Registration Dossier

Administrative data

Endpoint:
extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)
Type of information:
other: Expert statement
Adequacy of study:
key study
Study period:
2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Expert statement based on toxicity data available.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Principles of method if other than guideline:
Expert statement based on toxicity data available.
GLP compliance:
no
Justification for study design:
Expert statement based on toxicity data available.

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrasodium hexacyanoferrate
EC Number:
237-081-9
EC Name:
Tetrasodium hexacyanoferrate
Cas Number:
13601-19-9
Molecular formula:
C6FeN6.4Na
IUPAC Name:
tetrasodium hexacyanoferrate
Details on test material:
- Name of test material (as cited in study report): Sodium ferrocyanide
- Molecular formula: Na4Fe(CN)6·10H2O
- Physical state: solid
- Analytical purity: 99.12%

Results and discussion

Results: P0 (first parental generation)

Effect levels (P0)

Remarks on result:
other: based on calculations no adverse effects are expected as exposure is below ADI.

Results: F1 generation

Effect levels (F1)

Remarks on result:
other: based on calculations no adverse effects are expected as exposure is below ADI.

Overall reproductive toxicity

Reproductive effects observed:
no

Any other information on results incl. tables

Sodium ferrocyanide is a yellow crystalline solid that is soluble in water. Despite the presence of the cyanide ligands, Sodium ferrocyanide has low toxicity because of the strong chemical bond between iron and the cyanide groups. The substance is used as a food additive, known as E 535, in the EU and added to food grade salt as an anticaking agent. For use as a food additive, the acceptable daily intake (ADI) has been evaluated by the Joint FAO/WHO Expert Committee on Food Additives in 1969, 1973 and 1974.(1) In these evaluations for food additives the level causing no toxicological effect was based on a short-term study in rat and determined to be 0.05% (= 500 ppm) in the diet, equivalent to 25 mg/kg bw/day. The acceptable (lifelong) daily intake for man is set at 0-0.025 mg/kg bw/day.(1)

Since the evaluation by the Joint FAO/WHO Expert Committee on Food Additives new toxicity data are available, as a long term (two year) toxicity study with rats (equivalent to OECD TG 453) and a developmental toxicity study in rats (OECD 414) have been conducted. In the long term toxicity study male and females rats (48/sex) were daily exposed to Sodium ferrocyanide, which was mixed in the food at 0, 50, 500 and 5000 ppm. In this study organ weight and histopathology were examined from reproductive and endocrine organs including adrenals, gonads, pituitary gland and thyroid gland. Sodium ferrocyanide in the diet did not adversely affect growth or general health of the rats in the three treatment groups. No dose-related variations were found in the haematology, urine analyses, organ weights, or in the (non-neoplastic and neoplastic) histopathology of organs or tissues in the exposed groups. This study also demonstrates absence of adverse effects on the reproductive organs, even after daily exposure during 2 years. From these data, the NOAEL was determined to be ≥ 630 and ≥ 450 mg/kg bw/day for females and males, respectively, based on the absence of effects seen at the highest concentration (5000 ppm in the food). In addition to this study, results from an OECD 414 oral developmental toxicity study are now available. Rats were dosed up to and including 1000 mg/kg/day of Sodium ferrocyanide via gavage. No treatment related effects were observed, resulting in an NOAEL of ≥ 1000 mg/kg/day for both maternal and developmental toxicity.

Although new long-term toxicity data have become available Sodium ferrocyanide has not been re-evaluated for acceptable daily intake by the Joint FAO/WHO Expert Committee on Food Additives more recently. The new available data on long-term exposure and developmental toxicity support that Sodium ferrocyanide can be considered safe for reproductive and developmental toxicity, as considered earlier by EFSA by deriving an ADI without further request for information.

The expression of toxicity arising from exposure to a substance is a consequence of a chain of events that results in the affected tissues of an organism receiving the ultimate toxicant in amounts that cause an adverse effect. For reproductive and developmental effects to arise oral, dermal or inhalation exposure should lead to systemic exposure. The presence of ionisable groups and the moderate high molecular weight of Sodium ferrocyanide are indicative for impaired absorption, as ionized substances do not easily pass the gastro-intestinal wall. It is therefore likely that sodium ferrocyanide will show limited systemic exposure (10%) after oral administration. It is generally accepted that dermal absorption is lower compared to oral absorption and therefore dermal absorption will also be limited, with a worse case assumption of 10%. In humans, particles with aerodynamic diameters below 100 µm have the potential to be inhaled. Based on the particle size of sodium ferrocyanide, particles <100µm which have the potential to be inhaled, are not present and therefore inhalation exposure is considered to be negligible. Overall, systemic exposure to Sodium ferrocyanide is expected to be low for oral and dermal exposure and not relevant for inhalation exposure.Dermal exposure of workers is considered negligible. Personal protective equipment is used during charging after which the product enters a closed batch process. Therefore, dermal exposure to Sodium ferrocyanide is not relevant, and there is no indication for potential risk of workers. For consumer use, The Nordic Working Group on Food Toxicology and Risk Assessment evaluated the safety of use of Sodium ferrocyanide as an anticaking agent in salt and salt substitutes up to and including 20 mg/kg salt. It was calculated that the ADI can only be reached by consuming 75 g salt (adult) per day.(2) This is not a reliable amount of lifetime daily intake with a normal diet (an adult’s reference intake is 6 g of salt a day), therefore exposure to Sodium ferrocyanide from this source of exposure is considered not posing a risk.

Sodium ferrocyanide is also used in anti-freeze and de-icing products for consumer use at circa 50 mg/kg product. To compare the level of exposure with the value of the ADI, an equivalent of 30 g of anti-freeze or de-icing product has to be taken up lifelong every day either by the oral or dermal route. As these products are not intended for human consumption, daily uptake of such high amounts via the oral route is not relevant.

To estimate consumer exposure by the dermal route, a default scenario is considered in which a consumer uses a de-icing product, such as road salt, for 1 hour per day distributing the product with their hands. A daily lifelong contact rate of 0.5 gram/minute is needed to reach a similar level of exposure as ADI, which is considered unrealistic. No reference exposure scenario for anti-freeze and de-icing products is available, however the Technical Notes for Guidance (TNsG) on Human Exposure to Biocidal Products describe a ‘Consumer product spraying and dusting’ model with an indicative exposure via hands/forearms of 2.73 mg/min.(3)Considering that the daily lifelong contact rate needed to reach a similar level of exposure as ADI (500 mg/min) is much higher than the estimated exposure based on the model (2.73 mg/min) and the fact that the dermal absorption is low (10%) it is highly unlikely that consumer use of products containing Sodium ferrocyanide will lead to exposures that exceed the ADI. The ADI indicates safe use for all toxicological endpoints, including reproductive and developmental toxicity, and therefore there is no indication for potential risk by exposure via the dermal route.

Based on all available toxicological data of Sodium ferrocyanide there is no indication for systemic effects. The occurrence of reproductive or developmental toxicity in the absence of any systemic toxicity up to and including 450 mg/kg bw/day is highly unlikely for an industrial chemical without specific working mechanism. The low systemic availability combined with the absence of systemic effects in available data clearly demonstrates that Sodium ferrocyanide has a low potential for toxicity.

Absence of developmental toxicity in rat has already been demonstrated in a developmental toxicity study (OECD 414). The relevance (need) of rabbit developmental toxicity data for human risk assessment, in the absence of other systemic toxicity data in rabbits and absence of systemic toxicity in rat, is questionable, as scientific data indicating that rabbit data on Sodium ferrocyanide are more relevant for human risk assessment than rat data are lacking.

Conclusion

Sodium ferrocyanide is a food additive known as E 535 in the EU and added to salt as an anticaking agent with an ADI for man set at 0-0.025 mg/kg bw/day.(1) Exposure to Sodium ferrocyanide is negligible for workers, as the substance is used in a closed batch process. Calculations show that, for the general population, lifelong intake of products containing Sodium ferrocyanide has to be unrealistically high to exceed ADI. Consumer use of Sodium ferrocyanide in anti-freeze and de-icing products is expected to result in exposure well below ADI. As the exposure assessment using ADI indicates safe use, it is also considered safe for reproductive and developmental toxicity.

Based on the low potential for toxicity as derived from the toxicity data available and limited systemic exposure to Sodium ferrocyanide, no hazard and no risk is considered present for reproductive toxicity as well as developmental toxicity. Data from a developmental toxicity study (OECD 414) in rat demonstrate the absence of developmental toxicity, and there are no scientific data indicating rabbit developmental toxicity data (in the absence of systemic toxicity data) being more relevant for human risk assessment than rat data.

The available toxicity data have no indication for reproductive toxicity. As Sodium ferrocyanide is a chemical without specific working mechanism it is unlikely that this substance will specifically demonstrate reproduction toxicity in the absence of any systemic toxicity. Based on these considerations, additional toxicity data on reproduction toxicity and developmental toxicity is considered not scientifically justified and the Extended one-generation reproductive toxicity test (OECD 443) and a Developmental toxicity study, second species (OECD 414) can be waived.

References

1)   Eighteenth Report of the Joint FAO/WHO Expert Committee on Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 557. FAO Nutrition Meetings Report Series, 1974, No. 54.

2)   Food additives in Europe 2000 Status of safety assessments of food additives presently permitted in the EU. TemaNord 2002:560.

3)   Technical Notes for Guidance (TNsG). Human Exposure to Biocidal Products. Guidance on Exposure Estimation. https://echa.europa.eu/documents/10162/16960215/bpd_guid_tnsg-human-exposure-2007_en.pdf (page 63)

Applicant's summary and conclusion

Conclusions:
Based on the available data, sodium ferrocyanide is not classified for reproduction toxicity according to CLP Regulation (No) EC 1272/2008.