Developmental and cardiac toxicity assessment of Ethyl 3-(N-butylacetamido) propanoate (EBAAP) in zebrafish embryos.

Ethyl 3-(N-butylacetamido) propanoate (EBAAP) is one of the most widely used mosquito repellents worldwide, and is also commonly used to produce cosmetics. Residues have recently been detected in surface and groundwater in many countries, and their potential to harm the environment is unknown. Therefore, more studies are needed to fully assess the toxicity of EBAAP. This is the first investigation into the developmental toxicity and cardiotoxicity of EBAAP on zebrafish embryos. EBAAP was toxic to zebrafish, with a lethal concentration 50 (LC50) of 140 mg/L at 72 hours post fertilization (hpf). EBAAP exposure also reduced body length, slowed the yolk absorption rate, induced spinal curvature and pericardial edema, decreased heart rate, promoted linear lengthening of the heart, and diminished cardiac pumping ability. The expression of heart developmental-related genes (nkx2.5, myh6, tbx5a, vmhc, gata4, tbx2b) was dysregulated, intracellular oxidative stress increased significantly, the activities of catalase (CAT) and superoxide dismutase (SOD) decreased, and malondialdehyde (MDA) content increased significantly. The expression of apoptosis-related genes (bax/bcl2, p53, caspase9, caspase3) was significantly upregulated. In conclusion, EBAAP induced abnormal morphology and heart defects during the early stages of zebrafish embryo development by potentially inducing the generation and accumulation of reactive oxygen species (ROS) in vivo and activating the oxidative stress response. These events dysregulate the expression of several genes and activate endogenous apoptosis pathways, eventually leading to developmental disorders and heart defects.

RIFM fragrance ingredient safety assessment, citronellyl propionate, CAS registry number 141-14-0.

In addition, the total systemic exposure for citronellyl propionate (0.54 µg/kg/day) is below the TTC (30 µg/kg/day; Kroes, 2007) for the repeated dose toxicity endpoint at the current level of use.

RIFM fragrance ingredient safety assessment, propyl propionate, CAS Registry Number 106-36-5.

The existing information supports the use of this material as described in this safety assessment. Propyl propionate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that propyl propionate is not genotoxic. Data on propyl propionate provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity, reproductive toxicity, and local respiratory toxicity endpoints. Data from read-across analog pentyl propionate (CAS # 624-54-4) show that there are no safety concerns for propyl propionate for skin sensitization under the current declared levels of use. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; propyl propionate is not expected to be phototoxic/photoallergenic. For the hazard assessment based on the screening data, propyl propionate is not persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards. For the risk assessment, propyl propionate was not able to be risk screened as there were no reported volumes of use for either North America or Europe in the 2015 IFRA Survey.

RIFM fragrance ingredient safety assessment, 2,2-dimethyl-3-methyl-3-butenyl propanoate, CAS Registry Number 104468-21-5.

The existing information supports the use of this material as described in this safety assessment. 2,2-Dimethyl-3-methyl-3-butenyl propanoate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog rhodinyl formate (CAS # 141-09-3) show that 2,2-dimethyl-3-methyl-3-butenyl propanoate is not expected to be genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to 2,2-dimethyl-3-methyl-3-butenyl propanoate is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). The skin sensitization endpoint was completed using the dermal sensitization threshold (DST) for non-reactive materials (900 µg/cm2); exposure is below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; 2,2-dimethyl-3-methyl-3-butenyl propanoate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 2,2-dimethyl-3-methyl-3-butenyl propanoate was found not to be persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

RIFM fragrance ingredient safety assessment, ethyl 3-methylthiopropionate, CAS Registry Number 13327-56-5.

The existing information supports the use of this material as described in this safety assessment. Ethyl 3-methylthiopropionate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog methyl 3-methylthiopropionate (CAS # 13532-18-8) show that ethyl 3-methylthiopropionate is not expected to be genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class I material, and the exposure to ethyl 3-methylthiopropionate is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). The skin sensitization endpoint was completed using the Dermal Sensitization Threshold (DST) for non-reactive materials (900 µg/cm2); exposure is below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; ethyl 3-methylthiopropionate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; ethyl 3-methylthiopropionate was found not to be persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current Volume of Use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

Assessment of the Mode of Action Underlying the Effects of GenX in Mouse Liver and Implications for Assessing Human Health Risks.

GenX is an alternative to environmentally persistent long-chain perfluoroalkyl and polyfluoroalkyl substances. Mice exposed to GenX exhibit liver hypertrophy, elevated peroxisomal enzyme activity, and other apical endpoints consistent with peroxisome proliferators. To investigate the potential role of peroxisome proliferator-activated receptor alpha (PPARα) activation in mice, and other molecular signals potentially related to observed liver changes, RNA sequencing was conducted on paraffin-embedded liver sections from a 90-day subchronic toxicity study of GenX conducted in mice. Differentially expressed genes were identified for each treatment group, and gene set enrichment analysis was conducted using gene sets that represent biological processes and known canonical pathways. Peroxisome signaling and fatty acid metabolism were among the most significantly enriched gene sets in both sexes at 0.5 and 5 mg/kg GenX; no pathways were enriched at 0.1 mg/kg. Gene sets specific to the PPARα subtype were significantly enriched. These findings were phenotypically anchored to histopathological changes in the same tissue blocks: hypertrophy, mitoses, and apoptosis. In vitro PPARα transactivation assays indicated that GenX activates mouse PPARα. These results indicate that the liver changes observed in GenX-treated mice occur via a mode of action (MOA) involving PPARα, an important finding for human health risk assessment as this MOA has limited relevance to humans.

RIFM fragrance ingredient safety assessment, isobutyl propionate, CAS Registry Number 540-42-1.

The existing information supports the use of this material as described in this safety assessment. Isobutyl propionate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog isobutyl acetate (CAS # 110-19-0) show that isobutyl propionate is not expected to be genotoxic. Data from read-across analog isoamyl acetate (CAS # 123-92-2) show that there are no safety concerns for isobutyl propionate for skin sensitization under the current declared levels of use. The repeated dose and reproductive endpoints were evaluated using the TTC for a Cramer Class I material, and the exposure to isobutyl propionate is below the TTC (0.03 mg/kg/day and 0.03 mg/kg/day, respectively). For the local respiratory endpoint, a calculated MOE >100 was provided by read-across analog butyl acetate (CAS # 123-86-4). The phototoxicity/photoallergenicity endpoints were evaluated based on UV spectra; isobutyl propionate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; isobutyl propionate is not PBT as per the IFRA Environmental Standards. For the risk assessment, isobutyl propionate was not able to be risk screened as there were no reported volumes of use for North America or Europe in the 2015 IFRA Survey.