Developmental Toxicity Study In Rats Research Articles

Prenatal developmental toxicity studies of allyl alcohol in rats and rabbits

Allyl alcohol (C3H6O; prop-2-en-1-ol; CAS RN 107-18-6; EINECS 203-470-7) is used as an intermediate/monomer in polymerization reactions producing chemicals/optical resins or as a coupling/cross-linking agent for unsaturated polyester and alkyd resins. Human exposure to allyl alcohol (AA) is restricted to workplace manufacturing facilities where it is used in enclosed systems, which limits release and impact on environmental receptors. To address regulatory questions about possible developmental toxicity, two OECD Guideline studies were conducted. A rat developmental toxicity study found fetal and maternal toxicity, in the form of resorptions and decreased body weight and food consumption, but no teratogenic effects. A rabbit developmental toxicity study was subsequently conducted upon request by the European Chemical Agency in 2011 under the REACH program and likewise reported maternal toxicity in the form of reductions in body weight gain and food consumption, but neither fetal toxicity or teratogenic effects. The results of both studies are presented and compared in this paper. Based on our review of the collective results of these studies, AA is considered non-teratogenic, yet does elicit increased post-implantation loss and reduced fetal body weight, possibly resulting from concomitant maternal toxicity. Based on the results of these studies, a maternal and developmental toxicity No Observed Adverse Effect Level of 10 mg/kg/day was apparent for both species.

Risk Assessment of the Growth Inhibitor Bonzi with the Active Substance Paclobutrazol

Bonzi is a new plant growth regulator containing the active ingredient paclobutrazol of the triazole chemical class. Bonzi is for use on ornamental plants, such as Chrysanthemum, Perennial Plants, Bedding Plants, Foliage Plants, Geraniums, Hibiscus and Azaleas, in nurseries and greenhouses.
 
 VKM was requested by the Norwegian Food Safety Authority to consider the potential of Bonzi and paclobutrazol to induce reproductive effects in humans; in particular the relative sensitivity and relation between maternal effects and the effects on the offspring; and to what extent cleft palate observed in developmental studies in rat can be regarded as a specific teratogenic effect of relevance for humans. The risk assessment was finalized in a meeting in VKM’s Scientific Panel on Plant Protection Products on May 24. 2013.
 VKM’s conclusions are as follows:
 
 No adverse effect on fertility or reproductive performance was seen in rats. VKM concluded that the incidences of twisted snout observed in the F1 and F2 offspring of paclobutrazol treated rats are not likely to represent a developmental alteration, but rather an unspecific toxic effect.
 
 Marked maternal toxicity was seen in rats above 250 mg/kg bw/day, while partially ossified 7th cervical transverse processes and supernumerary 14th ribs were found in the offspring at 10 - 40 mg/kg/day. VKM concluded that the latter should be regarded as a direct teratogenic effect of paclobutrazol.
 
 Furthermore, VKM concluded that the data from the developmental toxicity studies are inconclusive regarding the effect on cleft palate development in rat foetuses.
 
 VKM proposes a NOAEL of 2.5 mg/kg bw/day for paclobutrazol based on a developmental toxicity study in rats.

Re-Assessment of the Plant Protection Product PROMAN – with the Active Ingredient Metobromuron [Edition 2

Proman is a broad spectrum selective herbicide for potatoes grown outdoors, containing the active substance metobromuron. VKM’s Panel on Plant Protection Products has previously discussed questions concerning Proman raised by The Norwegian Food Safety Authority, and stated its opinion in a report of 21. January 2015 (http://www.vkm.no/dav/3c64afe035.pdf). 
 Following this report, The Norwegian Food Safety Authority turned down the application to register Proman as a plant protection product in Norway. The applicant filed a complaint on this decision, and the VKM Panel has been asked to reassess its previous opinion in light of the information given by the applicant in the complaint. 
 The VKM Panel has discussed the arguments put forward in the complaint. The arguments did not change the Panel’s main conclusions in the original assessment. Some changes in the wording of the conclusions were however done, in order to put more emphasis on areas of uncertainty. 
 These are the standing conclusions of VKM’s Panel on Plant Protection Products:
 
 On the relevance of the carcinogenic effects observed in the rat carcinogenicity study; fibrosarcomas in females and pheochromocytomas and Leydig cell tumours in males: 
 It is the opinion of VKM’s Panel for Plant Protection Products that the relevance of the observed incidences of mammary gland tumours and Leydig cell tumours in the rat carcinogenicity study is strengthened by the fact that the increases in tumours associated with exposure to metobromuron are observed in hormone responsive tissues. The panel concludes that the carcinogenic effects observed in the rat carcinogenicity study could be relevant for tumour induction in humans. 
 Higher incidences of still dumbbell-shaped centres of thoracic vertebrae and nonossification of the 13th rib observed in the rat developmental toxicity study and whether these are considered to be malformations: 
 VKM’s Panel on Plant Protection Products has discussed the classification of the different types of incomplete ossifications and concluded that incomplete ossification of sternebrae and non-ossification of the 13th rib in rats should by itself be considered to be variations, and not adverse developmental effects. On the other hand, the Panel agrees with ECHA that the “thoracic vertebral centres still dumbbell-shaped” should be considered as malformations, due to limited data and understanding of the mechanism underlying the observed slow reversal of these anomalies. Furthermore, it is the view of the Panel that the different types of retarded ossification induced by the exposure should be considered as a whole when assessing for developmental effects. 
 Establishment of the NOAEL for the developmental toxicity study in rats and the reference value (ARfD): 
 VKM’s Panel on Plant Protection Products supports the proposal of an ADI value of 0.008 mg/kg bw/day based on a NOAEL of 0.8 mg/kg bw/day from the 2-year study in mouse, and AOEL of 0.016 mg/kg bw/day based on the NOAEL of 1.6 mg/kg bw/day from the 1-year feeding study in dog. The panel suggests an alternative ARfD value of 0.03 mg/kg bw based on a LOAEL of 10 mg/kg bw /day for the observations of incomplete ossification in the rat developmental study. 
 The anti-androgenic potential of metobromuron: 
 The rat carcinogenicity study indicates that metobromuron may interact with the endocrine system. The data from the Hershberger in vivo rat study, the in vitro studies, as well as the comparison with demonstrated effects and mechanisms for flutamide and linuron is suggestive of an anti-androgenic effect. Thus, it is the opinion of the VKM Panel on Plant Protection Products that an anti-androgenic effect of metobromuron cannot be excluded.

Quantitative in vitro to in vivo extrapolation for developmental toxicity potency of valproic acid analogues.

The developmental toxicity potential (dTP) concentration from the devTOX quickPredict (devTOXqP ) assay, a metabolomics-based human induced pluripotent stem cell assay, predicts a chemical's developmental toxicity potency. Here, in vitro to in vivo extrapolation (IVIVE) approaches were applied to address whether the devTOXqP assay could quantitatively predict in vivo developmental toxicity lowest effect levels (LELs) for the prototypical teratogen valproic acid (VPA) and a group of structural analogues. VPA and a series of structural analogues were tested with the devTOXqP assay to determine dTP concentration and we estimated the equivalent administered doses (EADs) that would lead to plasma concentrations equivalent to the in vitro dTP concentrations. The EADs were compared to the LELs in rat developmental toxicity studies, human clinical doses, and EADs reported using other in vitro assays. To evaluate the impact of different pharmacokinetic (PK) models on IVIVE outcomes, we compared EADs predicted using various open-source and commercially available PK and physiologically based PK (PBPK) models. To evaluate the effect of in vitro kinetics, an equilibrium distribution model was applied to translate dTP concentrations to free medium concentrations before subsequent IVIVE analyses. The EAD estimates for the VPA analogues based on different PK/PBPK models were quantitatively similar to in vivo data from both rats and humans, where available, and the derived rank order of the chemicals was consistent with observed in vivo developmental toxicity. Different models were identified that provided accurate predictions for rat prenatal LELs and conservative estimates of human safe exposure. The impact of in vitro kinetics on EAD estimates is chemical-dependent. EADs from this study were within range of predicted doses from other in vitro and model organism data. This study highlights the importance of pharmacokinetic considerations when using in vitro assays and demonstrates the utility of the devTOXqP human stem cell-based platform to quantitatively assess a chemical's developmental toxicity potency.

Safety evaluation of long-chain glycolipids from Dacryopinax spathularia.

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of long‐chain glycolipids from Dacryopinax spathularia (also called AM‐1) as a food additive. AM‐1 is a purified mixture of long‐chain glycolipid congeners obtained by fermentation of the edible non‐genetically modified fungus Dacryopinax spathularia. AM‐1 glycolipids have very low oral bioavailability and overall available toxicology data do not demonstrate any adverse effects of the proposed food additive. Considering the available data set the Panel established an ADI of 10 mg/kg bw per day based on a range of NOAELs between 1,000 and 1,423 mg/kg bw per day (the highest doses tested), from the reproductive and a prenatal developmental toxicity studies in rats and 90‐day studies in rat and dog. At the proposed maximum use levels, the exposure estimates ranged at the mean from 0.01 to 1.07 mg/kg bw per day and at the p95 from 0 to 3.1 mg/kg mg/kg bw per day. At the proposed typical use levels, the exposure estimates ranged at the mean from < 0.01 mg/kg bw per day to 0.23 mg/kg bw per day and at the p95 from 0 to 0.64 mg/kg bw per day. The Panel noted that the highest estimate of exposure of 3.1 mg/kg bw per day (in toddlers) is within the established ADI of 10 mg/kg bw per day and concluded that the exposure to long‐chain glycolipids from Dacryopinax spathularia does not raise a safety concern at the uses and use levels proposed by the applicant.

Risk Assessment of the Plant Protection Product PROMAN – with the Active Ingredient Metobromuron

Proman is a new product containing the active substance metobromuron. The intended use is as a broad spectrum selective herbicide for potatoes grown outdoors.&#x0D; VKM’s Panel on Plant Protection Products has discussed the questions raised by The Norwegian Food Safety Authority in the Terms of reference and has stated the following opinion:&#x0D; On the relevance of the carcinogenic effects observed in the rat carcinogenicity study; fibrosarcomas in females and pheochromocytomas and Leydig cell tumours in males:&#x0D; It is the opinion of VKM’s Panel for Plant Protection Products that the relevance of the observed incidence in mammary gland tumours and Leydig cell tumours in the rat carcinogenicity study is strengthened by the fact that the tumours are observed in hormone responsive tissues. The panel concludes that the carcinogenic effects observed in the rat carcinogenicity study are likely to be relevant for tumours that are influenced by the endocrine system, also in humans.&#x0D; On the higher incidences of still dumbbell-shaped centres of thoracic vertebrae and nonossification of the 13th rib observed in the rat developmental toxicity study and whether these are considered to be malformations:&#x0D; VKM’s Panel on Plant Protection Products has discussed the classification of the different types of incomplete ossifications and concluded that incomplete ossification of sternebrae and non-ossification of the 13th rib in rats should by itself be considered to be variations, and not adverse developmental effects. On the other hand, the Panel agrees with ECHA that the “thoracic vertebral centres still dumbbell-shaped” should be considered as malformations, due to limited data and understanding of the mechanism underlying the observed slow reversal of these anomalies. Furthermore, it is the view of the Panel that the different types of retarded ossification induced by the exposure of metobromuron should be considered as a whole when assessing for developmental effects.&#x0D; On the establishment of the NOAEL for the developmental toxicity study in rats and the reference value (ARfD):&#x0D; VKM’s Panel on Plant Protection Products supports the proposal of an ADI value of 0.008 mg/kg bw/day based on a NOAEL of 0.8 mg/kg bw/day from the 2-year study in mouse, and VKM Report 2015: 03 5.&#x0D; AOEL of 0.016 mg/kg bw/day based on the NOAEL of 1.6 mg/kg bw/day from the 1-year feeding study in dog. An UF of 100 is applied. The panel suggests on the other hand an ARfD of 0.03 mg/kg bw based on a LOAEL of 10 mg/kg bw /day with the observations of incomplete ossification in the rat developmental study. An UF of 300 is applied.&#x0D; On the possible anti-androgenic potential of metobromuron:&#x0D; It is the view of the Panel that the rat carcinogenicity study suggests that metobromuron may possess endocrine disrupting potency. The data from the Hershberger in vivo rat study and the in vitro studies is also suggestive of a weak anti-androgenic effect. Thus, it is the opinion of the VKM Panel on Plant Protection Products that an anti-androgenic effect of metobromuron cannot be excluded.

Safety of nicotinamide riboside chloride as a novel food pursuant to Regulation (EU) 2015/2283 and bioavailability of nicotinamide from this source, in the context of Directive 2002/46/EC.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Allergens (NDA) was asked to deliver an opinion on nicotinamide riboside chloride as a novel food (NF) pursuant to Regulation (EU) 2015/2283, including an evaluation of the safety of its use in food supplements as a source of niacin, and the bioavailability of nicotinamide from this source, in the context of Directive 2002/46/EC. The NF, a synthetic form of nicotinamide riboside, is proposed to be used in food supplements for the healthy adult population at levels up to 300 mg/day. The production process, composition, specifications, batch‐to‐batch variability and stability of the NF do not raise safety concerns. Animal and human data indicate that the NF contributes to the nicotinamide body pool. There are no concerns regarding genotoxicity. Human studies do not raise safety concerns. The proposed maximum use level corresponds to an amount of nicotinamide, which is sixfold lower than the tolerable upper intake level (UL) set for adults, excluding pregnant and lactating women. The margin of exposure (MoE) of 70 derived from repeated dose toxicity studies with rats and dogs is considered sufficient for the adult population, excluding pregnant and lactating women. Regarding these two population groups, the MoE of 76 derived from a developmental toxicity study in rats is considered insufficient in the absence of data which could justify accepting a MoE lower than 100. The Panel concludes that the NF is safe under the proposed conditions of use for the healthy adult population, excluding pregnant and lactating women, and that an intake of the NF up to 230 mg/day is safe for pregnant and lactating women. The Panel also concludes that the NF is a source from which nicotinamide, a form of niacin, is bioavailable.

Re‐evaluation of hydrochloric acid (E 507), potassium chloride (E 508), calcium chloride (E 509) and magnesium chloride (E 511) as food additives

The Panel on Food Additives and Flavourings added to Food (FAF) provided a scientific opinion re‐evaluating the safety of chlorides (E 507–509, E 511) as food additives. Chlorides are authorised food additives in the EU in accordance with Annex II and III to Regulation (EC) No 1333/2008. In the non‐ brand‐loyal scenario, mean exposure to chlorides (E 507–509, E 511) as food additives ranged from 2 mg/kg body weight (bw) per day in the elderly to 42 mg/kg bw per day in toddlers. The 95th percentile of exposure ranged from 5 mg/kg bw per day in the elderly to 71 mg/kg bw per day in toddlers. Chloride is an essential nutrient and after absorption is distributed to organs and tissues. The Panel considered chlorides to be of low acute oral toxicity and there is no concern with respect to genotoxicity and carcinogenicity. No effects were reported in developmental toxicity studies in rats following administration of magnesium chloride hexahydrate at 800 mg/kg bw per day. Some animal studies suggested a role of chloride in increasing blood pressure but based on the toxicological database available the Panel considered human data more appropriate to identify a level of chloride intake which does not raise a safety concern. The Panel identified a human dose of 40 mg chloride/kg bw per day as a reference value for the assessment. Mean levels of exposure in all age groups were below or at this reference value, which indicates no safety concern. In some age groups (toddlers, children and adolescents), the 95th percentile exposure estimates were slightly above this reference value. The Panel concluded that the exposure to chloride from hydrochloric acid and its potassium, calcium and magnesium salts (E 507, E 508, E 509 and E 511) does not raise a safety concern at the reported use and use levels.

Innovative selection approach for a new antifungal agent mefentrifluconazole (Revysol®) and the impact upon its toxicity profile

Mefentrifluconazole (trade name: Revysol®) is an agrochemical active ingredient from the new sub-class of isopropanol-triazole fungicides, with high selective fungicide activity. A full program of toxicity testing conducted according to OECD guidelines has shown mefentrifluconazole (MFZ) to be non-genotoxic and non-carcinogenic. Repeated dose studies in rats, mice and dogs identified the liver as the main target organ. Prenatal developmental toxicity studies in rats and rabbits did not indicate treatment-related embryofetal toxicity or teratogenicity up to the highest dose levels tested. In a two-generation dietary study in rats, the high dose level resulted in reduced food consumption and body weight gain throughout the dosing-period. Mating performance and fertility, estrous cycles, gestation length and pre-and post-natal survival of offspring were essentially unaffected and there was no evidence of masculinization of female pups or feminization of male pups. The screening strategy that led to the selection of MFZ was aimed to identify candidates with both high fungicidal activity and minimal likelihood of adverse side effects thought to arise from aromatase inhibition. The success of the selection strategy has been illustrated for MFZ by the absence in toxicity studies of effects that would indicate an endocrine disrupting potential.

Aluminium Ammonium Sulfate and Aluminium Potassium Sulfate (Food Additives).

Food Safety Commission of Japan (FSCJ) conducted a risk assessment of aluminium ammonium sulfate and aluminium potassium sulfate. This evaluation was requested from Ministry of Health, Labour and Welfare (MHLW) to revise the standards for use of additives. Aluminium ammonium sulfate and aluminium potassium sulfate as additives are assumed reasonably to behave as ions after dissociation, such as aluminium, ammonium, potassium, and sulfate ions, in digestive tract prior to their absorption. FSCJ thus evaluated the safety of aluminium ammonium sulfate and aluminium potassium sulfate used as additives, in considering the substances that are composed of ammonium ion, sulfate ion, potassium ion and aluminium ion. FSCJ concluded that there were no safety concerns of sulfate, ammonium and potassium ions as the use of aluminium ammonium sulfate and aluminium potassium sulfate for food additives. FSCJ specified the lowest no-observed-adverse-effect level (NOAEL) of 30 mg/kg bw/day for aluminium ion based on the reproductive developmental toxicity studies in rats. FSCJ also recognized no carcinogenicity of aluminium additives. FSCJ judged no clear relationship of dietary intake of aluminium with the influences on the bone, mainly due to the insufficient amounts of evidence. FSCJ judged no sufficient evidence to indicate a causal relationship between dietary intake of aluminium and neurological diseases including Alzheimer’s disease. FSCJ confirmed that no human data exist to indicate the clear association of the dietary intake with human health effects of aluminium. FSCJ specified this metal (Al) to be 1.0 mg/kg bw/week for the children (1 to 6 years) and 0.57 mg/kg bw/week for the general population. A safety factor of 100 was applied to the NOAEL of 30 mg/kg bw/day obtained in a developmental toxicity study in rats. Converting the value thus obtained to the aluminium intake per a week, FSCJ established a tolerable weekly intake (TWI) of 2.1 mg/kg bw/week (as Al) for aluminium.

Induction of a thoracolumbar supernumerary rib in rat developmental toxicity studies: A short discussion on the critical window.

Thoracolumbar supernumerary ribs (TSRs) are classified as less severe skeletal anomalies in rat developmental toxicity studies, although their incidence is relatively high in rodent studies. To investigate the characteristics of the critical window for chemically-induced TSR, in this study, rats were administered 5-fluorocytocine (5-FC) or sodium salicylate (SAL) at one of three time periods on gestational day (GD) 9, early morning (7:00 am), midday (12:00 pm to 1:00 pm), or late afternoon (4:00 pm or 7:00 pm). The incidence of TSR and other anomalies were assessed in GD20 fetuses. A single treatment with both chemicals on GD9-induced TSR, with the incidence highest when administered at 7:00 Am, decreasing gradually when administered later. This trajectory was clearer in rats treated with 5-FC than with SAL. The critical period of TSR induction is shorter in rats administered 5-FC than SAL. The characteristics of the critical window may cause variability in the incidence of TSR observed in developmental toxicity studies.

Repeated dose inhalation developmental toxicity study in rats exposed to cellulose insulation with boric acid additive

Cellulose insulation (CI), a common building material, is a mixture of cellulose fibers and borates. Borates are approximately 20% of the product weight and act as a flame retardant. Given possible exposure to workers and consumers, an inhalation toxicity study was conducted following Organization for Economic Co-operation and Development (OECD) 414 for Prenatal Development Toxicity to evaluate if CI is a developmental toxicant. Pregnant female rats were exposed by nose-only inhalation to CI aerosols containing 20% boric acid for six h/day, from gestational day (GD) 6–19, and fetuses were evaluated for developmental parameters. Respirable CI was produced by grinding to produce respirable particles (MMAD 2.7–2.9 µm, geometric standard deviations (GSD) 1.9–2.6), which were then aerosolized. Target air concentrations were 15, 90, and 270 mg CI/m3. Controls were exposed to air only. Slight body weight reductions (average decrease <7% vs. control) were observed in male and female GD 20 fetuses in the mid and high dose groups. No embryo/fetal developmental toxicity or alterations in any other measured variable were reported at any dose. The no observed adverse effect level (NOAEL) for developmental outcomes was 270 mg/m3.

Historical control data on developmental toxicity studies in rats.

Historical control data from prenatal developmental toxicity studies in rats have been used to evaluate whether toxicology outcomes were induced by exposure to a chemical or were within the range of spontaneous variation. These data are also important for monitoring animal characteristics. As a follow-up to historical control data from 1998 to 2010, this study analyzed control data from prenatal developmental studies performed in rats from 2011 to 2015. Data were collected from studies performed by 24 Japanese laboratories, including 15 pharmaceutical and chemical companies and nine contract research organizations, in Sprague-Dawley and two-sub-strains of Wistar Hannover rats. The data included maternal reproductive findings at terminal cesarean section and fetal findings, including incidences of spontaneous external, visceral, and skeletal anomalies. No noticeable differences in maternal reproductive data were observed among laboratories. The inter-laboratory variations in the incidences of fetal anomalies seemed to be due to differences in the selection of observation parameters, observation criteria, and classification of the findings, as well as to differences in terminology of fetal alterations. These historical control data may be helpful for adequate interpretation of experimental results and for evaluating the reproductive and developmental toxicities of various chemicals.

Desmedipham (Pesticides).

Food Safety Commission of Japan (FSCJ) conducted a risk assessment of desmedipham (CAS No. 13684-56-5), a carbanilate herbicides, based on results from various studies. Major adverse effects of desmedipham were suppressed body weight, hemolytic anemia, methemoglobinemia and follicular cell hypertrophy in thyroid. Neither carcinogenicity, reproductive toxicity, nor genotoxicity relevant to human health was observed on desmedipham. Desmedipham, at the dose with maternal toxicity, caused external anomalies such as mandibular malformation and cleft palate, visceral anomalies such as ventricular septum defect, and skeletal anomalies such as defect of sternum and asymmetric alignment of seternebral hemicentres in developmental toxicity studies in rats. No teratogenetic effects were observed in rabbits. The lowest no-observed-effect level (NOAEL) obtained in all studies was 3.2 mg/kg bw/day in a two-year combined chronic toxicity/carcinogenicity in rats. FSCJ specified an acceptable (ADI) of 0.032 mg/kg bw/day, applying a safety factor of 100 to the NOAEL. The lowest NOAEL for adverse effects elicited by a single oral administration of desmedipham was 90 mg/kg bw/day obtained from the developmental toxicity study in rabbits (the 2nd study in the Table 2). Consequently, FSCJ specified an acute reference dose (ARfD) of 0.9 mg/kg bw applying a safety factor of 100 to the NOAEL.

The value of plasma metabolomics to define maternal toxicity in rat developmental toxicity studies

The value of plasma metabolomics to define maternal toxicity in rat developmental toxicity studies

Signal management in pharmacovigilance and human risk assessment of CpG 7909, integrating embryo-fetal and post-natal developmental toxicity studies in rats and rabbits

The potential reproductive and developmental toxicity of the synthetic oligodeoxynucleotide (ODN) CpG 7909, a component of GSK’s AS15 immunostimulant, was examined in rat and rabbit studies following intermittent intramuscular injections. Previous studies using subcutaneous and intraperitoneal injections in mice, rats and rabbits revealed that CpG ODNs induced developmental effects. To analyze the safety signal, GSK conducted additional animal studies using the intended clinical route of administration. CpG 7909 injections were administered intramuscularly to rats or rabbits 28 and 14days before pairing, on 4 or 5 occasions during gestation, and on lactation day 7. The No Observed Adverse Effect Level for female fertility, embryo-fetal and pre- and post-natal development was 4.2mg/kg in both species, approximately 500-fold higher than the anticipated human dose. In conclusion, the anticipated risk to humans is considered low for sporadic intramuscular exposure to CpG 7909.

Can rat plasma metabolomics help to define maternal toxicity in rat developmental toxicity studies?

Can rat plasma metabolomics help to define maternal toxicity in rat developmental toxicity studies?

Postnatal Evaluation of Cervical Ribs in Control Rats

Cervical ribs in rat fetuses have been widely reported to occur in controls as well as in response to various maternal chemical exposures. However, few evaluations of cervical ribs have been reported in rats postnatally. The available literature has indicated that the postnatal incidences of cervical ribs in control rats are no higher than in perinatal fetuses. In a developmental toxicity study in rats conducted by the inhalation route, a control group of 44 time-mated female rats was exposed to filtered air only from gestation day (GD) 6 to 20, and divided into two cohorts. For one cohort, fetuses were removed from dams by laparohysterectomy for skeletal evaluation on GD 21. The other cohort of dams was permitted to deliver, and adult offspring were euthanized on postnatal day 65 for a subsequent postnatal skeletal evaluation of cervical ribs. The incidence of cervical ribs (mean percentage of affected fetuses or adults per litter) was observed to increase during postnatal development, from 1.0% on GD 21 to 12.7% on postnatal day 65. Further evaluation is ongoing to determine whether these observations were attributable to the inhalation exposure conditions used in this study. These results, while limited to the evaluation of one skeletal alteration in control rats, support the need for additional research into the area of postnatal development of skeletal abnormalities observed in developmental toxicity studies and the relevance of these skeletal observations to human risk assessment. Birth Defects Research 109:1301-1304, 2017. © 2017 Wiley Periodicals, Inc.

Safety assessment of astaxanthin derived from engineered Escherichia coli K-12 using a 13-week repeated dose oral toxicity study and a prenatal developmental toxicity study in rats

Astaxanthin is a natural carotenoid with strong antioxidant activity that has been used for decades as a nutrient/color additive and it has recently been marketed as a health supplement. Astaxanthin can be synthesized in a wide range of microalgae, yeast, and bacteria. As genes directing astaxanthin biosynthesis in various organisms have been cloned, this study assessed the safety of astaxanthin crystal produced by Escherichia coli K-12 harboring plasmids carrying astaxanthin biosynthetic genes. The astaxanthin crystal contains a total carotenoid content of 950 mg/g and an astaxanthin content of 795 mg/g. Subchronic oral toxicity and prenatal developmental toxicity of the astaxanthin in rats were conducted in accordance with the Guidelines of Health Food Safety Assessment promulgated by Food and Drug Administration of Taiwan which is based on OECD guidelines 408 and 414. Both male and female Sprague-Dawley (SD) rats (12 for each gender) receiving the astaxanthin crystal at 1.2, 240.0, or 750.0 mg/kg/day in olive oil via oral gavage for 90 days showed no changes in body weight gains, hematology and serum chemistry values and hepatic enzyme stability, organ integrity and organ weight. Except the higher food consumption observed in rats receiving 750.0 mg/g astaxanthin crystal, administration of the astaxanthin crystal to 25–27 pregnant female rats in each group throughout the period of organogenesis (G6-G15) produced no adverse effects on fetal organogenesis. Based on the results, we propose that the no-observable-adverse-effect level (NOAEL) of the astaxanthin crystal extracted from genetically modified E. coli K-12 is 750.0 mg/kg bw/day.

Prednisolone (Veterinary Medicinal Products).

The Food Safety Commission of Japan (FSCJ) conducted a risk assessment of prednisolone (CAS No. 50-24-8), a steroidal anti-inflammatory agent, using the evaluation reports of EMA (EMEA) and documents for the re-evaluation* of veterinary medicinal products. All the genotoxicity studies in vivo were negative, although some of in vitro genotoxicity studies showed positive results. Prednisolone was thus judged to have no genotoxicity relevant to human health. FSCJ concluded it possible to specify an acceptable daily intake (ADI) of prednisolone. Major adverse effects of prednisolone observed are reduced counts of leukocyte and decreased weighs of the thymus, spleen and adrenal gland. Slight decreases were also observed on bone marrow cells. There is no substantial evidence to suggest the carcinogenicity of prednisolone. Prednisolone treatment resulted in an increased rate of embryonal resorption and a decrease of fetal body weights in a developmental toxicity study in rats. No teratogenicity was observed. FSCJ specified an ADI of 0.00025 mg/kg bw/day (0.25 µg/kg bw/day) for prednisolone applying a safety factor of 1,000 to the LOAEL of 0.25 mg/kg bw/day obtained from the LOAEL of prednisone in 18-month carcinogenicity study in mice.