Fatty acids, C16-18 (even numbered), aluminum salts

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from reference substances with similar structure and intrinsic properties of dissociation products of the target substance. Read-across is justified based on dissociation products (refer to endpoint discussion for further details). The selected studies are thus sufficient to fulfil the standard information requirements set out in Annex VII, 8.5, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Toxicity to reproduction

No studies are available on toxicity to reproduction of Fatty acids, C16-18 (even numbered), aluminum salt. However, there are reliable data on analogue substances which are considered suitable for read-across.According to the general rules defined in Regulation (EC) No. 1907/2006, Annex XI, Item 1.5 for the grouping of substances and read-across approach, similarities between substances may be based on “common functional groups” and “common precursors and/or the likelihood of common breakdown products via physical and biological processes, which result in structurally similar chemicals”. Bonds between metal salts and carboxylic acids are known to readily dissociate into the corresponding metal and carboxylic acid in the ambient environment (at neutral pH) and in the digestive tract (at low pH) where complete dissociation occurs, as determined for aluminium di- and tristearate in the US HPV Chemical Challenge Program (2007). Thus, nearly complete dissociation of aluminum fatty acid salts into aluminium, stearic (C18) and/or palmitic (C16) acid is expected to occur in the digestive tract after oral ingestion thereby indicating that toxicity of Fatty acids, C16-18 (even numbered), aluminum salt can be evaluated based on reliable data for the dissociation products and structural analogues of those. The first dissociation product, C16 and 18 fatty acids are stepwise degraded within the mitochondrium matrix by β (–) Oxidation in which C2 units are released (CIR, 1987). Therefore, read-across to saturated fatty acids of different chain length is feasible because of the likelihood of common breakdown products. The second dissociation product,aluminium exists in 4 different forms in the living organisms, including free ions, low-molecular-weight complexes, physically bound macromolecular complexes, and covalently bound macromolecular complexes (Ganrot 1986). As the pathways leading to toxic outcomes are mainly dominated by the chemistry and biochemistry of the aluminium ion (Al³⁺) (Krewski et al., 2007; ATSDR, 2008), different aluminium compounds may serve as surrogates for read-across to the free metal component ofFatty acids, C16-18 (even numbered), aluminum salt.

As noted in Regulation (EC) No. 1907/2006, Article 13 (1) "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.” Information shall therefore be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related or surrogate substances (grouping or read-across) “to avoid the need to test every substance for every endpoint”. For details on the read-across approach please refer to the analogue justification in section 13 of the technical dossier.

As no data are available on toxicity to reproduction ofFatty acids, C16-18 (even numbered), aluminum salts, read-across to reliable data on the analogue and surrogate substances aluminium sulfate (CAS 10043-01-3) and docosanoic acid (CAS 124-07-2) was performed.

For aluminium sulfate, a two generation reproduction toxicity study is available according to the OECD Guideline 416 (Hirata-Koizumi et al., 2011). 24 Crl:CD(SD) rats per gender (F0 and F1 generation) were exposed to 120, 600 and 3000 ppm aluminium sulfate via drinking water beginning at 5 weeks of age for 10 weeks until mating, during mating, throughout gestation and lactation. Litters were normalized on PND 4. In the F1 generation, 24 male and 24 female weanlings were identified as parents on PNDs 21 to 25, ensuring an equal distribution of body weights across groups. The major findings included decreased water consumption for both sexes in all test groups, variable reductions in food consumption, reduced body weight in preweaning animals at the highest concentration, delayed sexual maturation of F1 female offspring in the high-dose group, and decreased absolute liver, epididymides, thymus and spleen weight in the offspring of the high-dose group. Based on the observed effects, a LOAEL of 31.2 mg aluminium/kg bw/day (3000 ppm aluminium sulfate) was derived for systemic toxicity in the parental generation which corresponds to 367.1 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day considering a content of up to 8.5% aluminium. As no effects on fertility were observed in either the parental or F1 generation, a NOAEL ≥ 31.2 mg aluminium/kg bw/day (3000 ppm aluminium sulfate) was derived for fertility corresponding 367.1 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day (based on a worst case assumption of up to 8.5% aluminium). Due to the effects observed in the F1 and F2 generation, a NOAEL of 9.78 aluminium/kg bw/day was set for developmental toxicity corresponding to 115.1 mgFatty acids, C16-18 (even numbered), aluminum salt/kg bw/day.

However, because “paired-comparison data are not available to assess the effects of decreased water intake in the absence of aluminium sulfate exposure” there is a possibility that observed developmental effects are the results of reduced water consumption and thus, the suggested NOAEL for developmental toxicity was defined rather conservative. The statistically significant delay in F1 females’ vaginal opening (29.5 ± 2.1 in controls and 31.4 ± 1.7 days in the highest dose group) was not accompanied by adverse changes in oestrous cyclicity, anogenital distance or further reproductive performance. Further, interpretation of the results is difficult due to the effect on water consumption which might be due to reduced pH (3.57 to 4.2) of the drinking water supplemented with high doses of aluminium which appears to reduce the palatability of the drinking water. At the tested concentration levels, the F0 and F1 females also decreased their food consumption relative to the controls during week 3 of lactation. As a result, due to decreased drinking water consumption and decreased food consumption during the later stages of lactation, it is not possible to exclude secondary effects due to maternal dehydration and reduced nursing that may have influenced pup weight on PND 21. Because the effects reported could be related to decreased maternal fluid the utility of this study for risk assessment is limited.

Further, reproductive toxicity induced by aluminium chloride was investigated by Dixon (Dixon et al., 1979). Groups of 31 males were exposed daily to 5, 50 and 500 mg Al/L drinking water over a time period of 90 days which corresponds to an anticipated absorbed dose of 0.005, 0.05 and 0.5 mg Al/kg bw/day. No apparent effects on male reproductive performance were determined as detected by plasma gonadotropin levels and serial matings. Hormonal levels of FSH and LH, the number of implantation sites and the average litter size was comparable among the groups. Further, histopathology of parent male animals showed no compound-induced abnormalities in the reproductive capacity of males. Therefore, a NOAEL ≥ 0.5 mg Al/kg bw/day as anticipated absorbed dose was defined for fertility.

The toxicity to reproduction of docosanoic acid (CAS 112-85-6) was evaluated in a GLP-conducted combined repeated dose and reproductive/developmental toxicity screening test according to OECD Guideline 422 (Nagao et al., 2002). The study included groups of 13 male and female Sprague-Dawley rats which received 100, 300 and 1000 mg/kg bw/day docosanoic acid daily by gavage. Males were treated for 42 days including two weeks prior to mating, the mating period and two weeks post mating. Females were exposed over a time period of approx. 50 days covering the period of 14 days prior to mating until Day 3 of lactation. In parental animals, neither mortality nor abnormalities in general condition were observed. Moreover, the number of corpora lutea, implantation rate, number of implantations and all other reproductive parameters including sperm parameters, reproductive indices (copulation, fertility and gestation index) were comparable among the groups. Thus, the NOAEL for toxicity to reproduction was defined as ≥ 1000 mg/kg bw/day.

 

In summary, toxicity to reproduction, i.e. effects on fertility, of the first dissociation product aluminium was evaluated based on a two generation study according to OECD 416 (Hirata-Koizumi et al., 2011) and with a subchronic reproductive toxicity study (Dixon et al., 1977), in which fertility of parental animals was unaffected by aluminium ingestion. The potential for reproductive toxicity of fatty acids as second dissociation product was evaluated based on the reproductive / developmental toxicity screening test according to OECD Guideline 422 (Nagao et al., 2002). As fatty acids in general exhibit only low systemic toxicity as determined for several fatty acids (HERA, 2002), the reproductive/developmental screening study performed with docosanoic acid is considered to sufficiently prove low hazard of fatty acids for reproductive toxicity.

In conclusion, the dissociation products ofFatty acids, C16-18 (even numbered), aluminum salt, are not considered to induce effects on fertility. Based on these data, Fatty acids, C16-18 (even numbered), aluminum salt is not considered to possess reproductive activity.

 

References not included in IUCLID:

ATSDR (Agency for Toxic Substances and Disease Registry) (2008).Toxicological Profile for Aluminum.Atlanta: Department of Health and Human Services, Public Health Service.

CIR (1987). Final report on the safety assessment of oleic acid, lauric acid, palmitic acid, myristic acid, stearic acid. J. of the Am. Coll. of Toxicol.6 (3): 321-401

Ganrot, P.O. (1986). Metabolism and possible health effects of aluminum. Environ Health Perspect 65:363-441.   

Krewski et al. (2007). Human Heaklth Risk Assessment for Aluminium, Aluminium Oxide, and Aluminium Hydroxide. J Toxicol Environ Heakth B Crit Rev 10(1):1-269

U.S. High Production Volume (HPV) Chemical Challenge Program (2007)

 

 

Short description of key information:
NOAEL (fertility, rat): ≥ 367.1 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day (based on a worst case assumption of up to 8.5% aluminium) (OECD 416, GLP, Hirata-Koizumi et al., 2011)
LOAEL (parental toxicity, rat): 367.1 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day (based on a worst case assumption of up to 8.5% aluminium) (OECD 416, GLP, Hirata-Koizumi et al., 2011)

Justification for selection of Effect on fertility via oral route:
No study was selected as hazard assessment was conducted by a weight of evidence of read-across from structural surrogates of dissociation products. The selected key studies are the most adequate and reliable studies based on exposure period and similarities in structure and intrinsic properties between the source and dissociation products of the target substance. The most sensitive effet level was chosen for the key information.

Effects on developmental toxicity

Description of key information

NOAEL (developmental toxicity, rat): ≥ 1564.7 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day (based on a worst case assumption of up to 8.5% aluminium) (Gomez, 1991)
NOAEL (parental toxicity, rat): ≥ 1564.7 mg Fatty acids, C16-18 (even numbered), aluminum salt/kg bw/day (based on a worst case assumption of up to 8.5% aluminium) (Gomez, 1991)

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from reference substances with similar structure and intrinsic properties of dissociation products of the target substance. Read-across is justified based on dissociation products (refer to endpoint discussion for further details). The selected studies are thus sufficient to fulfil the standard information requirements set out in Annex VII, 8.5, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Developmental toxicity

No studies are available on developmental toxicity of Fatty acids, C16-18 (even numbered), aluminum salt. However, there are reliable data on analogue substances which are considered suitable for read-across. According to the general rules defined in Regulation (EC) No. 1907/2006, Annex XI, Item 1.5 for the grouping of substances and read-across approach, similarities between substances may be based on “common functional groups” and “common precursors and/or the likelihood of common breakdown products via physical and biological processes, which result in structurally similar chemicals”. Bonds between metal salts and carboxylic acids are known to readily dissociate into the corresponding metal and carboxylic acid in the ambient environment (at neutral pH) and in the digestive tract (at low pH) where complete dissociation occurs, as determined for aluminium di- and tristearate in the US HPV Chemical Challenge Program (2007). Thus, nearly complete dissociation of aluminum fatty acid salts into aluminium, stearic (C18) and/or palmitic (C16) acid is expected to occur in the digestive tract after oral ingestion thereby indicating that toxicity of Fatty acids, C16-18 (even numbered), aluminum salt can be evaluated based on reliable data for the dissociation products and structural analogues of those. The first dissociation product, C16 and 18 fatty acids are stepwise degraded within the mitochondrium matrix by β (–) Oxidation in which C2 units are released (CIR, 1987). Therefore, read-across to saturated fatty acids of different chain length is feasible because of the likelihood of common breakdown products. The second dissociation product,aluminium exists in 4 different forms in the living organisms, including free ions, low-molecular-weight complexes, physically bound macromolecular complexes, and covalently bound macromolecular complexes (Ganrot 1986). As the pathways leading to toxic outcomes are mainly dominated by the chemistry and biochemistry of the aluminium ion (Al³⁺) (Krewski et al., 2007; ATSDR, 2008), different aluminium compounds may serve as surrogates for read-across to the free metal component ofFatty acids, C16-18 (even numbered), aluminum salt.

As noted in Regulation (EC) No. 1907/2006, Article 13 (1) "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.” Information shall therefore be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related or surrogate substances (grouping or read-across) “to avoid the need to test every substance for every endpoint”. For details on the read-across approach please refer to the analogue justification in section 13 of the technical dossier.

As no data are available on developmental toxicity ofFatty acids, C16-18 (even numbered), aluminum salts, read-across to reliable data on the analogue and surrogate substances octanoic acid (CAS 124-07-2), aluminium chloride (CAS 7446-70-0) and aluminium citrate (CAS 31442-56-0) was performed.

Developmental toxicity of octanoic acid was analyzed in a Chernoff/Kavlock developmental toxicity assay (Narotsky et al., 1994). Groups of 16 Sprague-Dawley rats were exposed to 1125 and 1500 mg octanoic acid/kg bw/day from Day 6 – 15 of gestation via gavage. Maternal mortality rates of 31 and 44% were observed in the low-and high-dose groups, which most possibly included some deaths attributed to intubation error. However, respiratory effects like rale and dyspnea in addition to reduced body weights observed in dams might point to maternal toxicity in the applied doses. In pups, no teratogenic effects were observed. The number of live pups was significantly reduced in the high-dose group on PND 6. As dams in this dose group showed severe peripartum respiratory symptoms, the decreased viability of pups might be due to maternal toxicity. Based on these findings, the NOAEL for maternal toxicity was set at 1125 mg/kg bw/day and for teratogenicity and developmental toxicity at 1500 mg/kg bw/day.

 

The combined repeated dose and reproductive/developmental toxicity screening test performed by Nagao et al. according to OECD Guideline 422 confirms the low developmental toxicity of fatty acids as a NOAEL ≥ 1000 mg/kg bw/day, corresponding to the highest-dose tested, was derived for maternal and developmental toxicity of docosanoic acid (Nagao et al., 2002).

 

No reproductive effects were observed in female Sprague-Dawley rats exposed to 133 mg Al/kg bw/day as aluminium citrate by gavage from gestation day 6 to 12 (Gomez et al. 1991). Briefly, number of corpora lutea, implantation sites and preimplantation loss were comparable among the test and control group. Furthermore, no differences in the number of viable or nonviable implants per litter, percentage of post-implantation loss and sex ratio were determined. Visceral and skeletal analyses did not show any treatment-related effect. Tissue analysis showed increased aluminium levels in liver, bone, and placenta in the test group. Therefore, a NOAEL ≥ 133 mg Al/kg bw/day was defined for maternal and developmental toxicity corresponding to a NOAEL ≥ 1564.7 mg Fatty acids, C16-18 (even numbered), aluminum salt /kg bw/day (worst case assumption based on a content of up to 8.5% aluminium).

 

Benett et al. (1975) exposed groups of 6 - 10 Holtzman rats intraperitoneally daily for 5 consecutive days during gestation (GD 9 - 13 or 14 - 18) to 40, 75, 100 and 200 mg aluminium chloride/kg bw/day corresponding to 8.1, 15.2, 20.2 and 40.4 mg Al/kg bw/day (Benett et al. 1975). Mortality occurred during the study period in the mid- and high-dose group dams. Autopsy revealed abundant ascites, extensive adhesions between organs and perihepatic granulomas. Moreover, body weight gain of dams was decreased in the treatment groups compared to controls reaching statistical significance for the low- and mid-dose group exposed on GD 14 - 18. As no dose-dependency was observed, the biological significance of this effect remains questionable. In the liver of maternal animals, centrilobular necrosis visible by degeneration and destruction of liver cells around the central vein was observed in histology. In pups, decreased body weights were determined in all groups being significantly lower in the low- (treated on GD 9 - 13) and high-dose group (treated on GD 9 - 13/14 - 18). Further, the mean crown-rump length was significantly lower in fetuses from the low- and high-dose group compared to controls. The incidence of resorptions was found to be significantly higher in all dose groups without dose-dependency (2 - 5, 17, 10 and 37% for control, low-, mid- and high-dose dams). A high incidence of dead offspring was recovered from the high- dose group treated on GD 9 - 13. However, as all dead fetuses were recovered from only one litter, an incidental mortality cannot be excluded. The number of dead offspring from the other treatment groups did not significantly differ from controls. As gross abnormalities were detected in fetuses of the mid- and the control group (treated on GD 14 - 18), a treatment-related effect is excluded. A high incidence of abnormal fetuses was found in the mid-dose group (treated on GD 14 - 18) including 3 fetuses from 2 litters with abnormal digits, 7 fetuses from 4 litters with wavy ribs and missing ribs in some cases. As no dose-response relationship was present, adversity of this effect is questionable. A large number of fetuses from test animals showed poor ossification particularly in the cranial bone, the lower part of the vertebral column as well as the long bones of the limbs. Kidneys and livers of fetuses in addition to placenta appeared normal in all test groups. A NOAEL of 8.1 mg/kg bw/day was defined for maternal toxicity based on the occurrence of mortality in the mid – and high-dose group. The relevance of the study for assessment of developmental/teratogenic effects is limited due to the exposure route (intraperitoneal). Moreover, the small number of dams of only 6 - 10 animals complicates the discrimination of adverse and incidental effects.

In summary, available and reliable developmental toxicity studies do not provide evidence that the dissociation products of Fatty acids, C16-18 (even numbered), aluminum salt, induce developmental toxicity. Thus, the data indicate a low potential of Fatty acids, C16-18 (even numbered), aluminum salt for developmental toxicity.   

 

References not included in IUCLID:

ATSDR (Agency for Toxic Substances and Disease Registry) (2008).Toxicological Profile for Aluminum.Atlanta: Department of Health and Human Services, Public Health Service.

CIR (1987). Final report on the safety assessment of oleic acid, lauric acid, palmitic acid, myristic acid, stearic acid. J. of the Am. Coll. of Toxicol.6 (3): 321-401

Ganrot, P.O. (1986). Metabolism and possible health effects of aluminum. Environ Health Perspect 65:363-441.   

Krewski et al. (2007). Human Heaklth Risk Assessment for Aluminium, Aluminium Oxide, and Aluminium Hydroxide. J Toxicol Environ Heakth B Crit Rev 10(1):1-269

U.S. High Production Volume (HPV) Chemical Challenge Program (2007)

 

 

Justification for selection of Effect on developmental toxicity: via oral route:
No study was selected as hazard assessment was conducted by a weight of evidence of read-across from structural surrogates of dissociation products. The selected key studies are the most adequate and reliable studies based on exposure period and similarities in structure and intrinsic properties between the source and dissociation products of the target substance. The most sensitive effet level was chosen for the key information.

Justification for classification or non-classification

The available data on toxicity to reproduction do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.