Safety and efficacy of a feed additive consisting of copper lysinate sulfate for all animal species (Phytobiotics Futterzusatzstoffe GmbH)

TL;DR

This paper evaluates copper lysinate sulfate as a feed additive, finding it safe for animals and the environment but unable to confirm its safety for consumers or efficacy due to lack of data.

Contribution

The study provides a comprehensive safety assessment of copper lysinate sulfate for animal feed under EU regulatory conditions.

Findings

Copper lysinate sulfate is safe for all animal species at maximum authorized copper levels in feed.

The additive is not a skin irritant but is considered a skin and respiratory sensitiser.

The use of the additive is considered safe for the environment under proposed conditions.

Abstract

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of copper lysinate sulfate as nutritional feed additive for all animal species. The additive has not yet been authorised in the EU. The FEEDAP Panel concluded that the additive copper lysinate sulfate is safe for all animal species and categories at the respective maximum authorised total copper levels in feed. In the absence of reliable deposition data, the FEEDAP Panel could not conclude on the safety of the additive for the consumer. In the absence of data, the FEEDAP Panel could not conclude on the eye irritation potential of the additive. The Panel concluded that the additive is not a skin irritant and thus it should be considered a skin and respiratory sensitiser; inhalation and dermal exposure are considered a risk. The FEEDAP Panel concluded that the use of the additive under the proposed conditions of use is safe for the environment. The Panel was not in the position to conclude on the efficacy of the additive at the maximum authorised inclusion level.

Tables

TABLE 1. Data on the batch‐to‐batch variation and impurities of copper lysinate sulfate.

Parameter	Specification	Analysis
		Average	Range	# batches
Batch‐to‐batch variation
Copper (%, as is)	≥ 18	18.2	17.5–18.6	5
Lysine (%, as is)	≥ 40	41.6	40.8–42.2	5
Moisture (%, as is)	≤ 10	5.9	5.4–6.8	5
Sulfate (%, as is, calculated value)		29.7	28.7–30.6	5
Impurities
Lead (mg/kg)			10.3–10.8	3
Mercury (mg/kg)			< 0.03	3
Cadmium (mg/kg)			0.31–0.42	3
Arsenic (mg/kg)			< 0.5	3
Fluorine (mg/kg)			< 40	3
Nickel (mg/kg)			5.4–6.4	3
Dioxins and furans (upper bound) (1)
PCDD/Fs (ng WHO2005‐TEQ/kg)			0.9	3
PCDD/Fs + PCBs (ng WHO2005‐TEQ/kg)			0.12	3
Non DL‐PCBs (μg/kg)			1.7	3
Mycotoxins
Aflatoxin B1 (μg/kg)			< 0.3	3
Microbial contamination
Salmonella spp. (per 25 g)			Not detected	3
Escherichia coli (per 1g)			Not detected	3
Aerobic mesophilic bacteria (CFU/g)			■■■■■	■■■■■
Moulds (CFU/g)			■■■■■	■■■■■
Yeasts (CFU/g)			■■■■■	■■■■■
Enterobacteriaceae (CFU/g)			■■■■■	■■■■■

TABLE 2. Physical properties of copper lysinate sulfate.

Parameter	Analysis
	Range	# batches
Physical properties
Physical form	Solid/granules
Solubility in water (g/L; 20°C)	2050	1
Dusting potential (Stauber‐Heubach) (mg/m3)	90–125	3
Cu content in dust (mg/kg)	125,756–159,500	3
Particle size of the dust (laser diffraction) (% of particles below, v/v)
50 μm	100–100	2
10 μm	32–37	2
Particle size distribution (laser diffraction) (% of particles below, v/v)
100 μm	0.95–1.64	3
50 μm	0.42–0.58	3
10 μm	0.25–0.29	3
Homogeneity (coefficient of variation, %)
Complete feed starter (average of 10 subsamples)	27
Complete feed grower (average of 10 subsamples)	39

TABLE 3. Maximum authorised total copper content.

Animal species/categories	Maximum authorised total copper content (mg/kg complete feed)
Bovines before the start of rumination	15
Other bovines	30
Ovines	15
Caprines	35
Suckling and weaned piglets up to 4 weeks after weaning	150
Piglets from 5th week after weaning up to 8 weeks after weaning	100
Crustaceans	50
Other animals	25

TABLE 4. Selection of experimental groups to illustrate the effects of copper lysinate sulfate on zootechnical performance, blood chemistry and gross pathology parameters of chickens for fattening (■■■■■).

Parameters	Treatment groups
	Control	Cu‐Lys 1×	Cu‐Lys 11×
Copper (mg/kg)
Intended	■■■■■	■■■■■	■■■■■
Analysed (■■■■■)	■■■■■	■■■■■	■■■■■
Mortality, (1) % – (n)	1.67 (4)	1.25 (3)	1.67 (4)
Performance parameters
Final body weight (g)	2264	2239	2241
Feed intake (g/day)	93.3	92.6	91.6
Daily weight gain (g/day)	63.2	62.6	62.5
Feed to gain ratio	1.48	1.48	1.47
Blood parameters (2)
Haematocrit (%)	■■■■■	■■■■■	■■■■■
Glucose (mg/dL)	■■■■■	■■■■■	■■■■■
Magnesium (mg/dL)	■■■■■	■■■■■	■■■■■
Uric acid (mg/dL)	■■■■■	■■■■■	■■■■■
C‐reactive protein (ng/mL)	■■■■■	■■■■■	■■■■■

TABLE 5. Selection of experimental groups to illustrate the effects of copper supplementation from either source (■■■■■) on copper deposition in tissues and relevant blood parameters in chickens for fattening (■■■■■).

Parameters	Treatment groups
	Control	Cu‐Lys 1×	■■■■■ 1×
Copper in feed (mg/kg)
Intended	■■■■■	■■■■■	■■■■■
Analysed (starter/grower)	■■■■■	■■■■■	■■■■■
Copper deposition in tissues (mg/kg DM) (1)
Liver	■■■■■	■■■■■	■■■■■
Tibia (2)	■■■■■	■■■■■	■■■■■
Breast muscle	■■■■■	■■■■■	■■■■■
Kidneys	■■■■■	■■■■■	■■■■■
Feathers (3)	■■■■■	■■■■■	■■■■■
Blood markers
Cu (mg/L)	■■■■■	■■■■■	■■■■■
Superoxide dismutase (SOD) (IU/mL)	■■■■■	■■■■■	■■■■■

Full text

INTRODUCTION

1

Background and Terms of Reference

1.1

Regulation (EC) No 1831/20031 establishes the rules governing the Community authorisation of additives for use in animal nutrition. In particular, Article 4(1) of that Regulation lays down that any person seeking authorisation for a feed additive or for a new use of feed additive shall submit an application in accordance with Article 7.

The European Commission received a request from Phytobiotics Futterzusatzstoffe GmbH2 for the authorisation of the additive consisting of copper lysinate sulfate, when used as a feed additive for all animal species (category: nutritional additives; functional group: compounds of trace elements).

According to Article 7(1) of Regulation (EC) No 1831/2003, the Commission forwarded the application to the European Food Safety Authority (EFSA) as an application under Article 4(1) (authorisation of a feed additive or new use of a feed additive). The dossier was received on 3 January 2024 and the general information and supporting documentation are available at https://open.efsa.europa.eu/questions/EFSA‐Q‐2024‐00001. The particulars and documents in support of the application were considered valid by EFSA as of 10 April 2024.

According to Article 8 of Regulation (EC) No 1831/2003, EFSA, after verifying the particulars and documents submitted by the applicant, shall undertake an assessment in order to determine whether the feed additive complies with the conditions laid down in Article 5. EFSA shall deliver an opinion on the safety for the target animals, consumer, user and the environment and on the efficacy of the feed additive consisting of copper lysinate sulfate, when used under the proposed conditions of use (see Section 3.1.3).

Additional information

1.2

The additive copper lysinate sulfate has not been previously authorised as a feed additive in the European Union.

DATA AND METHODOLOGIES

2

Data

2.1

The present assessment is based on data submitted by the applicant in the form of a technical dossier3 in support of the authorisation request for the use of copper lysinate sulfate as a feed additive.

The confidential version of the technical dossier was subject to a target consultation of the interested Member States from 12 April 2024 to 12 July 2024; the comments received were considered for the assessment.

In accordance with Article 38 of the Regulation (EC) No 178/20024 and taking into account the protection of confidential information and of personal data in accordance with Articles 39 to 39e of the same Regulation, and of the Decision of EFSA's Executive Director laying down practical arrangements concerning transparency and confidentiality,5 a non‐confidential version of the dossier has been published on Open.EFSA.

According to Article 32c(2) of Regulation (EC) No 178/2002 and to the Decision of EFSA's Executive Director laying down the practical arrangements on pre‐submission phase and public consultations, EFSA carried out a public consultation on the non‐confidential version of the technical dossier from 28 August to 18 September 2024 for which no comments were received.

The FEEDAP Panel used the data provided by the applicant together with data from other sources, such as previous risk assessments by EFSA or other expert bodies, peer‐reviewed scientific papers, other scientific reports and experts' knowledge, to deliver the present output.

EFSA has verified the European Union Reference Laboratory (EURL) report as it relates to the methods used for the control of the active substance in animal feed.6

Methodologies

2.2

The approach followed by the FEEDAP Panel to assess the safety and the efficacy of copper lysinate sulfate is in line with the principles laid down in Regulation (EC) No 429/20087 and the relevant guidance documents: Guidance on the assessment of the safety of feed additives for the consumer (EFSA FEEDAP Panel, 2017a), Guidance on the identity, characterisation and conditions of use of feed additives (EFSA FEEDAP Panel, 2017b), Guidance on the assessment of the safety of feed additives for the target species (EFSA FEEDAP Panel, 2017c), Guidance on the assessment of the safety of feed additives for the environment (EFSA FEEDAP Panel, 2019), Guidance on studies concerning the safety of use of the additive for users/workers (EFSA FEEDAP Panel, 2023) and Guidance on the assessment of the efficacy of feed additives (EFSA FEEDAP Panel, 2024).

ASSESSMENT

3

The additive copper lysinate sulfate (Cu‐Lys) is intended to be used as a nutritional additive (functional group: compounds of trace elements) as a source of copper in feed for all animal species.

Characterisation

3.1

Characterisation of the additive

3.1.1

The additive is copper lysinate sulfate (Cu‐Lys).8 Copper lysinate sulfate is described as a 1:1 complex (copper: L‐lysine) with a chemical formula C_6_H_14_CuN_2_O_6_S·2H_2_O and structural formula [Cu(Lys)(H_2_O)2]SO_4_.9 The International Union of Pure and Applied Chemistry (IUPAC) name is diaquamonolysinatocopper(II) sulfate; the molecular weight is 341.82 g/mol.

Infrared (IR) spectroscopic data supported the formation of a complex.10

The additive is specified to contain a minimum of 18% copper, 40% lysine and less than 10% moisture. Data on the batch‐to‐batch variation11 and impurities12 are presented in Table 1 and on the physical and physico‐chemical properties13 of the additive are shown in Table 2.

The data provided showed compliance with the proposed specifications for copper lysinate sulfate, except from one batch in which the copper values were slightly below the specification.

The FEEDAP Panel considers that the microbial contamination and the amounts of the detected impurities do not raise safety concerns, except nickel which is further addressed in the user safety section.

Manufacturing process

3.1.2

The additive is produced by mixing the raw ingredients ■■■■■■■■■■ ■■■■■■■■■■ ■■■■■■■■■■ ■■■■■■■■■■ ■■■■■■■■■■ ■■■■■

Conditions of use

3.1.3

The additive is intended for use in feed for all animal species up to the maximum authorised total copper content in complete feeds, as reported in Table 3:

Safety

3.2

Safety for the target species

3.2.1

The applicant provided a combined tolerance and efficacy study in chickens for fattening to support the safety for the target species.19

■■■■■ The intended and analysed dietary copper levels are provided in Table 4. ■■■■■.

■■■■■. Blood samples were obtained ■■■■■ on day 35 for haematology20 and biochemical21 analysis. Additionally, at 35 days, ■■■■■ ■■■■■ were killed for superoxide dismutase (SOD) analysis in blood and the copper content determination in breast, liver, bone (tibia) tissues, kidneys and feathers.

■■■■■

The main results of the study are presented in Table 4. No differences were observed in mortality or any of the performance parameters due to the supplementation with Cu‐Lys at any of the levels tested.

For the blood biochemical parameters, no statistically significant differences were found between the groups that received the additive and the control group, except for a decrease in the concentration of uric acid (■■■■■) and C‐reactive protein (■■■■■) in the 11× group. In both cases, the variations are within physiological ranges and do not present safety concerns.

The results of the tolerance study indicate that the additive is safe for chickens for fattening at the currently authorised maximum level of copper in feed.

Conclusions on safety for the target species

3.2.1.1

The FEEDAP Panel concludes that the additive is safe for chickens for fattening at the maximum authorised levels of copper in feed. This conclusion is extrapolated to all animal species and categories at the respective maximum authorised levels in the EU for total copper in feed.

Safety for the consumer

3.2.2

Copper lysinate sulfate likely dissociates under physiological conditions into its three main components: lysine, sulfate and copper. Therefore, the FEEDAP Panel considers that only potential exposure to copper is of interest concerning the consumer safety.

The toxicology of copper compounds has been reviewed by the FEEDAP Panel, the Panel on Nutrition, Novel Foods and Food Allergens (NDA) and the Scientific Committee of EFSA (SC) (EFSA FEEDAP Panel, 2016; EFSA NDA Panel, 2015; EFSA SC, 2023). Under normal circumstances, copper homoeostasis ensures that copper overload in humans does not occur. An excess of copper has been recorded and shown to cause problems only under certain specific conditions, notably genetic disorders such as Wilson disease (EFSA NDA Panel, 2015). The primary target of copper toxicity is the hepatocyte and copper excess impair liver function (European Commission, 2003).

Dietary upper levels (ULs) for copper have already been established by the Scientific Committee on Food (SCF) for different population classes (European Commission, 2003). The SCF derived a tolerable upper intake level (UL) of 5 mg Cu/day for adults and extrapolated UL for toddlers, children and adolescents (e.g. UL of 1 mg/day for toddlers). More recently, the EFSA SC re‐evaluated the existing health‐based guidance values for copper and exposure assessment from all sources and established an acceptable daily intake (ADI) for copper (EFSA SC, 2023). In establishing this ADI, EFSA SC placed emphasis on hepatic copper retention as an early marker of potential adverse effects. The relationships between (a) chronic copper exposure and its retention in the body, particularly the liver and (b) hepatic copper concentrations and evidence of toxicity were examined. The SC concluded that no hepatic retention of copper is expected to occur with intake of 5 mg/day and established an ADI of 0.07 mg/kg bw, equivalent to 5 mg Cu/day for adults. The FEEDAP Panel notes that this ADI is established for the general population and that ULs for all age groups are established by the NDA Panel in line with the NDA Panel Guidance on establishing and applying tolerable upper intake levels for vitamins and essential minerals (EFSA NDA Panel, 2022).

Data on copper deposition following the use of the additive under assessment were available from the study on tolerance/bioavailability in chickens for fattening (see Section 3.2.1). In this study animals were supplemented with ■■■■■ from either ■■■■■ or Cu‐Lys, and samples of kidney, liver, muscle, tibia and feathers were taken on ■■■■■.

The main results are reported in the efficacy section (see Table 5, Section 3.3). All the results of copper deposition in liver, kidney and muscle were below the limit of quantification (LOQ) (5 mg/kg).

The FEDAP Panel notes that the LOQ of the method of analysis22 used (5 mg/kg) is very high and did not allow to identify possible differences in tissue deposition either among the copper lysinate sulfate and the control group or among copper supplementation from either source (copper lysinate sulfate vs. ■■■■■) (Section 3.2.1). Therefore, a consumer exposure estimate that would allow to quantify the contribution of the additive to the total exposure of the consumer to copper cannot be calculated. In addition, the FEEDAP Panel notes that no data on deposition of copper in skin and fat were submitted.

Due to these limitations and in the absence of reliable deposition data, the FEEDAP Panel cannot perform an exposure assessment of consumers to copper derived from food animal origin and therefore, cannot conclude on the safety of the additive for the consumer.

Safety for the user

3.2.3

Based on the highest dusting potential measured (see Table 2), the FEEDAP Panel considers that the exposure of users through inhalation is likely.

The additive contains copper, for which an occupational exposure limit (OEL) of 0.01 mg/m^3^ is set for the respirable fraction (European Commission, 2014).

The FEEDAP Panel notes that the additive contains nickel (see Table 1). The European Directive 2022/43123 set an OEL of 0.01 and 0.05 mg/m^3^ for both respirable and inhalable fraction, respectively as nickel meets the criteria for classification as carcinogenic (category 1A). Therefore, to reduce the risk, the FEEDAP Panel considers that the exposure of the users should be minimised. Additionally, due to the presence of nickel the additive should be considered as a skin and respiratory sensitiser.

The skin irritation potential of the additive was tested in a study performed according to the Organisation for Economic Co‐operation and Development (OECD) Guidelines for the Testing of Chemicals (TG) 439,24 which showed that the additive is not a skin irritant (UN GHS No Category).

The eye irritation potential of the additive was tested in a study performed according to OECD TG 437.25 Based on the results obtained, a prediction could not be made (No standalone prediction can be made).

Conclusions on safety for the user

3.2.3.1

The FEEDAP Panel cannot conclude on the eye irritation potential. The additive is not a skin irritant but should be considered a skin and respiratory sensitiser. Inhalation and dermal exposure are considered a risk.

Safety for the environment

3.2.4

The additive under assessment contains copper, l‐lysine and sulfate. The environmental risk assessment is made assuming that the whole amount of the additive ingested by the animals is excreted.

Sulfates are naturally abundant in the environment and the use of the additive will not result in a substantial increase above its background concentration under the current conditions of use.26

The amino acid l‐lysine is a physiological and natural component in animals and plants. When supplemented to feed, as component of the additive under assessment, it will be incorporated into animal proteins and any potential excess will be catabolised and excreted.

To assess the environmental risk of copper from the additive, the Panel compared the worst‐case predicted environmental concentrations (PECs)27 calculated at the maximum authorised level of copper with the natural background concentration considered as 90th percentile value from FOREGS database. If the predicted concentrations (PECs) fall below 10% of this value, no further risk assessment is needed. Determination of the natural background concentration for metals in water is described in the Guidance for implementing environmental quality standards (EQSs) for metals, by the Water Framework Directive implementation strategy.28

The 90th percentile concentration of copper in soil based on 840 topsoil samples collected throughout Europe for the FOREGS survey was 34 mg Cu/kg. The 90th percentile concentration of copper in freshwater obtained from occurrence data from 808 water samples collected throughout Europe for the FOREGS survey was 2.45 μg Cu/L.

As regards the use of the additive in terrestrial farm animals, piglets were considered as the worst‐case scenario. The worst‐case PEC_soi l_– after 1 year application29 at the maximum authorised level (150 mg Cu/kg), is 2.5 mg Cu/kg soil dw for piglets. Compared with the 10% of the natural background concentration of copper in soil, corresponding to 3.4 mg Cu/kg soil dry weight (FOREGS, 2005)30, the calculated PEC_soil_ is below this value. Therefore, no concerns are expected for the terrestrial compartment at the authorised conditions of use.

Considering the use of the additive in aquaculture, the highest PEC in surface water (land‐based aquaculture) for sea bass/sea bream is of 0.063 μg Cu/L, which is below 0.24 μg/L (10% of the natural background concentration in surface waters reported by FOREGS, see above). No safety concerns are expected from the use of the additive in land‐based aquaculture at the authorised conditions of use.

When the additive is used in marine aquaculture (sea cages), the PEC for marine sediment (PEC_sed_) is 55 mg Cu/kg sediment dry weight. The applicant provided information from the Oslo and Paris Conventions (OSPAR) commission (2014) indicating that copper has a background concentration in marine sediment of 20 mg/kg sediment dry weight, which is lower than the estimated concentration in marine sediments. The applicant, in addition, referred to the copper predicted no effect concentration in sediment (PNEC_sed_) of 338 mg Cu/kg dw (Monteiro et al., 2010), derived using the equilibrium partitioning approach. The FEEDAP Panel notes that, although the calculated PEC_sed_ exceeds the reported median copper level in marine sediment (OSPAR Commission, 2014), the ratio PEC/PNEC is lower than 1, indicating no safety concerns for marine sediment.

Considering the above, the FEEDAP Panel concludes that the use of the additive under the proposed conditions of use is safe for the environment.

Efficacy

3.3

The applicant provided a combined tolerance/efficacy study in chickens for fattening (see Section 3.2.1)31 in which copper deposition in liver, muscle, kidney, tibia and feathers as well as the copper content in blood were measured (Table 5). Additionally, the applicant provided the serum levels of SOD and supportive evidence of its reliability as a copper marker in blood.

All determinations of copper in liver, kidney and muscle were reported as below the LOQ of the analytical method employed (5 mg/kg DM). The FEEDAP Panel notes that this LOQ is markedly higher than the physiological concentrations normally found in these tissues (≤ 3 mg/kg DM for liver in chickens for fattening). Consequently, the method lacked the sensitivity needed to detect potential differences between treatments, and no information on hepatic copper deposition – the primary biomarker of copper status – could be generated.

Serum copper concentrations and SOD activity in blood did not differ between the control group and the groups receiving ■■■■■ from either copper lysinate sulfate or ■■■■■. The analysed copper content of the control diet (■■■■■) already met the nutritional requirements for chickens for fattening; therefore, any additional copper supplied by the test products was unlikely to translate into measurable changes in systemic biomarkers.

The FEEDAP Panel considers the main limitations of the study, and namely (i) the insufficient analytical sensitivity for tissue copper measurement and (ii) the adequate copper supply in the control diet likely preventing the study from demonstrating any bioavailability or biological response attributable to copper lysinate sulfate. Therefore, the FEEDAP Panel is not in the position to conclude on the efficacy of the additive.

Post‐market monitoring

3.4

The FEEDAP Panel considers that there is no need for specific requirements for a post‐market monitoring plan other than those established in the Feed Hygiene Regulation32 and Good Manufacturing Practice.

CONCLUSIONS

4

The FEEDAP Panel concludes that the additive copper lysinate sulfate is safe for all animal species and categories at the respective maximum authorised total copper levels in feed.

In the absence of adequate deposition data, the FEEDAP Panel cannot conclude on the safety of the additive for the consumer.

The additive is not a skin irritant. The FEEDAP Panel cannot conclude on the eye irritation potential due to the lack of data. The additive should be considered a skin and respiratory sensitiser. Inhalation and dermal exposure are considered a risk.

The FEEDAP Panel concludes that the use of the additive under the proposed conditions of use is safe for the environment.

The Panel is not in the position to conclude on the efficacy of the additive at the maximum authorised inclusion level.ABBREVIATIONSADIacceptable daily intakeANSEFSA Scientific Panel on Additives and Nutrient Sources added to FoodBWbody weightCASChemical Abstracts ServiceCFUcolony forming unitDMdry matterECHAEuropean Chemicals AgencyEINECSEuropean Inventory of Existing Chemical SubstancesEMAEuropean Medicines AgencyEQSenvironmental quality standardsEURLEuropean Union Reference LaboratoryFEEDAPEFSA Scientific Panel on Additives and Products or Substances used in Animal FeedGLMgeneral linear modelIRinfraredIUPACInternational Union of Pure and Applied ChemistryLOQlimit of quantificationNDAPanel on Nutrition, Novel Foods and Food AllergensOECDOrganisation for Economic Co‐operation and DevelopmentOELoccupational exposure limitOSPAROslo and Paris ConventionsPECspredicted environmental concentrationsPECsedPEC for marine sedimentPNECsedpredicted no effect concentration in sedimentRHrelative humiditySCFScientific Committee on FoodSODsuperoxide dismutaseULsupper levelsWHOWorld Health Organization

REQUESTOR

European Commission

QUESTION NUMBER

EFSA‐Q‐2024‐00001

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PANEL MEMBERS

Roberto Edoardo Villa, Giovanna Azimonti, Eleftherios Bonos, Henrik Christensen, Mojca Durjava, Birgit Dusemund, Ronette Gehring, Boet Glandorf, Maryline Kouba, Marta López‐Alonso, Francesca Marcon, Carlo Nebbia, Alena Pechová, Miguel Prieto‐Maradona, Ilen Röhe and Katerina Theodoridou.

LEGAL NOTICE

The scientific output published implements EFSA's decision on the confidentiality requests submitted on specific items. As certain items have been awarded confidential status by EFSA, they are consequently withheld from public disclosure by redaction.