Evaluation Of Developmental Toxicity Research Articles

The Toxicological Effects of Heavy Fuel Oil Category Substances

Heavy fuel oil (HFO) category substances are used to manufacture HFO, a product used in industrial boilers and marine diesel engines. Commercial HFOs and blending stream components are substances of complex and variable composition, composed of C20 to >C50 hydrocarbons, although lower molecular weight material may be added to reduce viscosity and improve flow characteristics. An HFO blending stream (catalytically cracked clarified oil [CCCO]) was tested for target organ and developmental toxicity in rats following repeated dermal administration at doses of 5, 25, or 50 mg/kg/d. In the repeated dose study, there was evidence of increased liver weights, reduced thymus weights, and reductions in hematological parameters with an overall no observed adverse effect level (NOAEL) of 5 mg/kg/d. In the developmental toxicity test, there were significant reductions in fetal survival, significant increases in resorption frequency, and significantly reduced fetal weights with an overall NOAEL of 5 mg/kg/d. These target organ and developmental effects are associated with the types and levels of aromatic constituents in these substances. Among HFO blending streams, CCCOs have the highest levels of aromatics and, because they produce the characteristic toxicological effects at the lowest levels, are considered as "reasonable worst-case examples" for this group of substances. Other HFO category members with lower levels of aromatics produce similar effects but have higher NOAELs. The potential for target organ and developmental effects of other HFO category members can be predicted from information on the types and levels of the aromatic constituents present in these substances.

‘Another slice of ovary sir’? Counting corpora lutea indicate that the mouse may not be an appropriate species for evaluation of reproductive and developmental toxicity for human monoclonal antibodies

‘Another slice of ovary sir’? Counting corpora lutea indicate that the mouse may not be an appropriate species for evaluation of reproductive and developmental toxicity for human monoclonal antibodies

In vivo evaluation and comparison of developmental toxicity and teratogenicity of perfluoroalkyl compounds using Xenopus embryos

Perfluoroalkyl compounds (PFCs) are environmental toxicants that persistently accumulate in human blood. Their widespread detection and accumulation in the environment raise concerns about whether these chemicals might be developmental toxicants and teratogens in ecosystem. We evaluated and compared the toxicity of PFCs of containing various numbers of carbon atoms (C8–11 carbons) on vertebrate embryogenesis. We assessed the developmental toxicity and teratogenicity of various PFCs. The toxic effects on Xenopus embryos were evaluated using different methods. We measured teratogenic indices (TIs), and investigated the mechanisms underlying developmental toxicity and teratogenicity by measuring the expression of organ-specific biomarkers such as xPTB (liver), Nkx2.5 (heart), and Cyl18 (intestine). All PFCs that we tested were found to be developmental toxicants and teratogens. Their toxic effects were strengthened with increasing length of the fluorinated carbon chain. Furthermore, we produced evidence showing that perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFuDA) are more potent developmental toxicants and teratogens in an animal model compared to the other PFCs we evaluated [perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA)]. In particular, severe defects resulting from PFDA and PFuDA exposure were observed in the liver and heart, respectively, using whole mount in situ hybridization, real-time PCR, pathologic analysis of the heart, and dissection of the liver. Our studies suggest that most PFCs are developmental toxicants and teratogens, however, compounds that have higher numbers of carbons (i.e., PFDA and PFuDA) exert more potent effects.

Prenatal developmental toxicity study of ethyl tertiary-butyl ether in rats

Ethyl tertiary-butyl ether (ETBE) is commonly used as an oxygenated gasoline additive. In this study, we evaluated its developmental toxicity in rats. ETBE was administered by gavage to 21 or 22 pregnant female Sprague-Dawley rats per group at dose levels of 0, 100, 300 and 1000 mg/kg/day from days 5 through 19 postcoitum to assess its effects on pregnant animals and their embryos and fetuses applied to the OECD testing guideline (no. 414) correspondingly. There were no toxicological effects attributable to ETBE regarding clinical signs, body weight, food intake, necropsy or examination at caesarean section in pregnant animals. There were also no toxicological effects on external, visceral and skeletal examinations of embryos and fetuses. These results indicate that, under the conditions of this study, ETBE had no toxicological effects on pregnant rats or their embryos and fetuses and that the no observed adverse effect level was 1000 mg/kg/day both for pregnant rats and their embryos and fetuses.

The acute, developmental, genetic and inhalation toxicology of 2,3,3,3-tetrafluoropropene (HFO-1234yf)

2,3,3,3-Tetrafluoropropene (HFO-1234yf) is being developed as a refrigerant because it has a very low global warming potential (less than 10), as contrasted to the hydrofluorocarbons, which is intended to replace with values of over 500. Several toxicology studies were conducted to develop a toxicology profile for this material. There was no lethality in mice and rats receiving single 4-hour exposures up to 101 850 or 405 800 ppm, respectively. Additionally, there was no mortality or clinical signs of toxicity when rabbits were exposed to 100 000 ppm for 1 hour. Exposures up to 120 000 ppm did not induce cardiac sensitization to adrenalin in dogs. Rats were exposed to HFO-1234yf at levels of 5000, 20 000 and 50 000 ppm 6 hours/day 5 days/week for 2 weeks and at levels of 5000, 15 000 and 50 000 ppm for 4 weeks and for 90 days. No treatment-related adverse effects were noted in these studies. HFO-1234yf was not genotoxic in a mouse and a rat micronucleus assay, and unscheduled DNA synthesis assay and was not clastogenic in human lymphocytes. HFO-1234yf was mutagenic to Salmonella typhimurium TA 100 and Escherichia coli (WP2 uvrA) at concentrations of 20% and higher in the presence of metabolic activation only. There were no biologically significant effects in a rat developmental toxicity study with exposures up to 50 000 ppm.

Vinclozolin: A case study on the identification of endocrine active substances in the past and a future perspective

In the late 1980s vinclozolin was tested for prenatal developmental toxicity in rats for registration purposes in USA. At 1000mg/kgbw, 95% of all fetuses were female upon visual inspection (ano-genital distance determination). Anti-androgenic effects (AA) were also noted in a subsequent 2-generation study. These findings triggered mechanistic investigations at BASF and at US-EPA. Results published by the latter were the starting point of the endocrine disruption (ED) discussion in the 1990s. AA effects of vinclozolin are mediated by two metabolites, which have an antagonistic effect on the androgen receptor. Currently, determination of ED has become a major end-point in toxicology testing and the US-EPA has set up an elaborated testing paradigm to fulfill this requirement. Future screening for ED can be improved making use of new technologies. ED modes of action can be determined by three alternative (3R) methods. Steroid synthesis in H295R cells (1), androgen-receptor binding in modified yeast (2) and metabolomics (3). Using vinclozolin as a case study, results indicate: (1) an effect on steroid synthesis in vitro, (2) an antagonistic effect on the androgen receptor and (3) that the metabolome profile of vinclozolin is similar to that of other receptor mediated anti-androgens (e.g. flutamide).

Evaluation of E330-induced developmental toxicity using FETAX

The present study evaluates the teratogenic and toxicological effects of citric acid (E330), a food additive, on Xenopus laevis embryos. The embryos were exposed to a range of E330 concentrations, from stage 8 to 11 of development, for 96 h under static renewal test conditions. The median lethal concentrations, no-observed adverse effect concentration (NOAEC), lowest observed adverse effect concentration (LOAEC), and minimum concentration to inhibit growth (MCIG) values were calculated. The lethal concentration (LC) values LC_{10}, LC_{20}, LC_{30}, LC_{40}, and LC_{50} determined for E330 exposure were 0.0113, 0.0117, 0.0119, 0.0122, and 0.0124 g/L, respectively. NOAEC and LOAEC values were calculated as 0.001 and 0.01 g/L. Since the effective concentration (EC_{50}) value could not be determined, the E330 teratogenic index (TI), which is LC_{50}/EC_{50}, was not calculated. MCIG was calculated to be 0.010 g/L. The anomaly rate in Xenopus embryos treated with E330 was quite low. Therefore, the endpoint for the Xenopus embryos was whether they were alive or dead at the end of the study. It can be concluded from these observations that using unlimited amounts of E330 may result in preterm birth or abortion in humans, and E330 usage must be reevaluated and, potentially, limited. Moreover, our results confirm that the Frog Embryo Teratogenesis Assay Xenopus (FETAX) can be a useful pretest for integrated biological hazard assessment.

Evaluation of reproductive and developmental toxicity of multi-wall carbon nanotubes in pregnant mice after tail vein administration

Evaluation of reproductive and developmental toxicity of multi-wall carbon nanotubes in pregnant mice after tail vein administration

Safety assessment of boron by application of new uncertainty factors and their subdivision

The available toxicity information for boron was reevaluated and four appropriate toxicity studies were selected in order to derive a tolerable daily intake (TDI) using newly proposed uncertainty factors (UFs) presented in Hasegawa et al. (2010). No observed adverse effect levels (NOAELs) of 17.5 and 8.8mgB/kg/day for the critical effect of testicular toxicity were found in 2-year rat and dog feeding studies. Also, the 95% lower confidence limit of the benchmark doses for 5% reduction of fetal body weight (BMDL05) was calculated as 44.9 and 10.3mgB/kg/day in mouse and rat developmental toxicity studies, respectively. Measured values available for differences in boron clearance between rats and humans and variability in the glomerular filtration rate (GFR) in pregnant women were used to derive chemical specific UFs. For the remaining uncertainty, newly proposed default UFs, which were derived from the latest applicable information with a probabilistic approach, and their subdivided factors for toxicokinetic and toxicodynamic variability were applied. Finally, overall UFs were calculated as 68 for rat testicular toxicity, 40 for dog testicular toxicity, 247 for mouse developmental toxicity and 78 for rat developmental toxicity. It is concluded that 0.13mgB/kg/day is the most appropriate TDI for boron, based on rat developmental toxicity.

Absence of reproductive and developmental toxicity in rats following exposure to a 20-kHz or 60-kHz magnetic field

The use of intermediate frequency (IF) magnetic fields (MFs) in occupational equipment and domestic appliances, such as inductive heating cookers, is increasing. The WHO indicated a lack of scientific evidence needed to assess the health risk of exposure to IF MFs. Male and female rats (24/group) were exposed to a 20kHz, 0.2mT(rms) or 60kHz, 0.1mT(rms) sinusoidal MF for 22h/day from 14days prior to and during mating. Copulated females were exposed until gestation day 7 and sacrificed thereafter. Mated males were sacrificed to examine MF exposure effects on spermatogenesis. Reproductive examinations were blinded, and experiments were duplicated per frequency to ensure reproducibility. No statistically significant, exposure-related changes were found in the estrous cycle, copulation and fertility indices, numbers of corpora lutea and implantation sites, or pre- and postimplantation loss. No reproducible changes were observed in sperm count, motility, or morphological abnormality, or in the weights of testes and epididymides after MF exposure. No significant abnormalities were observed in gross pathology or histopathology of the uterus, ovary, testis, and epididymis in the MF- or sham-exposed groups. MF exposure during the preimplantation period was not toxic to fertility or early embryogenesis under the experimental conditions.

Evaluation of the Developmental Toxicity of 4-Tert-Butylcyclohexyl Acetate in Sprague-Dawley Rats

The fragrance ingredient 4-tert-butylcyclohexyl acetate (4-tBCHA) was evaluated for potential developmental toxicity in pregnant rats at oral dosages of 0, 40, 160, or 640 mg/kg per d in corn oil on gestational days 7 to 20. Increased salivation was observed at 160 and 640 mg/kg per d. The 640 mg/kg per d dosage was associated with the presence of a red perioral substance, ungroomed, sparse hair coat on the limbs, localized alopecia, reduced feed and body weight gains, or body weight losses, and mortality. Fetal body weights also were reduced at 640 mg/kg per d. This effect was associated with transient delays in fetal development, including significant increases in fetal incidences of moderate enlargement of the renal pelvis and reversible delays in ossification of the caudal vertebrae, fore and hind limb phalanges, and hind limb metatarsals. Maternal and developmental no observable adverse effect levels (NOAELs) were 160 mg/kg per d. It was concluded that 4-tBCHA is not a developmental toxicant in rats.

Developmental toxicity evaluation of ten disinfection by-products on Zebrafish embryos

To assess the potential adverse effects stemming from tetracycline (TC) in drinking water or disinfected wastewater, the kinetics of the chloramination of TC was investigated at room temperature, the transformation products and pathways of their generation were elucidated, and their growth inhibiting properties towards sludge bacteria were assessed. The chloramination of TC exhibited pseudo-first-order kinetics with the rate constants (kobs) ranging from 0.0082 to 0.041 min−1 at pH of 6–8. Chloramination of TC generated at least 13 discernible products, and the structures of 12 products, including five chlorinated compounds, were identified using LC–ESI–MS. Two main pathways for the generation of these products were proposed: (1) chlorine substitution reactions followed by dehydration; and (2) oxidization by chloramine. The chlorinated products were proposed to be further degraded to small molecules via the scission of benzene rings of TC, and two oxidization products (2,11a-dihydroxy-keto-TC and 6,11-epoxy-2,11a-dihydroxy-TC) were the final products obtained under the experimental conditions. The chlorinated solution, even without detection of TC, exhibited greater than 80% of TC inhibitory effects towards sludge bacteria, suggesting potential effects on microorganisms in aquatic environment.

Scientific Opinion on dihydrocapsiate

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a scientific opinion on the safety of a synthetic dihydrocapsiate (DHC) as a food ingredient in the context of Regulation (EC) No 258/97 taking into account the comments and objections of a scientific nature raised by Member States. Dihydrocapsiate belongs to a group known as capsinoids which have been shown to occur naturally in a number of chilli and sweet peppers. The applicant intends to market DHC to food manufacturers as an ingredient for incorporation into foods of various categories at concentration levels varying from 8 to 2050 mg per kg. Considering the proposed uses the mean intake of synthetic DHC was estimated to be around 12–13 mg/day (8.1 mg/day for pre-school children); the 97.5th percentile intakes of adults and the elderly were estimated to be around 34 mg/day (18.5 mg/day for pre-school children). Calculations based on body weights resulted in the highest intakes being for pre-school children (mean: 0.6 mg/kg bw/day; 97.5th percentile: 1.3 mg/kg bw/day). The applicant has provided a range of toxicological studies with DHC. The Panel concludes that it has no safety concerns regarding genotoxicity. Studies on developmental toxicity in rats and rabbits using commercial grade DHC did not show adverse effects on pregnant animals or on foetal growth and development. The no-observed adverse effect level (NOAEL) of three subchronic oral toxicity studies in rats was consistently at 300 mg DHC/kg bw/day. The Panel is of the opinion that the margin of safety (MOS) in relation to the NOAEL of 300 mg/kg bw/day is sufficient, including the highest estimated intake of 1.3 mg/kg bw/day for preschool children. The Panel concludes that the novel food ingredient, DHC, is safe under the proposed uses and use levels.

The threshold of toxicological concern for prenatal developmental toxicity in rabbits and a comparison to TTC values in rats

The Threshold Toxicological Concern (TTC) is based on the concept that reasonable assurance of safety can be given if exposure is sufficiently low. We report on the evaluation of BASF’s data for oral developmental toxicity studies in rabbits with 48 NOAEL values for maternal and developmental toxicity. The 5th percentile of the NOAEL distributions was calculated to be 5mg/kgbw/d for both maternal and developmental toxicity. From literature 56 compounds tested in rabbits were taken and combined with values from BASF’s studies. The 5th percentile value for developmental toxicity of these 104 studies (mostly active ingredients) was 2mg/kgbw/d. Thus, a TTC value of 4μg/kgbw/d was calculated using a safety factor of 500 to account for relatively small database. This value is in the same range as the TTC value for developmental toxicity in rats of 8μg/kgbw/d. The lower value may serve as guidance to determine whether further evaluation is needed or whether to rely on a TTC value for industrial chemicals or low concentration (environmental) contaminants if exposure is sufficiently low. A comparison of 30 compounds tested at BASF in both species, suggests that rabbits are not more sensitive than rats. We encourage others to publish data on rabbit developmental toxicity.

Social housing opportunities during developmental toxicity evaluation in macaques

Social housing opportunities during developmental toxicity evaluation in macaques

A developmental toxicity evaluation comparing Lister Hooded with Wistar Han rats

A developmental toxicity evaluation comparing Lister Hooded with Wistar Han rats

A Novel Mode-of-Action Mediated by the Fetal Muscle Nicotinic Acetylcholine Receptor Resulting in Developmental Toxicity in Rats

Sulfoxaflor (X11422208), a novel agricultural molecule, induced fetal effects (forelimb flexure, hindlimb rotation, and bent clavicle) and neonatal death in rats at high doses (≥ 400 ppm in diet); however, no such effects occurred in rabbit dietary studies despite achieving similar maternal and fetal plasma exposure levels. Mode-of-action (MoA) studies were conducted to test the hypothesis that the effects in rats had a single MoA induced by sulfoxaflor agonism on the fetal rat muscle nicotinic acetylcholine receptor (nAChR). The studies included cross-fostering and critical windows of exposure studies in rats, fetal ((α1)(2)β1γδ) and adult ((α1)(2)β1δε) rat and human muscle nAChR in vitro agonism experiments, and neonatal rat phrenic nerve-hemidiaphragm contracture studies. The weight of evidence from these studies supported a novel MoA where sulfoxaflor is an agonist to the fetal, but not adult, rat muscle nAChR and that prolonged agonism on this receptor in fetal/neonatal rats causes sustained striated muscle contracture resulting in concomitant reduction in muscle responsiveness to physiological nerve stimulation. Fetal effects were inducible with as little as 1 day of exposure at the end of gestation, but were rapidly reversible after birth, consistent with a pharmacological MoA. With respect to human relevance, sulfoxaflor was shown to have no agonism on human fetal or adult muscle nAChRs. Taken together, the data support the hypothesis that the developmental effects of sulfoxaflor in rats are mediated via sustained agonism on the fetal muscle nAChR during late fetal development and are considered not relevant to humans.

Developmental toxicity evaluation of methanol extracts of Carthamus tinctorius L. in the Balb/C pregnant mice during organogenesis period

The plant Carthamus tinctorius L. (Safflower), a member of the compositae is used as a food additive but also has medicinal applications. To assay its effects during the developmental phase, 80 pregnant mice were randomly divided into one control and three experimental groups (n= 20). The control group received only distilled water, whereas experimental groups were administered 0.7, 1.4, and 2.8 mg/kg/day of methanol extract of C. tinctorius L. from the 6th to 16th day of gestation intraperitoneally (i.p.), respectively. On the 17th day of pregnancy, all of the animals were euthanized and the fetuses were removed and developmental study was performed. C. tinctorius caused decreased fetal body weight, crown rump and tail lengths (p < 0.05) at 1.4 and 2.8 mg/kg/day significantly compare to control group. Skeletal malformations and anomalies included hind limb flexure, exencephally and rhinencephaly were also seen. It was concluded that methanolic extract of C. tinctorius L. has toxic effects during developmental phase on the mice embryo that should be considered when used as a treatment for gynecological disease in pregnant. Key words: Carthamus tinctorius L., Methanolic extract, developmental toxicity, mice, organogenesis.

Evaluation of the teratogenic potential of N-[ N-[3-(3-hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]- l-phenylalanine 1-methyl ester, monohydrate (advantame) in the rat and rabbit

To assess its teratogenic potential, advantame (N-[ N-[3-(3-hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]- l-phenylalanine 1-methyl ester, monohydrate) was administered to mated rats (22/group) in the diet at 0, 5000, 15,000, and 50,000 ppm (providing approximately 465, 1418, and 4828 mg/kg body weight/day), and to mated rabbits (24/group) via oral gavage at 0, 500, 1000, and 2000 mg/kg body weight/day throughout gestation. Shortly before delivery (rats: day 20; rabbits: day 29), animals were killed and subjected to a detailed necropsy. Fetuses were examined for external, visceral, and skeletal alterations. Atypical coloration of the feces and cage liners seen with test diets in both rats and rabbits was attributed to excretion of test material/metabolites in the feces and urine. Advantame had no adverse effect on rat offspring survival or development. The no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity in rats was 50,000 ppm, the highest dietary concentration tested. Due to adverse effects associated with reduced food intake and fecal output, approximately 20% of mated rabbits receiving 2000 mg/kg body weight/day and 1 animal at 1000 mg/kg body weight/day had to be terminated before scheduled necropsy. A NOAEL of 500 mg/kg body weight/day was established for maternal toxicity in rabbits. No teratogenic effects were observed in any animals, and based on a slightly increased incidence of fetal deaths at 2000 mg/kg body weight/day, a finding that was considered to be indirectly related to advantame treatment, 1000 mg/kg body weight/day was considered the NOAEL for developmental toxicity.

Protective effects of pine bark extract on developmental toxicity of cyclophosphamide in rats

This study investigated the protective effects of pine bark extract (Pycnogenol®, PYC) against cyclophosphamide (CP)-induced developmental toxicity in rats. A total of 44 mated females were randomly assigned to the following four experimental groups: (1) vehicle control, (2) CP, (3) CP&PYC, or (4) PYC. All dams were subjected to a Caesarean section on day 20 of gestation, and fetuses were examined for morphological abnormalities. Oxidative stress analysis was performed on maternal hepatic tissues. CP treatment caused decreased fetal and placental weights and increased embryonic resorptions and fetal malformations. In addition, an increased malondialdehyde (MDA) concentration and decreased reduced glutathione (GSH) content and catalase activity were observed in the hepatic tissues. On the contrary, PYC treatment during pregnancy significantly ameliorated the CP-induced embryo–fetal developmental toxicity in rats. Moreover, MDA and GSH concentrations and catalase activity in hepatic tissues were not affected when PYC was administered in conjunction with CP. These results suggest that repeated administration of PYC has beneficial effects against CP-induced embryo–fetal developmental toxicity in rats, and that the protective effects of PYC may be due to both inhibition of lipid peroxidation and increased antioxidant activity.