Inorganic Arsenic

Inorganic arsenic was extracted by hydrochloric acid in hydrogen peroxide at 90 °C. Inorganic arsenic includes As (III) and As (V). As (III) was oxidised to As (V) during the extraction. Inorganic arsenic was separated from other arsenic compounds by anionic exchange HPLC, and detected by ICP-MS.

Methylmercury

Methylmercury was extracted by Tetramethylammonium Hydroxide. The pH was adjusted before derivatization and extraction by hexane. The samples were analysed by GC-ICP-MS.

Tributyltin

Tributyltin was extracted by acetic acid/methanol. The pH was adjusted before derivatization and extraction by hexane. The samples were analysed by GC-ICP-MS.

B3d, Mycotoxins

Enniatin and beauvericin

The mycotoxins; beauvericin, enniatin A, enniatin A1, enniatin B and enniatin B1 were extracted with acetonitrile and water. Solid phase extraction was used for sample clean up. The mycotoxins were analysed by LC-MS/MS.

B3f, Others

HBCD

HBCD was extracted by a soxhlet apparatus, using a mixture of acetone and hexane. Sulfuric acid was used for purification. The extract was further cleaned up by an alumina column. The HBCD isomers were analysed by LC-MS/MS.

TBBPA

TBBPA was extracted by a soxhlet apparatus using a mixture of acetone and hexane. Sulfuric acid was used for purification. O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) was used for derivatization. The extract was purified using column chromatography. TBBPA was analyzed by GC-MS using Electron Ionization (EI).

PFC

PFCs were extracted by methanol, the extract was purified by solid phase extraction. PFCs were analysed by LC-MS/MS.

PAH

PAHs were extracted by dichloromethane and cyclohexane using an Accelerated Solvent Extractor (ASE). The extract was purified by solid phase extraction and analysed by GC-MS/MS.

Ethoxyquin

EQ and EQDM were extracted with hexane from pooled muscle samples, after saponification in a mixture of ethanol, NaCl and NaOH. EQ and EQDM were quantified by reversed-phase high-performance liquid chromatography with fluorescence detection, using an external standard curve, as previously described by Bohne et al. (2007), with modifications described by Ørnsrud et al. (2011).


Compounds Fish Atlantic salmon Rainbow trout Atlantic halibut Arctic char Turbot
A1 Stilbenes

Zeranol

17alpha-Estradiol

17alpha-Ethinyl-estradiol

17beta-Estradiol

beta-Zearalanol

Dienestrol

Diethylstilbestrol

Estriol

Estrone

Hexestrol

830 775 50 5   
A3 Steroids

16-Hydroxystanozolol

17alpha-Boldenone

17alpha-Trenbolone

alpha-Nandrolone

Boldenone

Chlor-Testosterone

Epitestosterone

Methyl-Boldenone

Methyltestosterone

Nortestosterone

Stanozolol

Testosterone

Testosterone propionate

Trenbolone

Trenbolone-acetate

83077060   
A6 Illegal substances
Chloramphenicol 830765605  
Metronidazole 830750755  
Nitrofuran metabolites (AOZ, AMOZ, AHD, SEM) 830760655  

Malachite green *

Crystal violet

Brilliant green

835 770 60 5   
B1 Antibiotics

Oxytetracycline

Doxycycline

Chlortetracycline

Tetracycline

1051005   

Florfenicol

Flumequine

Oxolinic acid

Enrofloxacin

Ciprofloxacin

Trimethoprim

450 405 40  5  

Quinolones (liver)

Tetracyclines (liver)

Amphenicols (liver)

Sulphonamides (liver) 

16001400170525 
B2 Other veterinary drugs
Emamectin 58551570   

Cypermethrin

Deltamethrin

61055055 5 

Diflubenzuron

Teflubenzuron

Hexaflumeron

Lufenuron

56050550 5 
Fluazuron 34031525   

Ivermectin

Abamectin

Doramectin

Eprinomectin

Moxidectin

806515   

Praziquantel

Fenbendazole

50547035   

Isoeugenol

Eugenol

20018515   
B3a Organochlorine compounds
Pesticides 49545045   

Dioxin and dl-PCBs

PCB-6

425370505  
B3b Organophosphorous compounds

Azamethiphos

Dichlorvos

25023515   
B3c Chemical elements

Lead

Cadmium

Mercury

Arsenic

Cobalt

Chromium

Copper

Iron

Manganese

Molybdenum

Nickel

Selenium

Silver

Vanadium

Zinc

305260255105

Inorganic arsenic

Methylmercury

1059510   
Tributyltin 25021530  5
B3d Mycotoxins

Beauvericin

Enniatin

50046040   
B3e Dyes

Malachite green

Crystal violet

Brilliant green *

455 425 30    
B3f Others
PBDE 350 305 40 5  
HBCD and TBBPA 355 330 25    
PAH 35533515 5 
PFC 35033510 5 
Ethoxyquin 390 355 30  5  

Table 2.1. Number of fish analysed for each substance.

Some of the samples collected have been analysed by more than one method. Therefore, the total of fish in this table will be higher than the number of fish collected.

* According to directive 96/23, malachite green, crystal violet and brilliant green belongs to the group B3e. However, these dyes are not allowed to be used for food producing animals, therefore samples analysed for dyes have been collected as both group A samples (illegal drugs) and group B samples (dyes).

3 - Results

3.1 - Substances with anabolic effects and unauthorized substances

3.1.1 - Stilbenes

A total of 166 pooled samples from Atlantic salmon, rainbow trout and Atlantic halibut were examined for presence of stilbenes. None of the included stilbenes were detected in the samples analysed.

3.1.2 - Steroids

The presence of steroids was examined in 166 pooled fillet samples of Atlantic salmon and rainbow trout. None of the substances were detected in the samples analysed.

3.1.3 - Unauthorized veterinary drugs

Totally 665 pooled samples were analyzed for unauthorized veterinary drugs, including chloramphenicol, nitrofurans, metronidazole and dyes (malachite green, crystal violet, brilliant green). No residues of the included substances were detected in any of the samples.

3.2 - Veterinary drugs

Samples analysed for veterinary drugs were collected from fish at processing plants and are representative of fish ready for human consumption. The maximum residue limit for veterinary drugs is defined for muscle and skin in natural proportions (EU 37/2010). Therefore, according to the analytical protocol, any detection of drug residues in the muscle or liver would be followed by a re-analysis of the backup sample, consisting of muscle and skin in natural proportions, in duplicate.

3.2.1 - Group B1, Antibacterial agents

The antibacterial agents were determined by a combination of the three-plate bioassay and chemical methods. The broad groups a) quinolones, b) amphenicols and tetracyclines and c) sulphonamides were measured in pooled liver samples from 1600 fish. Oxytetracyclin (21 pooled samples) and florfenicol, flumequin, oxolinic acid, enrofloxacin, ciprofloxacin and trimethoprim (90 pooled samples) were also analysed by chemical methods. No residues were detected in any of the analysed samples. The LOQs of the respective compounds are listed in Table 6.3.

3.2.2 - Group B2a, Anthelmintics

The levels of the anthelmintics; teflubenzuron, diflubenzuron, hexaflumenuron, lufenuron, fluazuron, cypermethrin, deltamethrin, emamectin, ivermectin, praziquantel and fenbendazole were determined in 508 pooled muscle samples representing 2540 fish. Emamectin was detected in three out of 117 pooled samples of Atlantic salmon, at concentrations of 3, 14 and 15 µg/kg. This concentration is below the MRL of 100 µg/kg (EU 37/2010). Residues of the anti-sea-lice agent lufenuron was found in two samples of Atlantic salmon, at concentrations of 22 and 57 µg/kg, respectively. The MRL for lufenuron is 1350 µg/kg (EU 37/2010). No residues were detected for the other anthelmintics. LOQs for the substances are specified in Table. 6.3.

3.2.3 - Group B3b, Organophosphorous compounds

The levels of the B3b substances azamethiphos and dichlorvos were determined in 47 and 3 pooled fillet samples of Atlantic salmon and rainbow trout, respectively. No residues of these agents were detected in any of the examined samples.

3.2.4 - Group B3d, Sedatives

No residues of isoeugenol were detected in any of the 40 samples analysed for this sedative.


3.3 - Contaminants

Samples analysed for contaminants were collected from fish at processing plants and are representative of fish ready for human consumption.

3.3.1 - Group B3a, Organochlorine compounds

The levels of organochlorine compounds were determined in 254 pooled samples. The results are summarised in Table 3.1 to 3.3.

3.3.1.1 - Organochlorine pesticides

For several of the pesticides, the amount present is calculated as a sum including metabolites or transformation products (EU GD SANTE 2017). The results for these groups of pesticides are presented in Table 3.1. To calculate the sum of the components, conversion factors (Table 6.4) are used to adjust for different molecular weights (EU GD SANTE 2017). The sums in Table 3.1. were calculated according to the upper bound (UB) formula. When using UB calculations, the numerical value of LOQ is substituted for analytes with levels below LOQ. UB represents a “worst case scenario”. As an example, all measurements of endosulfan are below LOQ, however, a sum is generated based on the LOQ-values.

 Atlantic salmon Rainbow trout
Sum n 90 9
DDT Median (UB) 5.6 6.1
Max (UB) 2411
Endosulfan Median (UB) 0.85 0.85
Max (UB) 1.3 0.87
Aldrin and dieldrin Median (UB) 1.1 1.2
Max (UB) 4.91.9
Chlordane Median (UB) 0.87 0.83
Max (UB) 2.61.4 
Heptachlor Median (UB) 0.43 0.47
Max (UB) 1.1 0.68
Toxaphene Median (UB) 2.2 2.3
Max (UB) 6.0 4.8
Table 3.1. The sum of groups of pesticides (µg/kg w.w.) in fillets of farmed fish

 

Of the groups of pesticides calculated from a sum of several component, the highest values measured in Atlantic salmon fillet were 24 µg/kg w.w of DDT, with a contribution from mostly p,p`-DDE (15 µg/kg w.w), and 6 µg/kg w.w Toxaphene. DDT and Toxaphene were also the highest measured concentrations in rainbow trout, with 11 and 4.8 µg/kg w.w, respectively.


The results for the other pesticides are summarised in Table 3.2. Hexachlorbenzene and trans-nonachlor were present in concentrations above LOQ in most of the samples. The highest levels measured were 4.2 µg/kg w.w. hexachlorobenzene and 2.4 µg/kg w.w. of trans-nonachlor in Atlantic salmon samples. There are currently no MRLs established in fish fillet for any of the listed pesticides (EU 2014).

Pesticide Atlantic salmon Rainbow trout LOQ
 n 90 9  
α-Hexachlorocyclo-hexane #Values 11 2  
Median LOQ LOQ  
Max 0.33 0.18 0.13-0.60
β-Hexachlorocyclo-hexane #Values4 1  
Median LOQ LOQ  
Max 0.26 0.23 0.13-0.60
γ-Hexachlorocyclo-hexane #Values 2 0  
Median LOQ LOQ  
Max 0.18 LOQ 0.13-0.60
δ-Hexachlorocyclo-hexane #Values 0 0  
Median LOQ LOQ  
Max LOQ LOQ 0.13-0.60
Hexachlorobenzene #Values 89 9  
Median 1.31.3  
Max 4.2 2.4 0.06-1.0
Pentachlorobenzene #Values 12  
Median LOQ LOQ  
Max 0.65 0.46 0.30-1.2
Trans-Nonachlor #Values 89 9  
Median 0.70 0.84  
Max 2.4 1.4 0.13-0.60
Endrin #Values 2 0  
Median LOQ LOQ  
Max 0.30 LOQ 0.15-0.71
Mirex #Values 14 2  
Median LOQ LOQ  
Max 0.15 0.07 0.05-0.24
Octachlorstyrene #Values 54 7  
Median 0.09 LOQ  
Max 0.32 0.15 0.03-0.12

Table 3.2. Pesticides (µg/kg w.w.) in fillets of farmed fish.


3.3.1.2 - Dioxin, dl-PCBs and PCB-6

The levels of dioxin (PCDD+PCDF), dl-PCBs and PCB-6 in farmed fish are shown in Table 3.3. The data is mainly represented by Atlantic salmon, but also samples from rainbow trout and Atlantic halibut were examined.

The sums of dioxins, dioxins + dl-PCBs and PCB-6 are calculated as upper bound (EU 1259/2011). Accordingly, the numerical LOQ values were used for congeners with levels below LOQ.

The levels of dioxins and dl-PCBs are reported as ng toxic equivalents 2005 (TEQ05)/kg and represent the sum of 17 different PCDD/F and 12 dl-PCBs where each congener was multiplied by a Toxic Equivalency Factor (TEF). TEF values are determined by WHO, and the toxicity of each congener is expressed relative to the most toxic form of dioxin, 2,3,7,8-TCDD which has a TEF value of 1 (EU 1259/2011) .

For salmon, the median of the sum of dioxins was 0.25 ng TEQ/kg w.w. The maximum value was 0.39 ng TEQ/kg w.w., which is below the EU maximum level of 3.5 ng TEQ/kg w.w.

The median of the sum of all 29 PCDD/F and dl-PCBs was 0.54 ng TEQ/kg w.w for salmon and 0.55 ng TEQ/kg w.w for rainbow trout. The highest result for sum dioxin and dl-like PCBs was found in one Atlantic halibut sample at 1.5 ng TEQ/kg w.w. All measured values were below the EU maximum level of 6.5 ng TEQ/kg w.w.

The median of PCB-6 for salmon was 3.5 μg/kg w.w and 3.7 in rainbow trout. The concentration of PCB-6 in one Atlantic halibut sample was 13 μg/kg w.w, which was the highest concentration PCB-6 measured. The EUs maximum level for PCB-6 in fish is 75 μg/kg w.w..

 Atlantic salmon Rainbow trout Atlantic halibut Maximum level 
 n 74 10 1  
Sum dioxins (ng TEQ/kg w.w.) Median 0.25 0.26 -  
Max 0.39 0.30 0.45 3.5
Sum dioxin + dl-PCBs (ng TEQ/kg w.w.)Median 0.54 0.55 -  
Max 0.90 0.76 1.5 6.5
 Samples 74 10 1  
PCB-6 (µg/kg w.w.) Median 3.5 3.7 -  
Max 7.7 6.3 13 75

Table 3.3. Dioxins, dl-PCBs and PCB-6 in fillets of farmed fish.

 

3.3.2 - Group B3c, Chemical elements

In 2019, monitoring of the levels of chemical elements, such as arsenic (and inorganic arsenic), total mercury in addition to methylmercury, cadmium, lead and mono-, di- and tributyltin included samples of Atlantic salmon, Rainbow trout, Atlantic halibut, Atlantic char and turbot.

The EU maximum level for mercury is 0.50 mg/kg w.w. for the species analyzed in this report, except Atlantic halibut which have a EU maximum level of 1.0 mg/kg w.w. (EU 1881/2006). Total mercury levels above LOQ were found in all measured samples, with the highest concentrations of 0.07 mg/kg w.w. in rainbow trout and halibut and 0.06 mg/kg w.w. in salmon (Table 3.4). Thus, the concentrations measured in all samples were below the maximum level.

In addition to mercury, methylmercury was determined in 21 samples. The result showed that the levels of methylmercury (Table 6.1) were similar to the level of mercury in the same samples.

The concentrations of cadmium in most samples analyzed since 2002 have been lower than the LOQ. In 2019, a single sample of turbot was found to contain a cadmium concentration above the LOQ. With a level of 0.005 mg/kg w.w. in the fillet, the measured concentration was well below EUs maximum level of 0.05 mg/kg w.w. (EU 1881/2006).

Arsenic is determined as “total arsenic”, comprising the sum of all arsenic species. The median level of total arsenic in Atlantic salmon was 0.58 mg/kg w.w., and the highest concentration measured was 2.1 mg/kg w.w. (Table 3.4). As in the previous year, none of the samples had concentrations of inorganic arsenic above the LOQ (Table 6.1), indicating that arsenic in fish is present mainly as organo-arsenic compounds of low toxicity (Shiomi 1994). There is currently no EU upper limit for neither total arsenic nor inorganic arsenic in fish fillets.

The EU maximum level for lead in muscle meat of fish is currently set at 0.30 mg/kg w.w. (EU 1881/2006). Of the 61 pooled samples analyzed, a lead concentration above LOQ was found in a single salmon sample. The measured concentration was 0.023 mg/kg w.w., and thus well below the EU-level.

In 2019, the concentrations of 11 additional chemical elements were included into the surveillance. Silver or molybdenum was not detected in any of the analysed samples (Table 3.4). Cobalt and nickel above LOQ were found in one and four of the salmon samples, respectively, with maximum concentrations of 0.023 mg cobalt/kg fillet and 0.71 mg nickel/kg fillet. Chromium was detected in less than 50% of the samples and had a maximum concentration of 1.7 mg/kg in salmon. Copper, iron, manganese, selenium, vanadium and zinc were found at levels above LOQ in almost all samples. With the exception of zinc, where the maximum concentration of 9 mg/kg was measured in one sample of turbot, the maximum concentrations of both copper, iron, manganese, selenium and vanadium were found in salmon, and were 0.7 mg/kg, 11 mg/kg, 0.27 mg/kg, 0.35 mg/kg and 0.029 mg/kg, respectively. There is currently no EU-limit established for any of the newly included elements.

Mono-, di- and tributyltin was monitored in a total of 50 samples. The monitoring included mostly salmon samples, but also rainbow trout and turbot fillet were analyzed. There is currently no EU upper limit for tin in fish fillet. Mono- and dibutyltin were detected in 31 and 39 of the 50 samples, respectively. However, none of the samples contained mono- or dibutyltin levels above the LOQ. Tributyltin was detected in 41 of the analyzed samples. A total of 15 samples contained tributyltin above the LOQ, with the highest measured level of 0.3 µg/kg w.w. found in both rainbow trout and turbot.


Element  Atlantic salmon Rainbow trout Atlantic halibut Arctic char Turbot LOQ Maximum level
 n 52 5 1 2 1   
Mercury (mg/kg w.w.) #Values 52 5 1 2 1   
Median 0.02 0.05 LOQ LOQ LOQ   
Max 0.06 0.07 0.07 0.05 0.05 0.002 0.50
Arsenic (mg/kg w.w.) #Values 52 5 1 2 1   
Median 0.58 1.3 LOQ LOQ LOQ   
Max 2.1 2.0 2.3 2.3 2.2 0.003 n.a.
Cadmium (mg/kg w.w.) #Values 0 0 0 0 1   
Median - - - - LOQ   
Max LOQ LOQ LOQ LOQ 0.005 0.001-0.002 0.05
Lead (mg/kg w.w.) #Values 1 0 0 0 0   
Median LOQ - - - -   
Max 0.023 LOQ LOQ LOQ LOQ 0.006-0.01 0.30
Cobalt (mg/kg w.w.) #Values 1 0 0 0 0   
Median LOQ - - - -   
Max 0.023 LOQ LOQ LOQ LOQ 0.006-0.009 n.a.
Chromium (mg/kg w.w.) #Values 20 2 1 1 1   
Median LOQ LOQ LOQ LOQ LOQ   
Max 1.7 0.035 0.009 0.058 0.009 0.006-0.01 n.a.
Copper (mg/kg w.w.) #Values 52 5 1 2 1   
Median 0.4 0.4 LOQ LOQ LOQ   
Max 0.7 0.4 0.2 0.4 0.2 0.1 n.a.
Iron (mg/kg w.w.) #Values 52 5 1 2 1   
Median 2.8 2.9 LOQ LOQ LOQ   
Max 11 3.5 0.85 2.1 0.79 0.1 n.a.
Manganese (mg/kg w.w.) #Values 52 5 1 2 1   
Median 0.077 0.078 LOQ LOQ LOQ   
Max 0.27 0.081 0.099 0.061 0.55 0.03 n.a.
Molybdenum (mg/kg w.w.) #Values 0 0 0 0 0   
Median - - - - -   
Max LOQ LOQ LOQ LOQ LOQ 0.01-0.4 n.a.
Nickel (mg/kg w.w.) #Values 4 0 0 0 0   
Median LOQ - - - -   
Max 0.71 LOQ LOQ LOQ LOQ 0.07-0.1 n.a.
Selenium (mg/kg w.w.) #Values 52 5 1 2 1   
Median 0.16 0.23 LOQ LOQ LOQ   
Max 0.35 0.27 0.26 0.18 0.2 0.01 n.a.
Silver (mg/kg w.w.) #Values 0 0 0 0 0   
Median - - - - -   
Max LOQ LOQ LOQ LOQ LOQ 0.002-0.004 n.a.
Vanadium (mg/kg w.w.) #Values 50 2 0 2 0   
Median 0.007 LOQ - LOQ -   
Max 0.029 0.012 LOQ 0.003 LOQ 0.001-0.002 n.a.
Zinc (mg/kg w.w.) #Values 52 5 1 2 1   
Median 3.9 3.5 LOQ LOQ LOQ   
Max 6.8 3.9 3.7 4.2 9 0.5 n.a.
 n 43 6   1   

Monobutyltin

(µg Sn/kg w.w.)

#Values 0 0   0   
Median - -   -   
Max LOQ LOQ   LOQ 0.4-1 n.a.

Dibutyltin

(µg Sn/kg w.w.)

#Values 0 0   0   
Median - -   -   
Max LOQ LOQ   LOQ 0.2-0.5 n.a.

Tributyltin

(µg Sn/kg w.w.)

#Values 9 5   1   
Median LOQ 0.1   LOQ   
Max 0.1 0.3   0.3 0.06-0.09 n.a.

Table 3.4. Chemical elements in fillets of farmed fish.

 

3.3.3 - Group B3d, Mycotoxins

The mycotoxins enniatin A, enniatin A1, enniatin B, enniatin B1 and beauvericin were measured in 92 pooled samples of salmon and 8 pooled samples of rainbow trout. No residues of these mycotoxins were detected in any of the samples.

3.3.4 - Group B3e, Dyes

In addition to 167 samples analysed for residues of dyes as group A (illegal drugs) samples, dyes were measured in 91 pooled group B (contaminants, dyes) samples. No residues of malachite green, crystal violet and brilliant green were detected in any of the group B samples.

3.3.5 - Group B3f, others

The group B3f, others is a group not required for finfish products by the directive 96/23/EC, but are deemed relevant for analyses in Norwegian aquaculture by the NFSA (Mattilsynet) and IMR, because these undesirable compounds are present in the environment and may affect food safety. This group currently consist of brominated flame retardants (BFR), perfluorinated compounds (PFC), polyaromatic hydrocarbons (PAHs), and since 2018 also the technological feed additive ethoxyquin (EQ) and its main transformation product ethoxyquin dimer (EQDM).

3.3.5.1 - Brominated flame retardants

PBDE, TBBPA and HBCD are compounds previously used as flame retardants and widely spread in the environment. The summarised PBDE-7 (28, 47, 99, 100, 153, 154, 183) and in addition PBDE 66, 119 and 138 are shown in Table 3.5. The highest level of PBDE-7 was found in a sample of Atlantic halibut. Median values of PBDE-7 were 0.36 μg/kg w.w. and 0.33 μg/kg w.w for salmon and rainbow trout, respectively. Of 66 pooled Atlantic salmon samples and five pooled rainbow trout samples, TBBPA concentrations were detected and quantified in three samples of salmon. The highest measured TBBPA value was 0.12 μg/kg w.w.. HBCD was analysed in 66 salmon fillet samples and five rainbow trout fillet samples. Median values for salmon and rainbow trout were 0.13 and 0.09 μg/kg w.w., respectively, with the highest concentration of 0.32 μg/kg w.w. found in salmon. There are currently no EU maximum levels for BFRs in food.

 Atlantic salmonRainbow troutAtlantic halibutLOQ
 n618 1 
UB-Sum PBDE 7 Median0.360.33- 
Max0.830.561.2 
PBDE 66#Values6181 
Median0.0080.007- 
Max0.0200.0090.0280.002-0.01
PBDE 119#Values2121 
MedianLOQ-- 
Max0.0070.0030.0090.002-0.01
PBDE 138#Values000 
Median--- 
MaxLOQLOQLOQ0.003-0.02
 n6650 
TBBPA #Values30  
MedianLOQ-  
Max0.12LOQ 0.03-0.14
 n6650 
UB-Sum HBCD (α,β,γ)Median0.130.09  
Max0.320.19  

Table 3.5 . BFR (µg/kg w.w.) in fillets of farmed fish.

 
3.3.5.2 - Perfluorinated compounds

A total of 70 samples were analysed for the PFCs. All results were below the LOQ (Table 6.3). EU has currently no maximum level for PFC in fish.

3.3.5.3 - Polycyclic aromatic hydrocarbons

PAH was analysed in 71 samples, of which 67 samples were from salmon, three from rainbow trout and one from Arctic char. The results for PAH are summarised in Table 3.6. There is no maximum level for PAH in fresh fish (EU 835/2011).


PAH Atlantic salmon Rainbow trout Arctic char LOQ
 n 67 3 1  
5-methylchrysene #Values 0 0 0 0.09 - 0.13
Max LOQ LOQ LOQ  
Benz(a)anthracene #Values 6 0 0 0.09 - 0.13
Max 0.6 LOQ LOQ  
Benzo(a)pyrene #Values 2 0 0 0.09 - 0.13
Max 0.5 LOQ LOQ  
Benzo(b)fluoranthene #Values 3 0 0 0.09 - 0.13
Max 0.5 LOQ LOQ  
Benzo(c)fluorine #Values 1 1 0 0.09 - 0.13
Max 0.1 0.7 LOQ  
Benzo(ghi)perylene #Values 3 0 0 0.09 - 0.13
Max 0.5 LOQ LOQ  
Benzo(j)fluoranthene #Values 0 0 0 0.09 - 0.13
Max LOQ LOQ LOQ  
Benzo(k)fluoranthene #Values 0 0 0 0.09 - 0.13
Max LOQ LOQ LOQ  
Chrysene #Values 11 0 0 0.09 - 0.13
Max 0.8 LOQ LOQ  
Cyclopenta(cd)pyrene #Values 5 0 0 0.09 - 0.13
Max 0.5 LOQ LOQ  
Dibenz(ah)anthracene #Values 0 0 0 0.09 - 0.13
Max LOQ LOQ LOQ  
Dibenzo(a,e)pyrene #Values 0 0 0 0.44 – 0.66
Max LOQ LOQ LOQ  
Dibenzo(a,h)pyrene #Values 0 0 0 0.44 – 0.66
Max LOQ LOQ LOQ  
Dibenzo(a,i)pyrene #Values 0 0 0 0.44 – 0.66
Max LOQ LOQ LOQ  
Dibenzo(a,l)pyrene #Values 0 0 0 0.44 – 0.66
Max LOQ LOQ LOQ  
Indeno(1,2,3,-cd)pyrene #Values 1 0 0 0.09 - 0.13
Max 0.3 LOQ LOQ  

Table 3.6. PAH (µg/kg w.w.) in fillets of farmed fish.


3.3.5.4 - Ethoxyquin

EQ and EQDM levels were measured in 78 pooled fillet samples. The samples were mostly taken from Atlantic salmon, but also samples from rainbow trout and Atlantic char were included (Table 3.7). The fillet concentrations of EQ and EQDM were calculated as upper bound (UB), using the numerical LOQ values (0.001 and 0.005 mg/kg ww, respectively) for measurements below LOQ. The number of samples with measurements above LOQ is indicated in Table 3.7 as the number of values.

For salmon samples, the median level of the sum of EQ & EQDM was 0.02 mg/ kg ww. Rainbow trout contained sum EQ & EQDM at a median concentration of 0.016 mg/kg ww. One sample of Atlantic char was analysed, which did not contain levels above the LOQ.

The maximum values of EQ and EQDM were 0.02 and 0.35 mg/kg ww, respectively, and were found in salmon. 

 Atlantic salmon Rainbow trout Atlantic char LOQ
 n 71 6 1  
EQ (mg/kg ww) #Values 19 2 0  
Median LOQ - -  
Max 0.02 0.004 LOQ 0.001
EQDM (mg/kg ww) #Values 62 6 0  
Median 0.02 0.02 -  
Max 0.35 0.18 LOQ 0.005
Sum EQ&EQDM (mg/kg ww) UB     
Median 0.02 0.02 -  
Max 0.36 0.18 0.006  

Table 3.7. Ethoxyquin and ethoxyquin dimer in fillets of farmed fish.

4 - Discussion

4.1 - Unauthorized substances

No residues of unauthorized substances were detected in any of the analysed samples.

4.2 - Veterinary drugs

Most samples reviewed in this report are from fillets of farmed fish. However, as the liver has a central function in the distribution and elimination of veterinary drugs, liver samples were analysed for antibiotics. Even though the bioassay used for the antibacterial agents is less sensitive than the chemical analytical methods, the higher concentrations of antibacterial agents in liver compared to fillet enhance the ability to detect any residues. Moreover, the ability of the bioassay to detect a wider range of antibiotics than the more specific chemical methods renders the method useful for screening purposes. Any positive detection by the inhibition assay is verified by chemical analysis of the corresponding fillet sampled from the same fish. Consistent with the data gathered in the monitoring of recent years, no residues of antibiotics, endoparasitic agents or dyes were detected in any of the samples.

In 2019, residues of the anti-sea-lice agents emamectin and lufenuron were detected in three and two samples of Atlantic salmon, respectively. However, the rate of positive samples is low and the concentrations are well below the MRLs for both emamectin and lufenuron.

No residues of antibiotics, endoparasitic agents or sedatives were detected in any samples taken during 2019.

4.3 - Contaminants

Although the level of dioxins and dl-PCBs decreased from 2006 until 2012, reflecting the increased substitution of marine ingredients with vegetable ingredients in the feed, the level appears to have stabilized at approximately 0.5 ng TEQ/kg w.w. in farmed Atlantic salmon. This level has been rather stable from 2012 up to, and including, 2019.

As in the previous year, in 2019 no environmental contaminants were found above the EU maximum levels (MLs), for those contaminants where MLs have been implemented. However, the EUs MLs for food are not based on toxicological data, but derived from the ALARA (as low as reasonably achievable) principle, with the aim to prevent those commodities with the highest contaminant levels to reach the market. For all contaminants included in the programme, including brominated flame retardants (PBDEs, HBCDs and TBBP), PAHs, PCB-6 and pesticides, the concentrations were comparable to the years before.

Starting in 2019, in addition to the four heavy metals (Hg, As, Pb and Cd) traditionally included, the surveillance of chemical elements in fish fillet was extended with 11 other elements: cobalt, chromium, copper, iron, manganese, molybdenum, nickel, silver, selenium vanadium and zinc. There are currently no MLs established for any of the added elements in fish.

The levels of DDT were comparable to the years before.

4.4 - Ethoxyquin

Following the suspended authorization of the use of ethoxyquin as an anti-oxidant feed additive (EU 2017/962), specific transitional measures were settled for compound feed produced with mostly marine-derived feed material containing ethoxyquin and premixtures containing ethoxyquin (Article 3, EU 2017/962) due to a lack of suitable alternatives. These compound feeds were permitted to be placed on the marked until 31.03.2020 and used no longer than three months after this date.

The implementation of the regulation by the industry is clearly reflected the by decrease in fillet concentration of both ethoxyquin and its main transformation product the ethoxyquin dimer. In 2018, ethoxyquin and ethoxyquin dimer were found above LOQ in 61 and 99% of the analysed salmon fillet samples, respectively. In 2019, only 27% and 87% of the sampled salmon fillets had levels of ethoxyquin and ethoxyquin dimer, respectively, above LOQ. In addition, median values declined from 0.002 and 0.11 mg/kg ww to LOQ (0.001 mg/kg ww) and 0.002 mg/kg ww for EQ and EQDM, respectively.

Due to limited data on toxicity of EQ and its metabolites, a precautional maximum residue level (MRL) at the limit of analytical quantification (0.05 mg/kg), is currently applied in the EU (EU 2014). The list of products where a MRL has been established includes several products of animal origin. The median concentration of the sum EQ & EQDM does not exceed the currently set precautional MRL value. However, no MRL has yet been defined for fish.

5 - Conclusion

No substances with anabolic effect were detected in any of the samples analysed.

None of the veterinary drugs were detected at levels exceeding the MRL established for fish. Emamectin or lufenuron were detected in a total of five samples, but the measured levels were below their respective MRLs.

For contaminants, no samples exceeded the EUs maximum levels, where such levels have been established (sum dioxins, sum dioxins and dl-PCBs, PCB-6, mercury, lead and cadmium).

6 - Tables

  Atlantic salmon Rainbow trout LOQ
 n 19 2  
Inorganic arsenic (µg/kg w.w.) #Values 0 0  
Median - -  
Max LOQ LOQ 2-3
Methyl-mercury (mg Hg/kg w.w.) #Values 19 2  
Median 0.02 -  
Max 0.05 0.03 0.001

Table 6.1. Inorganic arsenic and methylmercury in fillets of farmed fish

CompoundAtlantic salmonRainbow troutArctic charMax valueLOQ
PFBA 6721<LOQ1.0
PFBS 1.0
PFDA 0.2
PFDoDA 0.2
PFDS 0.2
PFHpA 0.2
PFHxA 0.5
PFHxS 1.0
PFNA 0.2
PFOA 0.6
PFOS 0.2
PFOSA 0.5
PFTeDA 0.2
PFTrDA 0.2
PFUdA 0.2

 

 

Table 6.2. PFCs (µg/kg w.w.) in fillets of farmed fish

Group of substances Analyte Method LOD (µg/kg w.w.) LOQ (µg/kg w.w.) Level of action (µg/kg w.w.) Laboratory
A1 StilbenesDiethylstilbestrolLC-MS/MS 1  Presence Eurofins
Dienestrol1
Hexestrol1
Β-Estradiol1
α-Estradiol1
Estriol1
Estrone1
Ethinyl estradiol1
A3 Steroidsα-nandrolonLC-MS/MS 1  Presence Eurofins
β-nandrolon1
α-trenbolon1
β-trenbolon1
Trenbolone-acetate2
16-Hydroxy stanozolol1
α -Boldenone1
Boldenone1
Chlor-Testosterone (Clostebol)1
Epitestosterone1
Methyl-Boldenone (Dianabol)1
Methyltestosterone1
Nortestosterone/ Nandrolone1
Stanozolol1
Testosterone1
Testosterone-propionate2
A6 Annex IV substancesChloramphenicolLC-MS/MS 0.25  Presence (MRPL = 0.3) IMR
MetronidazoleLC-MS/MS 0.3  Presence (MRPL = 3.0)
Hydroxy-metronidazole2.0  
Nitrofuran AOZLC-MS/MS 0.5  Presence (MRPL =1.0)
Nitrofuran AHD0.6  Presence (MRPL =1.0)
Nitrofuran AMOZ0.4  Presence (MRPL =1.0)
Nitrofuran SEM 0.5  Presence (MRPL= 1.0)
B1 Antibacterial Substances Micro-biological method Quinolones3-plate Screening Method2 200  100-600 IMR
Tetracyclines 200  100
Amphenicols 200  1000
Sulfonamides 400  100
B1 Antibacterial substances Chemical method Oxolinic acid LC-MS/MS  40 100 IMR
Flumequine 40 600
Enrofloxacin 10 100
Ciprofloxacin 10 100
Trimethoprim 2 50
Oxytetracycline LC-MS/MS  30 100 Eurofins
Florfenicol LC-MS/MS  0.5 1000 IMR
B2a Anthelmintics Praziquantel LC-MS/MS  1 n.a. IMR/ Eurofins
Fenbendazole LC-MS/MS  1 n.a.
Emamectin LC-MS/MS  2-10 100
Diflubenzuron LC-MS/M  1-10 10
Teflubenzuron 1-50 500
Hexaflumuron 1-50 500
Lufenuron 1-50 1350
Ivermectin LC-MS/M 2 n.a. Eurofins
Cypermethrin GC-MS  5 50
Deltamethrin 10 10
Isoeugenol GC-FID  50 6000
B3a Organo-chlorine compounds Dioxins and dlPCB HRGC-HRMS  0.0001-0.1 ng TEQ/kg 6.5 ng TEQ/kg IMR
PCB-6 GC-MS GC-MS/MS  0.004 – 0.5 75
Pesticides HRGC-HRMS  0.003-0.8 n.a. Eurofins
B3b Organo-phosphorus compounds Azametiphos LC-MS/MS  10 n.a. Eurofins
Dichlorvos
B3c Chemical elements Lead ICP-MS  0.005- 0.01 mg/kg 0.3 mg/kg IMR
Cadmium  0.001- 0.002 mg/kg 0.05 mg/kg.
Arsenic  0.003 mg/kg n.a.
Mercury  0.002 mg/kg 0.5 mg/kg
Cobalt  0.006-0.009 mg/kgn.a.
Chromium  0.006- 0.01 mg/kgn.a.
Copper  0.1 mg/kgn.a.
Iron  0.1 mg/kgn.a.
Manganese  0.03 mg/kgn.a.
Molybdenum  0.01- 0.4 mg/kgn.a.
Nickel  0.07- 0.1 mg/kgn.a.
Selenium  0.01 mg/kgn.a.
Silver  0.002- 0.004 mg/kgn.a.
Vanadium   0.001- 0.002 mg/kgn.a.
Zinc  0.5 mg/kgn.a.
Inorganic arsenic LC-ICP-MS  4-6 n.a.
Methylmercury GC-ICP-MS  1 n.a.
Tributyltin GC-ICP-MS  0.3-0.5 n.a.
B3d Mycotoxins Beauvericin, Enniatin A, A1, B and B1 LC-MS/MS  10 n.a. Eurofins
B3e, dyes Malachite green LC-MS/MS 0.15  Presence (MRPL=2) IMR
Leuco malachite green 0.15  
Crystal violet 0.30  Presence
Leuco crystal violet 0.15  Presence
Brilliant green 0.15  Presence
B3f, others PBDE GC-MS  0.003-0.009 n.a. IMR
HBCD LC-MS/MS  0.006-0.01 n.a. Eurofins
TBBPA GC-MS  0.03-0.2 n.a. Eurofins
PAH GC-MS/MS  0.5-1.0 n.a. IMR
PFC LC-MS/MS  0.5-13 n.a. IMR
Ethoxyquin HPLC-FLD  0.001 n.a. IMR
Ethoxyquin dimer 0.005 n.a.
1 All methods used muscle as sample matrix except for microbiological methods for antibacterial substances (B1), were liver was used 2 Only screening method, positive results have to be confirmed by a chemical method.

Table 6.3. Summary of analytical methods.

SumSubstances included in the sum Conversion factor
DDT ( sum of p,p-DDT, o,p-DDT, p,p-DDD, o,p-DDD, p,p-DDE,and o,p-DDE expressed as DDT) op-DDT1
pp-DDT1
op-DDD1.108
pp-DDD1.108
op-DDE1.115
pp-DDE1.115
Endosulfan (sum of alpha- and beta-isomers and endosulfan-sulphate expressed as endosulfan) alpha-endosulfan1
beta-endosulfan1
endosulfan sulphate0.962
Aldrin and dieldrin (Aldrin and dieldrin combined expressed as dieldrin) dieldrin1
aldrin1.044
Chlordane (Sum of cis- and trans-isomers and oxychlordane expressed as chlordane) trans-chlordane1
cis-chlordane1
oxychlordane0.967
Heptachlor ( sum of heptachlor and heptachlor epoxide expressed as heptachlor) heptachlor1
trans-heptachlor epoxide0.959
cis-heptachlor epoxide0.959
Toxaphene ( sum of toxaphene 26, toxaphene 50 and toxaphene 62) Toxaphene 261
Toxaphene 501
Toxaphene 621

Table 6.4. Calculation of sums for certain pesticides.

7 - References

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