Fatty acids, tallow, zinc salts

Endpoint summary

Additional information

Justification for Read-across

There are no data available for the aquatic toxicity of Fatty acids, tallow, zinc salts (CAS 68440-34-0). In order to fulfil the standard information requirements set out in Annexes VII - IX, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances and from surrogate substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human and environmental toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity and common physiological active moieties.

Fatty acids, tallow, zinc salts consist of approximately 10% zinc and 90% natural fatty acids, mainly of saturated C16 and C18 fatty acids and monounsaturated C18 fatty acid.

In the case of Fatty acids, tallow, zinc salts, read-across to Fatty acids, zinc salts and to inorganic zinc salts and zinc metal (as listed below) was used. Justification for both approaches is given below.

Fatty acids, zinc salts

The target substances Fatty acids, tallow, zinc salts and the source substances Fatty acids, C16-18, zinc salts (CAS No. 91051-01-3), zinc distearate (CAS No. 557-05-1), zinc bis[12-hydroxystearate] (CAS No. 35674-68-1) and zinc dicaprylate (CAS No. 557-09-5) are substances with a zinc moiety and a fatty acid moiety. The zinc content is considered to be similar. The fatty acid moiety is considered not being hazardous to humans and the environment. Fatty acids are natural constituents of the human body and the environment and essential components of a balanced nutrition for humans and animals. Fatty acids are generally judged as not representing a risk to human health (except the irritating/corrosive properties of short-chain fatty acids and the environment. Variability in the poorly soluble fatty acid moiety is not expected to have a relevant influence on the physiological activity of fatty acid zinc salts and therefore, read-across to another fatty acid zinc salts is justified without restrictions.

Inorganic zinc salts

A basic assumption for read-across made in this hazard assessment and throughout this CSR is that the biological activities of Fatty acids, tallow, zinc salts are expected to be mainly determined by ionic zinc, in case of dissociation. Since water solubility is the main determinant of bioavailability, read-across to source substances with higher water solubility and thus higher bioavailability of the zinc cation can be considered as worst-case for the target substance fatty acids, tallow, zinc salts.

This read-across approach is in accordance with the read-across approach applied in the course of the EU Risk assessments within the framework of EU Existing Chemicals Regulation (EEC) No 793/93 on substances zinc metal (CAS No. 7440-66-6), zinc oxide (CAS No. 1314-13-2), zinc chloride (CAS No. 7646-85-7), zinc sulphate (CAS No. 7733-02-0), trizinc bis(orthophosphate) (CAS No. 7779-90-0) and the structural analogue to Fatty acids, tallow, zinc salts being zinc distearate (CAS No. 557-05-1 / 91051-01-3).

For a comprehensive overview of the environmental fate properties and environmental and toxicological information of “Zinc” see the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 in the technical dossier (see IUCLID Section 13).

 

Overview of source and target chemicals including CAS No./EC No.

Chemical Name	CAS No. / EC No.
Target substance
Fatty acids, tallow, zinc salts	68440-34-6 / 270-451-8
Source substances
Fatty acids, C14-18 and C16-18 unsatd., zinc salts	67701-12-6 / 266-936-9
Fatty acids, C16-18 and C18 unsatd., zinc salts	67701-13-7 / 266-937-4
Fatty acids, C16-18, zinc salts	91051-01-3 / 293-049-4
Zinc distearate	557-05-1 / 209-151-9
Zinc bis[12-hydroxystearate]	35674-68-1 / 252-669-5
Zinc dicaprylate	557-09-5 / 209-156-6
Zinc diacetate	557-34-6 / 209-170-2
Zinc dichloride*	7646-85-7 / 231-592-0
Zinc sulfate*	7733-02-0 / 231-793-3
Zinc nitrate*	7779-88-6 / 231-943-8
Zinc oxide*	1314-13-2 / 215-22-5
Zinc*#	7440-66-6 / 231-175-3

*) Surrogate substances (inorganic zinc salts)

#) The acceptance of zinc as surrogate refers to the cases where the specified CAS No. is given as test substance identity in the technical dossier with no further data on specification. In most cases this is presumably an ionic form, Zn²⁺.

A detailed read-across justification is provided in the technical dossier (see IUCLID Section 13).

Aquatic toxicity

Short-term aquatic data for the three trophic levels, fish, invertebrate and algae are available for the read-across substance Fatty acids, C16-18, zinc salts (CAS 91051-01-3). As described above and in the analogue justification in section 13, Fatty acids, C16-18, zinc salts (CAS 91051-01-3) and Fatty acids, tallow, zinc salts have very similar structures and properties, and the data can therefore be directly used for the aquatic hazard assessment of Fatty acids, tallow, zinc salts.

Long-term aquatic data on Fatty acids, C16-18, zinc salts (CAS 91051-01-3) are only available for algae. Since the biological activities of Fatty acids, tallow, zinc salts are expected to be mainly determined by ionic zinc (in case of dissociation) data available for inorganic zinc compounds can be used as supporting information for long term toxicity on fish and invertebrates.

Based on the zinc toxicity data, the most sensitive trophic level is represented by algae. Therefore, the hazard assessment of Fatty acids, tallow, zinc salts is likely to be determined by the chronic value of the algae study. Further long-term testing on fish or invertebrates with fatty acids, zinc salts would most probably not lead to lower effect values, and would thus not influence the hazard assessment. Based on this information, long-term studies on fish or aquatic invertebrates are not considered necessary for the hazard assessment of Fatty acids, tallow, zinc salts.

The relevant data for Fatty acids, C16-18, zinc salts and for inorganic zinc substances is discussed below.

Fatty acids, C16 -18, zinc salts:

Aquatic toxicity

Acute toxicity to invertebrates: The acute toxicity of Fatty acids, C16-18 zinc salts to Daphnia magna was determined according to OECD 202 in M7 medium at pH 6 and 8 (Bouwman et al., 2003). The EC50 (48 h) was not reached up to a loading rate of 100 mg Fatty acids, C16-18 zinc salts /L. At this loading, the zinc concentration at the beginning of the test was 1170 µg Zn/L at pH 6 and 800 µg Zn/L at pH 8. The test report concludes: “No daphnids became immobilised during the test period... Although all daphnids exposed to the undiluted water fraction had test substance on their bodies at the end of the test, this did not hinder them”. It is concluded, that the toxicity of the substance fatty acids, C16 -18, zinc salts to daphnia is (far) above the water solubility.

Acute toxicity to fish: Information on fish toxicity of Fatty acids, C16-18 zinc salts is available from a study performed according to EU Method C.1 (Acute Toxicity for Fish) in the former version of 1992 (Henkel KGaA, 1995), from a study performed according to OECD Guideline 203 (Fish, Acute Toxicity Test) but reported only in a short study report (TÜV Bayern, 1992) and from an old publication (Dowden and Bennett, 1965). In the most reliable study (Henkel KGaA, 1995), fish (Danio rerio) were exposed for 96 hours to nominal concentrations of 0 (control), 1000, 3000 and 10000 mg/L under semi-static conditions. The nominal concentrations far exceed the water solubility of Fatty acids, C16-18, zinc salts by 3 to 4 orders of magnitude. Measures to disperse the test substance in the test water were used. At all tested concentrations, including the highest nominal test concentration, neither behavioural abnormalities nor mortality occurred. In addition, no effects were observed at nominal Fatty acids, C16-18, zinc salts concentrations up to the water solubility limit in the two further studies. In accordance with the evaluation given in the EU Risk assessment on zinc distearate (Final report R074_0805_env, May 2008), it is concluded, that the toxicity of the substance Fatty acids, C16 -18, zinc salts to fish is (far) above the water solubility limit of around 1 mg/L.

Algae: The toxic effects of Water Accommodated Fractions (WAF) of Fatty acids, C16-18, zinc salts on the growth rate of algae (Pseudokirchneriella subcapitata) were studied in three state-of-the-art tests according to OECD Guideline 201 (Wenzel, 2010a,b; Wenzel, 2013). While in the first test, the WAF of a loading of 100 mg/L was diluted in series to allow the calculation of toxicity parameters (EC10, EC50), the WAFs of several loadings (1, 10, and 100 mg/L) were tested in the second test according to OECD Series No. 23 to enable the classification based on WAFs. The first study has to be disregarded with respect to the fact, that the preparation of test concentrations was done from one WAF in a series (Wenzel 2010a). In the second test the WAF were each prepared separately, but no loading-dependent inhibition was obtained (Wenzel 2010b). The inhibition was clearly higher at 1 mg/L loading than at 10 mg/L, so also this study has to be disregarded. Therefore, a further full test with test concentrations 0.01, 0.1, 1.0, 10.0, and 100 mg/L, each prepared separately as WAF, was conducted (Wenzel, 2013). This study was also performed according to OECD Guideline 201 and GLP. Since a loading-dependent inhibition was observed and also the further validity criteria according to OECD 201 were met, this study can be assessed as valide and the effect values for growth rate could be taken into account. The ErL50 (72 h), ErL10 (72 h) and the NOEL (72) were stated as > 100 mg/L, 3.31 mg/L and 0.1 mg/L, respectively.

For further hazard assessment, the EC10 was used as chronic value, as recommended by the Guidance on information requirements and chemical safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment Table R.10-1 (ECHA, 2008). As stated in the guidance document, there has been a recommendation within OECD in 1996 to phase out the use of the NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. Also the OECD Guideline 201 states: “Recent scientific developments have led to a recommendation of abandoning the concept of NOEC and replacing it with regression based point estimates ECx. An appropriate value for x has not been established for this algal test. A range of 10 to 20 % appears to be appropriate (depending on the response variable chosen), and preferably both the EC10 and EC20 should be reported.”(OECD, 2011).

ZINC:

1. Aquatic toxicity: freshwater, short-term

Establishing the dataset

In accordance to the approach followed in the EU Risk Assessment Report (RAR), only acute data from standardised test protocols were considered in the analysis for setting the reference value for classification. This is possible because numerous data are available, and it ensures that the tests were performed under rather well defined and standard conditions.

Still, the quality and some aspects of relevancy should be checked in a critical way when using the extensive datasets from the open literature, available for zinc. It is e.g. important to know the conditions under which the organisms were tested and cultured, because these conditions may result in acclimatisation and deviating toxicity response. The information on these test conditions is often scarce in non-standardised test reports.

The short-term aquatic ecotoxicity data base for zinc was reviewed according to the following principles:

-         The data accepted for setting the acute aquatic reference value in the RA (ECB 2008, Annex 1.3.2a, table 1) were as such also accepted and used for the present analysis. Prescriptions from standard protocols were strictly followed, e.g. data from an acute Daphnia test exceeding 48 hrs were not used.

-         Data that were rejected for use in the RAR (ECB 2008, Annex 1.3.2a, table 2) were also not used for the present analysis. In this respect, data from studies that were accepted for use in the chronic database, but rejected for use in the acute toxicity database were reconsidered; this resulted in the acceptance of a few additional data.

-         In accordance to the approach followed in the RA, acute data obtained in natural waters that contained e.g. significant amount of DOC, were not used. Exception to this rule were data obtained on the N.-American Great Lakes waters, which were used, in accordance to the RAR.

-         Fish data mentioned in the RAR under “EHC 1996” were not used, since they were from a review, not from original study reports. These data are not influencing the outcome of the analysis, since they are all at the higher concentration level.

-         More recent (obtained after 1996 to the present) short-term acute toxicity data on standard organisms were included in the database.

After checking and updating the data base, the data are grouped per species as follows:

-pH: low (6 -<7) - neutral/high (7 -8.5)

-hardness: low/medium (< 100 mg CaCO3/L) and medium/high (>100 mg CaCO3/L).

If 4 or more data points were available on a same species, the geometric mean was calculated and used for the analysis.

Acute data – results

The short-term acute aquatic toxicity database covers 10 species (1 algae, 4 invertebrates and 5 fish species). The full set of EC50 values are presented together with the pH and hardness of the test media in the CSR. A significant number of data are available at both low and neutral/high pH.

Discussion: reference values for short term aquatic ecotoxicity

At low pH, 2 values are available for 2 daphnia species. The values are similar. They were obtained at lower hardness, where the highest sensitivity is expected, which is confirmed by the value > 530 µg/L, obtained on Ceriodaphnia dubia at high hardness. Algae are as a rule not tested under standardised conditions at low pH, but from chronic algae data (72 hrs NOECs), it is known that the sensitivity of algae is much lower at lower pH. Simulation with the biotic ligand model gives an aquatic ecotoxicity value for algae at pH 6 which is about 5 times higher than the one observed at neutral/high pH. Fish toxicity at low pH is also not critical in this respect, so the values for the daphnids are representative for the sensitivity of organisms to zinc at low pH. The lowest value observed for Ceriodaphnia dubia is used for the classification at low pH.  

At neutral/high pH, the value obtained on the algae Selenastrum capricornutum is the lowest of the dataset. This value is taken forward as reference value for classification at this pH. This value is obtained at low hardness conditions, where sensitivity is highest. The same algae species is also the most sensitive in the chronic aquatic toxicity database (see below) so this sensitivity pattern is consistent. Among the daphnids, Ceriodaphnia dubia is also here the most sensitive, and the lowest value comes close to the one for the alga. From the paired data, it follows that the Daphnids are more sensitive at lower hardness than at the higher hardnesses. The fish are also at this pH less sensitive to zinc, although the lowest value observed on O. mykiss also comes close to the reference value. All together, the lowest values among the species show also here a consistent pattern, supporting the lowest value identified.

In conclusion, the reference values for the Zn++ ion that are used for the aquatic toxicity hazard assessment of Zn++ are:

for low pH: 0.413 mg Zn/l (based on single lowest value for Ceriodaphnia dubia)

for the neutral/high pH: 0.136 mg Zn/l (based on single lowest value for Selenastrum capricornutum (=Pseudokirchneriella subcapitata)

2. Aquatic chronic toxicity: freshwater

Chronic data - establishing the dataset

In this analysis, like in the RAR, the results of the chronic aquatic toxicity studies are expressed as either the actual (measured) concentration or as the nominal (added) concentration (Cn). The actual concentrations include the background concentration (Cb) of zinc. Because of the “added risk approach”, the results based on actual concentrations have been corrected for background, if possible. This correction for background is based on the assumption that only the added concentration of zinc is relevant for toxicity. In case both actual and nominal concentrations were reported, the results are expressed in the RAR (and in this CSR) as nominal concentrations, provided the actual concentrations were within 20% of the nominal concentrations.

Many of the reported aquatic toxicity data (either actual or nominal) represent total-zinc concentrations, i.e. the dissolved plus particulate fraction. However, the results are regarded as being dissolved-zinc concentrations, because under the conditions that were used in the laboratory tests, it is assumed that the greater part of zinc present in the test waters was in the dissolved fraction. This is especially true for the long-term studies, e.g. by using flow-through systems, in which particulate matter (suspended inorganic material and/or organic matter) was removed from the artificial test waters or natural waters. The fact that in ecotoxicity testing the nominal added concentration of zinc is very close to the actually measured zinc concentration, is also demonstrated by the many data reported in the papers of the chronic aquatic ecotoxicity database. Also in static and flow-through acute toxicity studies with several saltwater species, dissolved zinc was greater than 93% of the total zinc. Therefore, the PNECaddvalues derived from the aquatic toxicity studies are considered to be relevant for dissolved zinc.

The chronic aquatic toxicity dataset for zinc was checked according to the general criteria for data quality:

-study design preferably conform to OECD guidelines or equivalent

-Toxicological endpoints, which may affect the species at the population level, are taken into account. In general, these endpoints are survival, growth and reproduction.

- whether or not NOEC values are considered chronic is not determined exclusively by exposure time, but also by the generation time of the test species, e.g. for unicellular algae and other microorganisms (bacteria; protozoa), an exposure time of four days or considerably less already covers one or more generations, especially in water, thus for these kinds of species, chronic NOEC values may be derived from relatively short experiments. For PNEC derivation a full life-cycle test, in which all relevant toxicological endpoints are studied, is normally preferred to a test covering not a full life cycle and/or not all relevant endpoints. However, NOEC values derived from tests with a relatively short exposure time may be used together with NOEC values derived from tests with a longer exposure time if the data indicate that a sensitive life stage was tested in the former tests.  

-If for one species several chronic NOEC values (from different tests) based on the same toxicological endpoint are available, these values are averaged by calculating the geometric mean, resulting in the “species mean” NOEC.

-If for one species several chronic NOEC values based on different toxicological endpoints are available, the lowest value is selected. The lowest value is determined on the basis of the geometric mean if more than one value for the same endpoint is available.

-In some cases, NOEC values for different life stages of a specific organism are available. If from these data it appeared that a distinct life stage was more sensitive, the result for the most sensitive life stage is selected. The life stage of the organisms is indicated in the tables as the life stage at start of the test (e.g. fish: yearlings) or as the life stage(s) during the test (e.g. eggs/larvae, which is a test including the egg and larval stage).

-Only the results of tests in which the organisms were exposed to zinc alone are used, thus excluding tests with metal mixtures.

-Like in the RAR, unbounded NOEC values (i.e. no effect was found at the highest concentration tested) are not used.

-If the NOEC was < 100 µg/L, the separation factor between the NOEC and LOEC should not exceed a factor of 3.2.

-If the EC10 was used as NOEC equivalent, the EC10 should not be more than 3.2-times lower than the lowest concentration used in the test.

-Like in the RAR, only the results of tests with soluble zinc salts are used, thus excluding tests with “insoluble” zinc salts (ZnO, ZnCO3), unless dissolved zinc is measured.  

Referring to the EU RAR on zinc (ECB 2008), all the data that were accepted for deriving the freshwater PNEC in the RA (ECB 2008, Annex 3.3.2.A. part I) were as such also accepted for the present analysis. On the other hand, the data that were considered not useful for the purpose of PNEC derivation in the RAR (ECB 2008, Annex 3.3.2.A. part II), were also not used for the present analysis.

 The relevance of the long-term aquatic ecotoxicity data base for PNEC derivation was further checked in accordance to the same principles as those applied in the RAR (ECB 2008). Relevance was checked

1) related to the zinc background: in accordance to the RAR (ECB 2008), a level of 1µg/L Zn was set as a cut-off for this.

2) related to test medium conditions: Zinc ecotoxicity to aquatic organisms is a function of the physicochemical characteristics of the water. Parameters such as hardness, pH, dissolved organic carbon (DOC) are well-known drivers for zinc ecotoxicity. For this reason, it was considered important in the EU RA to select ecotoxicity data that were obtained under test conditions similar to the conditions observed in EU waters. Based on information related to the parameters mentioned above in EU waters, the following boundaries for EU relevance for pH, hardness have been used in the RA (ECB 2008) and also in the present analysis for data selection, also considering OECD test guidelines:

pH:                             minimum value: 6

                                   maximum value: 9

Hardness:                   minimum value: 24 mg/l (as CaCO3)

                                   maximum value: 250 mg/l (as CaCO3)          

As indicated above, background zinc concentration was also considered in the RA to be a factor influencing the toxicity response of organisms to zinc; to avoid influence of acclimatisation towards very low or very high zinc concentrations (not occurring in the EU waters), a minimum value for soluble zinc was also set in the RA for data selection: “around 1 µg/L” (ECB 2008).

Data obtained under conditions failing these relevance criteria were not used for PNEC derivation in the present analysis. For a detailed description of the relevance criteria and their application in the RA, see the RAR (ECB 2008).

It is realised that the selected ranges of the three criteria will not cover all European aquatic systems, e.g. specific aquatic systems in the Scandinavian countries. In particularly, hardness is much lower in the Scandinavian countries, although also other abiotic parameters differ from the ‘average’ situation in European freshwaters. Therefore, a “soft water PNECadd, aquatic” has been derived in the RA process, in addition to the generic PNECadd, aquatic. The present analysis however relates to the development of a generic PNEC for EU waters.

DOC: Tests have been considered relevant for the present analysis if DOC concentrations in the test media are between 0 mg/l and 13 mg/l. In most test solutions, DOC is not present.

The extensive dataset on chronic aquatic toxicity in the RA (ECB 2008) was also updated with new information. This information was screened for the same criteria as those described above.

For details on data selection see the chemical safety report for zinc.

Results

The 23 distinct chronic species ecotoxicity values that were used for the SSD in the present analysis are summarised in the CSR. The “species mean” NOEC values used for PNEC derivation (freshwater PNECadd, aquatic), range from 19 to 530 µg/L.

The reference values for chronic aquatic toxicity were determined:

-at pH 8: from the extensive chronic ecotoxicity data available for algae, invertebrates and fish (section 7.1.1., 2.). The standard species NOEC values for each taxonomic group for which a bioavailability model is available were taken at pH 8, and the lowest of the 3 was selected as a reference value at pH 8.

-at pH 6: the corresponding aquatic toxicity at pH 6 was calculated from the same database for the standard species for which bioavailability models were available, and the lowest of the 3 was selected as a reference value at pH 6.

The results are summarised below:

-for algae, the NOEC of the BLM-species Pseudokirchneriella subcapitata is the lowest of the SSD at pH 8 (19 µg/l). This value corresponds to a water of pH 8,0,  hardness 24 mg CaCO3 and DOC 2.0 mg/l. With the BLM, a corresponding species NOEC of 142 µg/l is calculated for this species at pH 6 (other water conditions same).

-for invertebrates, the BLM-species Daphnia magna gives a species mean at pH 8 of 98 µg/l, corresponding to a water of pH 8, hardness 24 mg CaCO3/l and DOC 1,2 mg/l.  The Dapnia magna-BLM predicts at pH 6 (other water conditions same) a species NOEC of 82 µg/l.

-for O. Mykiss, the species mean at pH 8 is 146 µg/l (hardness 45 mg/l, DOC 2 mg/l). Using the corresponding species BLM gives a species NOEC of 146 µg/l at pH 6 (other conditions same).

From these data, the following reference values for chronic zinc aquatic toxicity are derived:

-at pH 8.0: 19 µg Zn/l (Pseudokirchneriella subcapitata)

-at pH 6.0: 82µg Zn/l (Daphnia magna)

3. Aquatic chronic toxicity: marine waters

For zinc, a specific effects assessment was made and a specific PNEC was derived for the marine environment, since there is a vast dataset available on marine ecotoxicity. This specific approach is also more reflective of the toxicity of zinc in the marine environment given the different speciation and bioavailability of zinc in salt – and freshwater, and differences in physiology of saltwater organisms. Given the vast amount of available toxicity data, statistical extrapolation was used to derive the marine PNEC. This marine effects assessment is following an added risk approach, as applied for the freshwater.

Sources of data

The ecotoxicological data were derived from original papers, published in peer-reviewed international journals. Literature and environmental databases, including AQUIRE (US EPA), MARITOX, ECETOC, and BIOSIS, as well as review articles covering zinc in marine waters were searched and reviewed for sources of relevant and reliable chronic toxicity data on zinc. Only original literature was used.

Data reliability and relevance

Selection of ecotoxicity data for quality was done according to a systematic approach as presented by Klimisch et al. 1997. Standardized tests, as prescribed by organizations such as ASTM, OECD and US EPA, are used as a reference when test methodology, performance and data treatment/reporting are considered. A detailed description of data reliability and relevancy is provided in the CSR for zinc.

Overall conclusion:

Based on the studies conducted with the structural analogue Fatty acids, C16 -18, zinc salts, the substance Fatty acids, tallow, zinc salts is not expected to have short-term effects on fish or aquatic invertebrates. The estimated ErL50 and ErL10 value for the 72-h inhibition of growth rate of algae is > 100 mg/L and 3.31 mg/L, respectively. These conclusions are consistent with conclusions from the EU RAR for the structural analogue Zinc distearate (CAS-No.: 557-05-1 & 91051-01-3; ECB, 2008). For microorganisms, the lowest effect value EC50 5.2 mg/L was obtained with zinc sulphate. This value was used for the hazard assessment as worst case.

Furthermore, the data available for inorganic zinc substances shows that algae represents the most sensitive trophic level for zinc, which is considered applicable for Fatty acids, tallow, zinc salts as well.