An inhalation exposure assessment of Hexafluoroisobutylene in pregnant rats

Hexafluoroisobutylene (HFIB) is an important compound widely used in semiconductor lithography materials, refrigerants, fluorine coatings, and pharmaceutical intermediates in the fluorination industry. Owing to its toxicity, the occupational exposure in the workplace, especially for pregnant woman is the concern and there is still lack of the data of HFIB toxicity on pregnancy and fetal development. Here, for the first time, we investigated the effects of HFIB on pregnant rats and fetal development. The pregnant rats were exposed to different doses of HFIB (0 ppm, 27.2 ppm, 53.5 ppm, 105.6 ppm) via whole-body inhalation for the period of organogenesis, which from implantation (gestation day 5) to the day prior to scheduled caesarean section (gestation day 19). The results showed that the pregnant rats exposed to 105.6 ppm HFIB displayed systemic toxicity, including a decrease in body weight and food consumption, as well as tracheal inflammation, pulmonary interstitial inflammation and renal tubular swelling. Moreover, reduced fetal and placental weights, delayed ossification, and a reduced number of ossification centers were observed in fetuses delivered by pregnant rats exposed to 105.6 ppm. These effects were attributed to severe maternal weight loss. In addition, it would be useful to note that no whole-body, visceral or skeletal congenital malformations were observed. However, HFIB exposure at 53.5 ppm showed no significant adverse effects on pregnant rats and fetuses. These findings demonstrate that 105.6 ppm HFIB is a toxic concentration, while 53.5 ppm HFIB is the no-observed-adverse-effect concentration (NOAEC) for both pregnancy and fetal development. This study for the first time to provide evidence for the health risk of HFIB exposure on pregnancy and fetal development.

Grouping of short alkyl-chain branched carboxylic acids for developmental toxicity

Read-across (RAx) and grouping of chemicals into categories are well-known concepts in toxicology. Recently, ECHA proposed a grouping approach for branched-chain carboxylic acids (BCAs) including more than 60 branched-chain saturated carboxylic acids for hazard identification. Grouping was based only on structural considerations. Due to developmental effects of two members, ECHA postulated that "all short carbon chain acids … are likely reproductive and developmental toxicants". This work analyzes available data for BCAs. The number of compounds in the group can be significantly reduced by eliminating metal and organic salts of BCAs, compounds of unknown or variable composition, and complex reaction products or biological materials (UVCB compounds). For the resulting reduced number of compounds, grouping is supported by similar physicochemical data and expected similar biotransformation. However, analysis of adverse effects for compounds in the group and mechanistic information show that BCAs, as a class, do not cause developmental effects in rats. Rather, developmental toxicity is limited to selected BCAs with specific structures that share a common mode of action (histone deacetylase inhibition). Thus, the proposed grouping is unreasonably wide and the more detailed analyses show that structural similarity alone is not sufficient for grouping branched-chain carboxylic acids for developmental toxicity.

Cytotoxicity and maternal toxicity attributed to exposure to Momordica charantia L. (Cucurbitaceae) dry leaf extract

Momordica charantia L. (Cucurbitaceae), popularly known as "bitter melon" or "bitter gourd," is a climbing plant well-adapted to tropical countries. This plant is used traditionally to treat several conditions including diabetes mellitus, inflammation, liver dysfunctions, and cancer. Given the widespread ethnopharmacological use, this study aimed to examine the cytogenetic, maternal, and developmental toxicity attributed to exposure to dry extract of M. charantia leaves using Allium cepa and Wistar rats as test models. First, phytochemical characterization of the dry extract by high performance liquid chromatography (HPLC) analyses was performed. Then, Allium cepa roots were exposed to three different concentrations of the dry extract (0.25, 0.5, or 1 mg/ml) to determine the mitotic index, frequency of chromosomal aberrations, and nuclear abnormalities. In addition, pregnant Wistar rats were administered either 500; 1,000 or 2,000 mg/kg dry extract during the gestational period (GD) days 6-15, and subsequently possible toxic effect on the dams and fetuses were recorded. HPLC analyses confirmed rutin as the main secondary metabolite present in the dry extract. In the Allium cepa test, the dry extract was cytotoxic. In Wistar rats, dry extract administration reduced water and feed intake and mean body mass gain, indicating maternal toxicity during the organogenesis period. However, the dry extract did not markedly affect reproductive outcome parameters evaluated. Regarding developmental toxicity assessment, the dry extract treatment did not significantly alter number of skeletal malformations in the offspring. Data demonstrated that the dry extract of M. charantia leaves presents cytotoxicity and low maternal toxicity, indicating indiscriminate use needs to be avoided.

The exposure in ovo of embryos belonging to Amazonian turtle species Podocnemis expansa (Testudines) to commercial glyphosate and fipronil formulations impairs their growth and changes their skeletal development

Pesticides are widely used in agricultural production; moreover, they can have direct and indirect effect on both flora and fauna. Aquatic organisms, among other animals, including reptiles, are mainly susceptible to contamination effects. Accordingly, the aim of the present study is to test the hypothesis that the incubation of Podocnemis expansa eggs in substrate added with glyphosate and fipronil formulations changes their viability, interferes with their growth and induces bone alterations. Eggs collected in natural environment were artificially incubated in sand moistened with water added with glyphosate Atar 48, at concentrations of 65 or 6500 μg/L (groups G1 and G2, respectively), and with fipronil Regent 800 WG at 4 or 400 μg/L (groups F1 and F2, respectively) or, yet, with the combination of 65 μg/L glyphosate and 4 μg/L fipronil, or with 6500 μg/L glyphosate and 400 μg/L fipronil (groups GF1 and GF2, respectively). The level of exposure to the herein assessed pesticides was quantified at the end of the incubation period; it was done by dosing its concentration in eggshells. Eggs exposed to the tested pesticides did not have their viability affected by it; however, all embryos exposed to the tested pesticides showed lowered body mass at hatch, as well as impaired development. In addition, bone malformation in the scleral ossicular ring was observed in individuals in groups F1, F2 and GF1. Pesticides accumulated in eggshells at concentrations related to exposure level. Thus, the recorded results have evidenced some remarkably relevant, and previously unknown, impacts associated with the exposure of a species listed as lower risk/conservation dependent, which spends most of its life in the water, to two widely used pesticides, at a very sensitive stage of its life, namely: egg incubation on land.

Prenatal developmental toxicity study of herbal tea of Moringa stenopetala and Mentha spicata leaves formulation in Wistar rats

Background

Moringa stenopetala and Mentha spicata have long been used to treat diabetes, hypertension, asthma, and other ailments. Herbal tea of M. stenopetala and Mentha spicata leaves formulation showed better antidiabetic and antihypertensive activities. This study investigated the prenatal developmental toxicity potential of the herbal tea of M. stenopetala and M. spicata leaves blend in rats.

Methods

Wistar pregnant rats were randomly distributed into four groups (n = 8). Group I (control) dams received distilled water. Group II-IV dams were treated with 559.36, 1118.72, and 2237.44 mg/kg of herbal tea of M. stenopetala and Mentha spicata leaves formulations, respectively, during days 5-19 of gestation. Maternal mortality, clinical signs, body weight changes, and food consumption were recorded. On gestation day 20, cesarean sections were performed, and maternal parameters of systemic toxicity (e.g., body weight, serum biochemistry, organ weight, and macro-pathology) as well as reproductive toxicity (e.g., number of corpora lutea, implantations, resorptions (early/late), pre/postimplantation losses, number of fetuses (live/dead), and fetal body weights, length, and their sex ratio) were evaluated. Fetuses were further examined for external, soft tissue, and skeletal alterations.

Results

No herbal tea-related maternal deaths or overt toxic symptoms were observed. The measured maternal systemic and reproductive toxicity parameters showed no herbal tea-associated significant alterations at any dosage levels. Moreover, there were no overt toxic effects of the herbal tea on the fetal external, visceral, or skeletal prenatal growth and development.

Conclusion

The study findings demonstrated that the herbal tea of M. stenopetala and M. spicata leaves blend could be relatively safe/low toxic to pregnant rats and developing fetuses. The no-observed-adverse-effect level (NOAEL) of herbal tea for maternal toxicity, fetotoxicity, and teratogenicity in rats is estimated to be > 2237.44 mg/kg/day.

The codification of hazard and its impact on the hazard versus risk controversy

The long running controversy about the relative merits of hazard-based versus risk-based approaches has been investigated. There are three levels of hazard codification: level 1 divides chemicals into dichotomous bands of hazardous and non-hazardous; level 2 divides chemicals into bands of hazard based on severity and/or potency; and level 3 places each chemical on a continuum of hazard based on severity and/or potency. Any system which imposes compartments onto a continuum will give rise to issues at the boundaries, especially with only two compartments. Level 1 schemes are only justifiable if there is no variation in severity, or potency or if there is no threshold. This is the assumption implicit in GHS/EU classification for carcinogenicity, reproductive toxicity and mutagenicity. However, this assumption has been challenged. Codification level 2 hazard assessments offer a range of choices and reduce the built-in conflict inherent in the level 1 process. Level 3 assessments allow a full range of choices between the extremes and reduce the built-in conflict even more. The underlying reason for the controversy between hazard and risk is the use of level 1 hazard codification schemes in situations where there are ranges of severity and potency which require the use of level 2 or level 3 hazard codification. There is not a major difference between level 2 and level 3 codification, and they can both be used to select appropriate risk management options. Existing level 1 codification schemes should be reviewed and developed into level 2 schemes where appropriate.

Assessing the safety of using the dry extract of Justicia pectoralis Jacq. (Acanthaceae) during pregnancy of Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Justicia pectoralis Jacq. (Acanthaceae), popularly known as tilo, chambá and anador, is widely used in folk medicine in Latin American countries as a sedative, anti-anxiety, reducing menopause symptoms and in the treatment of pathologies of the respiratory tract. Although J. pectoralis is widely used by the female population, there are no studies on the safety of using this species during pregnancy.

AIM OF THIS STUDY

To evaluate the effects of prenatal treatment with dry extract from the aerial parts of J. pectoralis on maternal and developmental toxicity in Wistar rats.

MATERIAL AND METHODS

Pregnant Wistar rats (n = 10/group) were treated from gestational day (GD) 0-20 with the vehicle (control group) or with the dry extract of J. pectoralis at doses of 300, 600 or 1200 mg/kg. During pregnancy, clinical signs of toxicity, maternal weight, feed and water intake were evaluated. On GD 21, rats were anesthetized and intracardiac blood was collected to evaluate biochemical parameters. During cesarean section, reproductive performance parameters were recorded. The liver, kidneys, uterus and ovaries were removed for histopathological analysis. Fetuses were examined for possible malformations and/or skeletal and visceral variations.

RESULTS

Treatment with dry extract of J. pectoralis did not alter weight gain, feed intake or biochemical and maternal reproductive performance parameters There were also no significant histopathological changes in the maternal organs, as well as external, skeletal and visceral malformations in the fetuses.

CONCLUSION

Oral administration of J. pectoralis dry extract during pregnancy did not induce maternal toxicity or embryotoxic and teratogenic effects.

Critical Review of Exposure and Effects: Implications for Setting Regulatory Health Criteria for Ingested Copper

Decades of study indicate that copper oral exposures are typically not a human health concern. Ingesting high levels of soluble copper salts can cause acute gastrointestinal symptoms and, in uncommon cases, liver toxicity in susceptible individuals with repeated exposure. This focused toxicological review evaluated the current literature since the last comprehensive reviews (2007-2010). Our review identified limitations in the existing United States and international guidance for determining an oral reference dose (RfD) for essential metals like copper. Instead, an alternative method using categorical regression analysis to develop an optimal dose that considers deficiency, toxicity, and integrates information from human and animal studies was reviewed for interpreting an oral RfD for copper. We also considered subchronic or chronic toxicity from genetic susceptibility to copper dysregulation leading to rare occurrences of liver and other organ toxicity with elevated copper exposure. Based on this approach, an oral RfD of 0.04 mg Cu/kg/day would be protective of acute or chronic toxicity in adults and children. This RfD is also protective for possible genetic susceptibility to elevated copper exposure and allows for background dietary exposures. This dose is not intended to be protective of patients with rare genetic disorders for copper sensitivity within typical nutritional intake ranges, nor is it protective for those with excessive supplement intake. Less soluble mineral forms of copper in soil have reduced bioavailability as compared with more soluble copper in water and diet, which should be considered in using this RfD for risk assessments of copper.

Importance of gestational hypoglycaemia for foetal malformations and skeletal development in rats

The aim was to investigate embryo-foetal effects of continuous maternal insulin-induced hypoglycaemia extending throughout gestation or until gestation day (GD)17 (typical last day of dosing during pre-clinical evaluation) providing comparator data for safety assessment of longer-acting insulin analogues in non-diabetic rats. Pregnant rats received human insulin (HI)-infusion during gestation until either GD20 or GD17 (HI-GD20; HI-GD17). On GD20, foetal abnormalities and skeletal ossification/mineralisation were evaluated. HI-infusion induced continuous hypoglycaemia. Foetal skeletal and eye malformations (e.g. bent ribs, microphthalmia) were common in both groups. Foetal size and skeletal ossification/mineralisation decreased, particularly with infusion throughout gestation. Concluding, insulin-induced hypoglycaemia during gestation in non-diabetic rats is damaging to embryo-foetal growth and skeletal development, particularly after GD17. Three days without HI-infusion after GD17 allows for some developmental catch-up. Eye development is sensitive to HI-infusion before GD17. These results should serve as a benchmark during pre-clinical safety assessment of longer-acting insulin analogues tested in rats.

Prenatal toxicity and maternal-fetal distribution of 1,3,5,8-tetrachloronaphthalene (1,3,5,8-TeCN) in Wistar rats

1,3,5,8-tetrachloronaphthalene (1,3,5,8-TeCN) is a Persistent Organic Pollutant (POP) that belongs to the group of polychlorinated naphthalenes (PCNs). The aim of the study was to investigate the maternal-fetal distribution and prenatal toxicity of 1,3,5,8-TeCN after its administration to pregnant Wistar rats during organogenesis. Radiolabeled 1,3,5,8-tetrachloronaphthalene-[ring-U-³H] was given by gavage at a dose of 0.3 mg per dam to evaluate its tissue distribution, and that of unlabeled 1,3,5,8-TeCN, at daily doses of 0.3, 1.0 or 3.0 mg kg b.w.^-1 to assess prenatal toxicity. After a single administration of 1,3,5,8-TeCN, the highest concentration was detected in maternal adipose tissue. The concentration in the brain, uterus, kidneys, adrenals, ovaries, lungs and liver established in dams were two to nine times higher than in the maternal blood. 1,3,5,8-TeCN penetrated the blood-brain-barrier and the placenta. The results obtained from developmental toxicity indicate that 1,3,5,8-TeCN did not cause maternal toxicity and was not embryotoxic or teratogenic. However, fetotoxic effects were observed after non-toxic doses for dams (1.0 and 3.0 mg∙b.w.^-1·day^-1). 1,3,5,8-TeCN did not induce congenital skeletal defects but increased the number of fetuses with sternum ossification delay. After a dose of 3.0 mg kg b.w.^-1·day^-1, significantly more fetuses were found with enlargement of the renal pelvis: unilateral in female offspring and bilateral in male offspring. At the doses used, 1,3,5,8-TeCN, unlike hexachloronaphthalene, was not a CYP1A1 inducer.

Prenatal developmental toxicity evaluation of Verbena officinalis during gestation period in female Sprague-Dawley rats

Verbena officinalis is widely used by women for maintaining general health and treating various gynaecological disorders during pregnancy. A case report has indicated that the consumption of V. officinalis induced an abortifacient effect. Hence, this study aimed to investigate the prenatal developmental toxicity of this plant according to OECD guideline (no. 414). A total of 50 pregnant female rats (dams) were distributed into five groups (n = 10); 500 mg/kg 1000 mg/2000 mg/kg and 3000 mg/kg of V. offcinalis extracts and the fifth group served as a normal control. All dams received their respective oral single daily treatment from the 6th to the 20th day of gestation. Maternal clinical toxicity signs, body weight and weight gain were recorded. Caesarean sections were performed on day 21 to evaluate embryo-foetal developmental toxicity. For dams, ovaries were harvested and weighed. The number of corpora lutea, implantation sites, and resorptions were recorded. No mortality was observed in dams, but their body weight gain was significantly reduced particularly in dams treated with 2000 and 3000 mg/kg V. officinalis. Asymmetrical distribution of implantation sites and embryos were observed. Embryo-fetotoxicity retardation was observed as evident by the decrease in foetal weight, head cranium, tail length, and higher incidence in the pre-and post-implantation loss. Some foetal skeleton abnormalities such as incomplete ossification of skull, sternebrae, and metatarsal bones were observed in foetuses of the 2000 and 3000 mg/kg V. officinalis-treated dams. LC/MS analysis identified the major constituents including geniposidic acid, tuberonic acid glucoside, luteolin 7, 3'-digalacturonide, iridotrial and apigenin. The glycosylated flavonoids such as apigenin and luteolin could be responsible for the reported prenatal developmental toxicity. In conclusion, the use of V. officinalis during pregnancy is not safe indicating evidence-based toxic effects on the reproductive performance of dams and dose-dependent risk potentials to the foetuses.

Impact of chloroform exposures on reproductive and developmental outcomes: A systematic review of the scientific literature

AIMS

We assessed the animal and epidemiological data to determine if chloroform exposure causes developmental and/or reproductive toxicity.

RESULTS AND DISCUSSION

Initial scoping identified developmental toxicity as the primary area of concern. At levels producing maternal toxicity in rats and mice, chloroform caused decrements in fetal weights and associated delays in ossification. In a single mouse inhalation study, exposure to a high concentration of chloroform was associated with small fetuses and increased cleft palate. However, oral exposure of mice to chloroform at a dose 4 times higher was negative for cleft palate; multiple inhalation studies in rats were also negative. Epidemiologic data on low birth weight and small for gestational age were generally equivocal, preventing conclusions from being drawn for humans. The animal data also show evidence of very early (peri-implantation) total litter losses at very high exposure levels. This effect is likely maternally mediated rather than a direct effect on the offspring. Finally, the epidemiologic data indicate a possible association of higher chloroform exposure with lower risk of preterm birth (<37 weeks gestation).

CONCLUSIONS

The available animal data suggest that exposures lower than those causing maternal toxicity should be without developmental effects in the offspring. Also, most studies in humans rely on group-level geographic exposure data, providing only weak epidemiologic evidence for an association with development outcomes and fail to establish a causal role for chloroform in the induction of adverse developmental outcomes at environmentally relevant concentrations.

Bone development in laboratory mammals used in developmental toxicity studies

Evaluation of the skeleton in laboratory animals is a standard component of developmental toxicology testing. Standard methods of performing the evaluation have been established, and modification of the evaluation using imaging technologies is under development. The embryology of the rodent, rabbit, and primate skeleton has been characterized in detail and summarized herein. The rich literature on variations and malformations in skeletal development that can occur in the offspring of normal animals and animals exposed to test articles in toxicology studies is reviewed. These perturbations of skeletal development include ossification delays, alterations in number, shape, and size of ossification centers, and alterations in numbers of ribs and vertebrae. Because the skeleton is undergoing developmental changes at the time fetuses are evaluated in most study designs, transient delays in development can produce apparent findings of abnormal skeletal structure. The determination of whether a finding represents a permanent change in embryo development with adverse consequences for the organism is important in study interpretation. Knowledge of embryological processes and schedules can assist in interpretation of skeletal findings.

Safety of d-ribose as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on D-ribose as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The applicant intends to market the NF as ingredient in a variety of foods, food supplements and in certain foods for specific groups. The NF is produced by fermentation using a transketolase-deficient strain of Bacillus subtilis and marketed as Bioenergy Ribose™. The information provided on the batch-to-batch variability, specifications, stability, production process and history of the organism used as a source of the NF is sufficient and does not raise safety concerns. The Panel considers that the effects observed in a subchronic toxicity study in rats could be the consequence of nutritional imbalances, but toxicological effects could not be ruled out; from this study, the Panel derived a No observed adverse effect level (NOAEL) of 3.6 g/kg body weight (bw) per day. From the human studies indicating a potential decrease in glucose levels and/or the occurrence of transient symptomatic hypoglycaemia at intakes of 10 g of d-ribose, the Panel defined 70 mg/kg bw per day as the NOAEL with respect to hypoglycaemia that can be considered applicable for adults. For children, the Panel acknowledges the lack of human data directly relevant for this population group. Based on the NOAEL derived from the subchronic toxicity study in rats, an acceptable level of intake of 36 mg/kg bw per day was defined that would also take into account the potentially increased sensitivity of certain population groups to hypoglycaemia. The Panel concludes that the NF is safe for the general population at intake levels up to 36 mg/kg bw per day and considers that the safety of the NF at the intended uses and use levels as proposed by the applicant has not been established.

Comparative developmental toxicity evaluation of di- n-hexyl phthalate and dicyclohexyl phthalate in rats

To investigate the effects of di- n-hexyl phthalate (DHP) and dicyclohexyl phthalate (DCHP) on the development of fetus and placenta in utero, pregnant rats were exposed to DHP or DCHP at dosages of 0, 20, 100, and 500 mg/kg bw/day, by gavage, on gestational days 6-19. Anogenital distance (AGD) and AGD-body weight^1/3 ratio of female fetuses decreased in all treatment groups in a non-dose-response way. The ossification centers of bones and the intensity of Alizarin red stain of the fetuses decreased in all treatment groups. The white blood cell levels of fetuses in DHP and DCHP exposed groups increased at all dosages. Mean cell hemoglobin, hemoglobin concentrations, and hemoglobin levels of all DHP and DCHP treated male and female fetuses were reduced. Histopathologic changes (hemorrhage in labyrinth, degeneration of spongiotrophoblast, hemorrhage, decreased and irregular vessel formation, and edema in the basal zone) were observed in placentas at high dosages of DHP and DCHP. In contrast, there was no change in weight gain of dams in DHP and DCHP exposed groups compared to control, but resorption rate, reduced fetal weight, delayed ossification, placental disruption, and hematologic parameters clearly indicated that in utero DHP and DCHP exposure resulted in intrauterine growth retardation in rats.

A toxicological review of the ethylene glycol series: Commonalities and differences in toxicity and modes of action

This review summarizes the hazards, exposure and risk that are associated with ethylene glycols (EGs) in their intended applications. Ethylene glycol (EG; CAS RN 107-21-1) and its related oligomers include mono-, di-, tri-, tetra-, and penta-EG. All of the EGs are quickly and extensively absorbed following ingestion and inhalation, but not by the dermal route. Metabolism involves oxidation to the mono- and dicarboxylic acids. Elimination is primarily through the urine as the parent compound or the monoacid, and, in the case of EG, also as exhaled carbon dioxide. All EGs exert acute toxicity in a similar manner, characterized by CNS depression and metabolic acidosis in humans and rodents; the larger molecules being proportionally less acutely toxic on a strict mg/kg basis. Species differences exist in the metabolism and distribution of toxic metabolites, particularly with the formation of glycolic acids and oxalates (OX) from EG and diethylene glycol (DEG); OX are not formed to a significant degree in higher ethylene glycols. Among rodents, rats are more sensitive than mice, and males more sensitive than females to the acute and repeated-dose toxicity of EG. The metabolic formation of glycolic acid (GA), diglycolic acid (DGA), and OX are associated with nephrotoxicity in humans and rodents following single and repeated exposures. However, physiological and metabolic differences in the rate of formation of GA, DGA and OX and their distribution result in EG and DEG causing embryotoxicity in rats, but not rabbits. This rodent-specific sensitivity indicates that EG and its higher oligomers are not anticipated to be embryotoxic in humans at environmentally relevant doses. None of the compounds present developmental toxicity concerns at doses that do not also cause significant maternal toxicity, nor do any of the EGs cause adverse effects on fertility. The EGs are neither genotoxic nor carcinogenic. A read-across matrix is presented, which considers the common and distinct toxicological properties of each compound. It is concluded that EGs pose no risk to human health as a result of their intended use patterns.

Postnatal fate of prenatal-induced fetal alterations in laboratory animals

Currently it is common practice to evaluate the developmental toxicity hazard of chemicals or pharmaceuticals by evaluation of fetuses after administration of the compound to pregnant animals. These studies are designed to provide possible compound-related fetal changes near term, which are usually classified into malformations or variations. Malformations, but not variations are expected to adversely affect the survival or health. Therefore, classification has striking different regulatory consequences. For categorization as variation reversibility is an important criterion, but it is usually not examined in a standard guideline study. Although this issue has already been recognized long time ago, data dealing with the postnatal reversibility of fetal alterations are still rare. In the current review, literature data, regulatory documents as well as in-house data were compiled. Beside skeletal alterations of skull, vertebral column, ribs, shoulder and pelvic girdle, and extremities, kidney and heart defects are discussed and assessed.

Mechanism of Developmental Effects in Rats Caused by an N-Phenylimide Herbicide: Transient Fetal Anemia and Sequelae during Mid-to-Late Gestation

BACKGROUND

Rat developmental toxicity including embryolethality and teratogenicity (mainly ventricular septal defects [VSDs] and wavy ribs) was produced by an N-phenylimide herbicide that inhibits protoporphyrinogen oxidase (PPO) common to chlorophyll and heme biosynthesis. Major characteristics of the developmental toxicity included species difference between rats and rabbits, compound-specific difference among structurally similar herbicides, and sensitive period. Protoporphyrin accumulation in treated fetuses closely correlated with the major characteristics. Iron deposits in erythroblastic mitochondria and degeneration of erythroblasts were observed in treated rat fetuses. In this study we investigated fetal anemia and subsequent developmental effects in rats, and inhibition of PPO in rats, rabbits, and humans by the herbicides in vitro.

METHODS

Fetuses were treated on gestational day (GD) 12 and removed on GDs 13 through 20. All litters were examined externally. One half of litters were examined for blood and skeletal development, and the other half for interventricular foramen closure. Effects on PPO were determined in mitochondria from embryos and adult livers.

RESULTS

Fetal anemia in rats was evident on GDs 13 through 16. Subsequently, enlarged heart, delayed closure of the foramen, reduced serum protein, and retarded rib ossification were observed. In vitro PPO inhibition exhibited species- and compound-specific differences corresponding to the developmental toxicity.

CONCLUSION

We propose that developmental toxicity results from PPO inhibition in primitive erythroblasts, causing transient fetal anemia followed by death. Compensatory enlargement of the fetal heart results in failure of interventricular foramen closure and VSD. Reduced serum protein leads to delayed ossification and wavy ribs.

Delayed-Release Dimethyl Fumarate and Pregnancy: Preclinical Studies and Pregnancy Outcomes from Clinical Trials and Postmarketing Experience

Introduction

Delayed-release dimethyl fumarate (DMF; also known as gastro-resistant DMF) is an oral agent for the treatment of relapsing forms of multiple sclerosis (MS). No formal studies of DMF were conducted in pregnant women, although pregnancies have occurred during clinical trials and in the postmarketing setting.

Methods

Preclinical developmental and reproductive toxicology studies were performed with DMF in rats and rabbits. As of March 26, 2014, the DMF clinical development program included a total of 4132 subjects consisting of 2898 patients with MS, 320 psoriasis patients, 101 rheumatoid arthritis patients, and 813 healthy volunteers. Subjects were required to use reliable contraception and immediately discontinue treatment in the event of pregnancy.

Results

Animal studies showed no evidence of impaired fertility or teratogenicity with DMF. Overall as of June 30, 2014, 63 pregnancies were reported in clinical trials. Outcomes are known for 39 of 42 subjects receiving DMF and include 26 live births (67%), three spontaneous abortions (8%), and 10 elective terminations (26%); follow-up is ongoing in 2 cases and one patient was lost to follow-up. The incidence of spontaneous abortion in subjects exposed to DMF was consistent with the expected rate of early pregnancy loss in the general population (12–22%). A total of 135 pregnancies were reported in the postmarketing setting (spontaneous and solicited reports). Outcomes are known for 30 cases and include 10 live births, 13 spontaneous abortions, and 5 elective terminations; follow-up is ongoing in 103 cases and 2 patients have been lost to follow-up.

Conclusion

Although data are limited and all known exposures have occurred in the first trimester, no increased risk of fetal abnormalities or adverse pregnancy outcomes associated with gestational exposure to DMF has been observed.

Funding

Biogen, Inc.

Electronic supplementary material

The online version of this article (doi:10.1007/s40120-015-0033-1) contains supplementary material, which is available to authorized users.

Developmental toxicity of hexachloronaphthalene in Wistar rats. A role of CYP1A1 expression

Hexachloronaphthalene (HxCN) is one of the most toxic congeners of polychlorinated naphthalenes (PCNs). This study assesses the prenatal toxicity of HxCN after daily administration at doses of 0.1-1.0mg/kg b.w. to pregnant Wistar rats during organogenesis. We evaluated also the expression of CYP1A1 mRNA and protein in the livers of dams and fetuses, as well as the placenta. The results indicate that 0.3mg/kg b.w. was the lowest HxCN toxic dose for dams (LOAEL) while a dose of 0.1mg/kg b.w. was sufficient to impair the intrauterine development of embryos/fetuses without maternal toxicity. Regardless of the applied dose, HxCN generated embryotoxic effects. Dose-dependent fetotoxic effects were associated with HxCN exposure. HxCN was found to be a strong inducer of maternal and fetal CYP1A1. Expression of CYP1A1 mRNA in the placenta appears to be the most sensitive marker of HxCN exposure.

Relationship between bent long bones, bent scapulae, and wavy ribs: malformations or variations?

BACKGROUND

Shortened and bent long bones and bent scapulae are sometimes reported in fetuses with wavy ribs (Carney and Kimmel, ). Wavy ribs are typically seen in the presence of maternal and developmental toxicity, are transient and reversible postnatally, and are considered to be variations rather than malformations.

METHODS

We further assessed the literature cited in Kimmel and Carney () as well as papers published since then to determine under what conditions bent long bones in the absence of gross limb defects and bent scapulae were reported and whether information was available on the transient or permanent nature of these effects.

RESULTS

Long bone and/or scapular changes almost always occurred at a lower incidence than wavy ribs. In every case, maternal and fetal toxicity occurred at the same dose levels. In a few studies, pups were followed sequentially after birth and bent long bones and scapulae were transient in nature and appeared normal by the time of weaning. Rabbits were much less likely to show wavy ribs or long bone and scapular changes at birth, even in the presence of severe maternal and fetal toxicity. This species difference may be due in part to the great increase in bone mass and remodeling that occurs during the first few postnatal weeks in rodents, but which takes place during the longer fetal period in rabbits.

CONCLUSION

Our conclusion from this review is that bent long bones and scapulae, like wavy ribs, appear to be secondary to maternal and developmental toxicity, are transient, and like wavy ribs should be considered variations rather than malformations.

Guidance on classification for reproductive toxicity under the globally harmonized system of classification and labelling of chemicals (GHS)

The Globally Harmonised System of Classification (GHS) is a framework within which the intrinsic hazards of substances may be determined and communicated. It is not a legislative instrument per se, but is enacted into national legislation with the appropriate legislative instruments. GHS covers many aspects of effects upon health and the environment, including adverse effects upon sexual function and fertility or on development. Classification for these effects is based upon observations in humans or from properly designed experiments in animals, although only the latter is covered herein. The decision to classify a substance based upon experimental data, and the category of classification ascribed, is determined by the level of evidence that is available for an adverse effect on sexual function and fertility or on development that does not arise as a secondary non-specific consequence of other toxic effect. This document offers guidance on the determination of level of concern as a measure of adversity, and the level of evidence to ascribe classification based on data from tests in laboratory animals.

Developmental toxicity studies with atrazine and its major metabolites in rats and rabbits

Atrazine (ATR), hydroxyatrazine (OH-ATR), and the three chloro metabolites of ATR (deethylatrazine [DEA], deisopropylatrazine [DIA], diaminochlorotriazine [DACT]) were evaluated for developmental effects in rats and rabbits. Three developmental toxicity studies were conducted on ATR in rats (two studies) and rabbits and a developmental toxicity study was conducted in rats for each of the four ATR metabolites DEA, DIA, DACT, and OH-ATZ. ATR administration by gavage to pregnant rats and rabbits from implantation (gestation day [GD] 6 in rat, GD 7 in rabbit) through closure of the palate (GD 15 in rat and GD 19 in rabbit) did not statistically significantly alter the incidence of developmental abnormalities or malformations at dose levels up to 100 (rat) or 75 (rabbit) mg/kg bw/day. There were no effects on developmental toxicity parameters for DEA, DIA, DACT, or OH-ATR at oral dose levels up to 100, 100, 150, or 125 mg/kg bw/day, respectively, with the exception of reductions in fetal body weight by DACT and OH-ATR in the presence of decreased maternal body weight gain. ATR did not adversely affect developmental end points in a two-generation study conducted in rats exposed to dose levels up to 500 ppm (38.7 mg/kg/day) in the diet. The 500-ppm dose level resulted in significantly reduced maternal body weight gain. Overall, data show that neither ATR nor its metabolites statistically significantly affected rat or rabbit embryo-fetal development even at dose levels producing maternal toxicity.

Fertility and developmental toxicity assessment in rats and rabbits with LY500307, a selective estrogen receptor beta (ERβ) agonist

LY500307 is a selective estrogen receptor beta (ERβ) agonist that was developed for the treatment of benign prostatic hyperplasia. The in vitro functional selectivity of LY500307 for ERβ agonist activity is 32-fold above the activity at the alpha receptor (ERα). LY500307 was evaluated in a series of male (M) and female (F) rat fertility and rat and rabbit embryo-fetal development (EFD) studies, using 20 or 25 animals/group. LY500307 was administered daily by oral gavage starting 2 weeks (F) or 10 weeks (M) before mating, during cohabitation, until necropsy (M) or through gestation day (GD) 6 (F) in the fertility studies and from GD 6 to 17 (rats) or GD 7 to 19 (rabbits) in the EFD studies. Dosage levels of LY500307 ranged from 0.03 to 10 mg/kg/day for rats and from 1 to 25 mg/kg/day for rabbits. Fertility, estrous, maternal reproductive endpoints, conceptus viability, sperm parameters, organ weights, and histopathology were evaluated in the fertility studies. Maternal reproductive endpoints and fetal viability, weight, and morphology were evaluated in the EFD studies. Toxicokinetics were assessed in satellite animals. At 10 mg/kg/day in the male fertility study, findings included decreased body weight (BW); food consumption (FC); fertility, mating, and conception indices; sperm concentration; and reproductive tissue weight (associated with atrophic histologic changes). In the female fertility study, effects included decreased BW and FC at ≥0.3 mg/kg/day and persistent diestrus, delayed mating, and reduced fertility/conception indices at 3 mg/kg/day. In the rat EFD study, findings included decreased maternal BW and FC and increased incidences of adverse clinical signs, abortion, maternal mortality/moribundity, postimplantation loss, and fetal skeletal variations at 3 mg/kg/day. Effects in the rabbit EFD study were limited to decreases in maternal BW and FC at 25 mg/kg/day. In general, systemic maternal exposure increased proportionally with dosage in rats, but less than proportionally in rabbits. In conclusion, the no-observed adverse effect levels following LY500307 administration were 1 mg/kg/day for male rat fertility, 0.3 mg/kg/day for female rat fertility and EFD, and 25 mg/kg/day for rabbit EFD. Adverse reproductive and developmental effects only occurred at or above parentally toxic dosage levels and were considered predominantly due to off-target ERα effects.

Assaying embryotoxicity in the test tube: current limitations of the embryonic stem cell test (EST) challenging its applicability domain

Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.

The prenatal toxic effect of methylmercury on the development of the appendicular skeleton of rat fetuses and the protective role of vitamin E

Methylmercury (MeHg) is an environmental contaminant that is found in many ecosystems. Many studies reported that MeHg toxicity is accompanied by increased lipid peroxidation that may lead to oxidative damage to DNA, RNA, and proteins. Vitamin E is considered as the most effective antioxidant preventing lipid peroxidation. The aim of this study was to evaluate the effects of MeHg exposure during pregnancy on the development of the appendicular skeleton in rat fetuses and whether vitamin E administration could reduce this toxicity. Positively mated adult female Sprague-Dawley rats were used and divided into the following experimental groups: control group, received only deionized water, and four MeHg treated groups received 1 mg of MeHg/kg/d, 2 mg of MeHg/kg/d, 1 mg of MeHg/kg/d plus 150 mg of vitamin E/kg/d, and 2 mg of MeHg/kg/d, plus 150 mg of vitamin E/kg/d starting from Day 0 of gestation. On Day 20 of gestation, the fetuses from the pregnant rats were extracted and the fetal growth parameters were evaluated. Skeletal evaluation of ossification of both fore- and hind-limbs, and coxal bones were undertaken. Results showed that treatment with MeHg caused adverse effects on fetal growth parameters and ossification of the bones. The coadministration of vitamin E with MeHg revealed an improvement in these parameters. These results suggest that vitamin E may ameliorate some aspects of MeHg developmental toxicity. The underlying and human health implications warrant further investigations.

Assessment of immunization against recombinant human bone morphogenetic protein-2 (dibotermin alpha) on reproduction and development in rabbits

BACKGROUND

To determine if the fetus was affected by maternal antibodies to BMP-2, the antibody response and developmental effects in fetuses from does immunized against recombinant human BMP-2 were evaluated.

METHODS

Female New Zealand White rabbits received four intramuscular injections (on premating days 1, 8, 22, and 43 [3 days before mating]) of saline and adjuvant (TiterMax(®) Gold [control]) or recombinant human BMP-2 (2 mg/dose) and adjuvant (treated). On GD 29, fetuses were examined, and maternal and fetal anti-BMP-2 titer levels and neutralizing activity were assessed.

RESULTS

Anti-BMP-2 antibodies were detected in 17 of 18 treated does (127 of 151 fetuses), and low levels were detected in 2 of 16 control does (no fetal exposure observed). In general, levels of fetal anti-BMP-2 antibodies were similar to those in the does, and pregnancy did not boost the immune response to BMP-2. There were no effects of immunization or anti-BMP-2 antibody titer levels on embryo-fetal viability, fetal weight, or fetal external, visceral, or skeletal development. Only a small number of fetuses (n = 4) displayed detectable neutralizing anti-BMP-2 antibodies, but there were no treatment-related effects in those fetuses.

CONCLUSIONS

The lack of embryo-fetal effects may be due to dosage effects of neutralizing anti-BMP-2 antibodies, timing of exposure (stage and duration) to neutralizing anti-BMP-2 antibodies, and/or redundancy of effects of the various BMPs.

Differences in spontaneous fetal abnormalities among three outbred stocks of Wistar Hannover rats in Japan

Wistar Hannover rats, which are maintained by three animal breeders in Japan, were examined to obtain basic data on reproductive and developmental parameters. Untreated pregnant females were terminated on gestational day 20, and the fetuses were removed by cesarian section. The fetuses were counted, weighed and examined for morphological abnormalities. There were few differences among the three stocks of Wistar Hannover rats on the numbers of implantations and live fetuses, sex ratio and fetal weights. The most common fetal abnormalities were the presence of left-sided umbilical arteries, supernumerary ribs and wavy ribs. The incidences of these abnormalities were different among the three stocks of Wistar Hannover rats. Our results provide important data which should be considered in the determination of which stock of rat is used in developmental studies.