Two-generation Reproductive Study Research Articles

Two generation reproduction toxicity study of GmDREB3 gene modified wheat in Wistar rats

To study reproductive toxicity of gene modified wheat generated by introducing DREB3 (drought response element binding protein 3) gene, Wistar rats of were allocated into 3 groups and fed with DREB3 gene modified wheat mixture diet (GM group), non-gene modified wheat mixture diet (Non-GM group) and AIN-93 diet (Control group) from parental generation (F0) to the second offspring (F2). GM wheat and Non-GM wheat, Jimai22, were both formulated into diets at a ratio of 69.55% according to AIN93 diet for rodent animals. Compared with non-GM group, no biologically related differences were observed in GM group rats with respect to reproductive performance such as fertility rate, gestation rate, mean duration, hormone level, reproductive organ pathology and developmental parameters such as body weight, body length, food consumption, neuropathy, behavior, immunotoxicity, hematology and serum chemistry. In conclusion, no adverse effect were found relevant to GM wheat in the two generation reproduction toxicity study, indicating the GM wheat is a safe alternative for its counterpart wheat regarding to reproduction toxicity.

Two-generation reproduction and limited teratology studies of ethanamizuril fed to rats.

Ethanamizuril, a new anticoccidial agent that belongs to triazine derivatives, has a broad and good anticoccidial activity. To evaluate the reproductive toxicity and teratogenic potential of ethanamizuril, different concentrations of ethanamizuril were administered to Sprague-Dawley rats by feeding diets containing 0, 2, 8, and 30 ppm, respectively. Each group consisting of 30 males and 30 females (F0) was treated with different concentrations of ethanamizuril through a 13-week period before mating and during mating, gestation, parturition and lactation. In the 30 ppm dose group, pup body weight on days 7 and 21 in F1 offspring and day 21 in the F2a offspring were significantly decreased. A limited teratogenicity study was performed in combination with the F1 generation of a two-generation reproduction study. F1 offspring of the reproduction study were mated after weaning of the F2a offspring. Pregnant female rats were subjected to cesarean section on gestational day 20 for teratogenic examination. No obvious body weights, fetal body lengths, tail lengths, litter weights, number of viable fetuses, external, skeletal, or visceral malformations in fetuses were noted in any groups in the teratogenic test, but ethanamizuril could be passed on to offspring through lactation.

Cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-Z) (2018).

Cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-Z) is a clear, colorless liquid that finds uses as a foam-blowing agent, refrigerant, fire extinguishing agent, and solvent. HFO-1336mzz-Z is not an acute dermal or eye irritant and has very low acute toxicity via inhalation exposure (4-h lethal concentration (LC50) > 102,000 ppm). The no-observed adverse effect level (NOAEL) and lowest-observed adverse effect level (LOAEL) for cardiac sensitization (in epinephrine-challenged dogs) were 12,500 ppm and 25,000 ppm, respectively. In a GLP, subacute (4-week) repeat-dose inhalation study in Crl: CD(SD) male and female rats at exposure concentrations of 0, 2500, 5000, or 10,000 ppm, the only significant observations attributed to exposure were reduced body weight, reduced body weight gain, and reduced food consumption. The study NOAEL was determined to be 2500 ppm. Two separate GLP, 13-week repeat-dose inhalation studies (Organisation for Economic Cooperation and Development (OECD) 413) have been conducted on HFO-1336mzz-Z using male and female Crl: CD (SD) rats. In the first study, exposure concentrations were 0, 500, 1500, or 10,000 ppm, and in the second study, 0, 3000, 4000, 5000, or 7500 ppm. The only significant exposure-related observations in the first study were reductions in body weights, food consumption, and food efficiency in males and females at 10,000 ppm (study NOAEL = 1500 ppm). In the second study, done in part to better define the NOAEL, reductions in body weight and food consumption were observed in males at 7500 ppm; there were no exposure-related observations on these end points in females. Therefore, the study NOAEL was established at 5000 ppm for males and 7500 ppm for females. HFO-1336mzz-Z has also been examined for its potential to produce developmental toxicity in both Crl: CD(SD) rats (0, 500, 1500, or 10,000 ppm) and New Zealand White rabbits (0, 2500, 5000, 7500, or 15,000 ppm) according to GLP and OECD 414. The NOAEL for both maternal and fetal effects in rats was 1500 ppm and the NOAELs for maternal effects and fetal effects in rabbits were 5000 ppm and 7500 ppm, respectively. A non-GLP, two-generation reproductive pilot study, for a planned multigenerational study noted reduced body weight and body weight gain in males at 1500 ppm and above; the NOAEL for this pilot study was set at 500 ppm. There are no chronic toxicity/carcinogenicity studies available, and HFO-1336mzz-Z was not genotoxic/mutagenic in in vitro and in vivo studies. The NOAEL for male rats of 5000 ppm (based on reductions in body weight and food consumption) from the 13-week inhalation study was selected as the point of departure for the derivation of the 8-h time-weighted average (TWA), health-based workplace environmental exposure level (WEEL) value. This subchronic inhalation NOAEL was adjusted to account for duration of exposure, inter-individual variability, and intra-individual variability. The resulting 8-h TWA WEEL value of 500 ppm is fully expected to provide a significant margin of safety against the production of any potential adverse health effects in workers following long-term inhalation exposure to HFO-1336mzz-Z vapor.

Investigation on Toxicity and Teratogenicity in Rats of a Retinoid-Polyamine Conjugate with Potent Anti-Inflammatory Properties.

Previous studies have shown that N(1),N(12)-bis(all-trans-retinoyl)spermine (RASP), a retinoid analog, inhibits RNase P activity and angiogenesis in the chicken embryo chorioallantoic membrane, demonstrates anti-tumor activity on prostate cancer cells, and acts as anti-inflammatory agent, being more effective and less toxic than all-trans retinoic acid. In an attempt to further characterize the biological profile of RASP, we tested its effects on organ toxicity and teratogenicity by daily oral gavage of RASP at a level of 50 mg/Kg of body weight in two generations of rats. We found that this compound does not induce changes to the body growth, the appearance of physical features, and the animal's reflexes. Additionally, no substantial histopathological lesions were found in brain, heart, lung, thymus, liver, thyroid gland, adrenal gland, pituitary gland, kidneys, spleen, skin, femora, prostate, testis, epididymis, vagina, uterus, and ovaries of RASP-treated animals. These results suggest RASP, as a promising lead compound for the treatment of several dermatological disorders and certain cancer types, has apparently minimal toxic side-effects as revealed in this two-generation reproduction study in rats.

Two-generation reproduction and teratology studies of feeding aditoprim in Wistar rats.

Aditoprim, a new bacteriostatic agent that belongs to diaminopyrimidines, has a broad antimicrobial spectrum, good antibacterial activity and excellent pharmacokinetics. To evaluate the reproductive toxicity and teratogenic potential of aditoprim, different concentrations of aditoprim were administered to Wistar rats by feeding diets containing 0, 20, 100 and 1000 mg kg(-1) , respectively. Each group consisting of 18 males and 25 females (F0 ) was treated with different concentrations of aditoprim through a 13-week period before mating and during mating, gestation, parturition and lactation. At weaning, 20 males and 25 females of the F1 generation weanlings per group were selected randomly as parents for the F2 generation. Selected F1 weanlings were exposed to the same diet and treatment as their parents. At 1000 mg kg(-1) dose group, body weights in F0 and F1 rats, fetal body weight on day 21 (0, 4 and 21) after birth and number of viable fetuses in the F0 and F1 generation significantly decreased. Teratogenicity study was performed in combination with the F1 generation of a two-generation reproduction study. F1 parents of the reproduction study were mated after weaning of the F2a pups. Pregnant female rats were subjected to cesarean section on gestational day 20 for teratogenic examination. At 1000 mg kg(-1) group, body weights, fetal body lengths, tail lengths, litter weights and number of viable fetuses were significantly decreased. No obvious external, skeletal or visceral malformations in fetuses were noted in any groups in the teratogenic test. The no-observed-adverse-effect level for reproduction/development toxicity of aditoprim was 100 mg kg(-1) diet (about 7.89-9.25 mg kg(-1) body weight day(-1) ).

Flumioxazin

The Food Safety Commission of Japan (FSCJ) conducted a risk assessment of flumioxazin (CAS No. 103361–09-7), an N-phenylphthalimide herbicide, based on summary reports submitted by the applicants and documents from the governments of the US and Australia. Major adverse effects of flumioxazin observed are on blood (anemia), and liver (hepatocellular hypertrophy and increased organ weight). None of neurotoxicity, immunotoxicity and carcinogenicity, as well as genotoxicity relevant to human health were observed. In a two-generation reproduction study of flumioxazin in rats, decreased copulation index and birth rate, and decreased viability index on day 4 of the offsprings were observed. In developmental toxicity tests in rats, cardiovascular malformations including ventricular septal defect, and skeletal malformations such as curvature of the scapula were identified in fetuses. Based on the results from various studies, FSCJ specified the residue definition for dietary risk assessment in agricultural and livestock products to be flumioxazin (parent compound only). The lowest no-observed-adverse-effect level (NOAEL) obtained in all studies was 1.8 mg/kg bw/day in a combined two-year chronic toxicity/carcinogenicity study in rats. FSCJ specified an acceptable daily intake (ADI) of 0.018 mg/kg bw/day by applying a safety factor of 100 to the NOAEL.

A two-generation reproduction study with transgenic Bt rice TT51 in Wistar rats

TT51 is a transgenic Bt rice created by fusion a synthetic CryAb/CryAc gene into rice MingHui63. A significant number of animal feeding studies with transgenic crops have been carried out with the rapid development of transgenic crops. However, the evidence is far from identifying whether certain novel transgenic crops possess potential danger for human or animal health after long-term consumption. Rice-based diets, containing 60% ordinary grocery rice, MingHui63 rice or TT51 rice by weight, were fed to two generations of male and female rats in order to determine the potential reproductive effects of TT51. In this study, both clinical performance variables and histopathological responses were examined and compared between groups. There were no significant differences between groups on body weights, food consumption, reproductive data and relative organ/body weights. There were some statistically significant differences in hematology and serum chemistry parameters, but no histological abnormalities were seen in the brain, heart, liver, spleen, kidneys, stomach, small intestine, thymus, ovaries, uterus, testes and epididymides. Based on the results, under the circumstance of this study TT51 show no significant differences on reproduction performance of rats compared with MingHui63 and the control.

P12—Male reproductive system parameters in a two-generation reproduction study of ammonium perfluorooctanoate in rats and human relevance

Clinically-approved Magnetic Resonance Imaging (MRI) contrast agents (CAs) are Gd-based small-molecule chelates which possess high thermodynamic stability and kinetic inertness in vivo. Free Gd3 + ion in plasma is toxic and has been implicated in Nephrogenic Systemic Fibrosis (NSF) in renally-compromised patients. Any preparation of Gd-based MRI CAs must therefore be carefully examined for the presence of free Gd3 + ion. A simple assay involves the use of Xylenol Orange (XO) as a colorimetric indicator under slightly acidic (pH = 5.8) buffered conditions. However, the structure of XO suggests that other ions possessing similar ionic size and/or coordination number could form complexes with XO as well. In this study, we investigated the complexation of XO with other metal ions, namely, Ca2 +, Mn2 +, Zn2 + and Tb3 +, by UV–Vis absorption spectroscopy and compared these results with those of Gd–XO solutions. Ligand-to-metal ratios were determined using Job plots, and the relative stabilities of the complexes were investigated by competition with EDTA. In summary, XO can be used to detect Gd3 +, Tb3 + and Zn2 + at the same concentration (< 1 μM) range, but not Mn2 + and Ca2 + which form M–XO only at higher concentrations. This discrepancy was rationalized by differences in ion charge density. Hence, XO can be used to discriminate between, for example, Gd3 + and Ca2 +, but not between Gd3 +, Tb3 + or Zn2 +.

Oral two-generation reproduction study with NM-200 synthetic amorphous silica in Wistar rats

Oral two-generation reproduction study with NM-200 synthetic amorphous silica in Wistar rats

Male reproductive system parameters in a two-generation reproduction study of ammonium perfluorooctanoate in rats and human relevance

Ammonium perfluorooctanoate (ammonium PFOA) is an industrial surfactant that has been used primarily as a processing aid in the manufacture of fluoropolymers. The environmental and metabolic stability of PFOA together with its presence in human blood and long elimination half-life have led to extensive toxicological studies in laboratory animals. Two recent publications based on observations from the Danish general population have reported: (1) a negative association between serum concentrations of PFOA in young adult males and their sperm counts and (2) a positive association among women with time to pregnancy. A two-generation reproduction study in rats was previously published (2004) in which no effects on functional reproduction were observed at doses up to 30 mg ammonium PFOA/kg body weight. The article contained the simple statement: “In males, fertility was normal as were all sperm parameters”. In order to place the recent human epidemiological data in perspective, herein we provide the detailed male reproductive parameters from that study, including sperm quality and testicular histopathology. Sperm parameters in rats from the two-generation study in all ammonium PFOA treatment groups were unaffected by treatment with ammonium PFOA. These observations reflected the normal fertility observations in these males. No evidence of altered testicular and sperm structure and function was observed in ammonium PFOA-treated rats whose mean group serum PFOA concentrations ranged up to approximately 50,000 ng/mL. Given that median serum PFOA in the Danish cohorts was approximately 5 ng/mL, it seems unlikely that concentrations observed in the general population, including those recently reported in Danish general population, could be associated causally with a real decrement in sperm number and quality.

A two-generation oral gavage reproduction study with potassium perfluorobutanesulfonate (K +PFBS) in Sprague Dawley rats

Perfluorobutanesulfonate (PFBS) is a surfactant and degradation product of substances based on perfluorobutanesulfonyl fluoride. A two-generation reproductive rat study has been conducted with potassium PFBS (K +PFBS). Parental-generation (P) rats were dosed orally by gavage with 0, 30, 100, 300 and 1000 mg K +PFBS/kg/day for 10 weeks prior to and through mating (males and females), as well as during gestation and lactation (females only). First generation (F1) pups were dosed similarly, beginning at weaning. Second generation (F2) pups were not directly dosed but potentially exposed to PFBS through placental transfer and nursing, and the study was terminated 3 weeks after their birth. Endpoints evaluated included body weight, food consumption, clinical signs, estrus cycling, sperm quality, pregnancy, natural delivery, litter outcomes, and developmental landmarks. The no-observable-adverse effect dose level (NOAEL) in the parental generations (P and F1) was 100 mg/kg/day. In the 300 and 1000 mg/kg/day dose group rats, there were (1) increased liver weight (absolute or relative) and corresponding increased incidence of adaptive hepatocellular hypertrophy (male only) and (2) increased incidence of minimal to mild microscopic findings in the medulla and papilla of the kidneys (male and female). There were no K +PFBS treatment-related effects on fertility or reproduction among the P or the F1 rats. There were no microscopic changes in male or female reproductive organs, and no biologically relevant effects on sperm parameters, mating, estrous cycles, pregnancy, and natural delivery in the P- or F1-generations. There were no K +PFBS treatment-related effects on survival of pups in the two-generation study. Litter size and average pup birth weight per litter were not statistically significantly different from controls in any dose group. In the F1-generation, terminal body weight was reduced in males at 1000 mg/kg/day. Preputial separation was slightly delayed (approximately 2 days) at this dose, a finding consistent with the body weight reduction. Essentially no effects were observed in the F1 females. F2 pups had normal body weights. The reproductive NOAEL was >1000 mg/kg/day in both generations.

Two-Generation Reproductive Toxicity Study of Resorcinol Administered Via Drinking Water to Crl:CD(SD) Rats

The potential adverse effects of resorcinol, delivered via drinking water at 0, 120, 360, 1000, and 3000 mg/L (palatability limit), were assessed in a regulatory guideline compliant two-generation reproduction study in Crl:CD(SD) rats. Expanded end points of thyroid gland (TG) function were added because of clinical case reports indicating human TG toxicity. Average daily resorcinol intake (mg/kg) at the 3000 mg/L concentration was 233 in F0 and F1 males, whereas in females it was 304 (premating/gestation) and 660 (lactation). No resorcinol ingestion-related clinical signs of toxicity were observed. Furthermore, neither gross morphologic anomalies nor effects on reproductive function or thyroid hormone levels were detectable. Body weight reductions occurred in 3000 mg/L F0 and F1 animals and were more pronounced in males. However, there was no evidence of either cumulative toxicity in the second generation or of enhanced sensitivity to resorcinol in pregnant/lactating females. Water intake was lower in 3000 mg/L rats of both generations and intermittently, to a lesser extent, at 1000 mg/L; however, concurrent feed intake and utilization were unaffected. Decreased TG follicular colloid content (conventional histopathology; confirmed by quantitative stereomicroscopy) in the 3000 mg/L F0 males was attributed to resorcinol but not considered adverse. The 3000 mg/L intake level appeared to have caused an adaptive thyroid response to a new homeostatic level with no adverse physiological consequences in either males (the more susceptible gender) or females. There were no differences in TG histology in F0 rats of either sex at 1000 mg/L. Thus, resorcinol intake at maximum palatability via a route and mode relevant to potential human exposures via contaminated drinking water at presently unknown environmental concentrations caused no detectable adverse effects on any reproduction or TG end points. The 3000 mg/L resorcinol exposure level was the no-observed-adverse-effect level (NOAEL) for parental systemic and offspring toxicity, while 1000 mg/L was the no-observed-effect level (NOEL).

A two-generation reproductive toxicity study of decamethylcyclopentasiloxane (D 5) in rats exposed by whole-body vapor inhalation

This two-generation reproduction study assessed the reproductive hazard potential of decamethylcyclopentasiloxane (D 5). Sprague–Dawley rats (30/sex/group) were exposed by whole-body vapor inhalation to a target concentration of 30, 70, or 160 ppm D 5 or filtered air for 6 h/day. Exposures for the F 0 and F 1 generations started at least 70 days prior to mating and lasted through weaning of the respective pups on postnatal day (PND) 21. Female exposures were interrupted from gestation day (GD) 21 through PND 4 to allow for parturition and to permit continuous maternal care for the early neonates. F 2 pups were not directly exposed to D 5. There were no exposure-related mortalities, clinical signs of toxicity, or effects on body weight or food consumption. There were no treatment-related gross findings or organ weight effects at the F 0 and F 1 necropsies. Other than minimal alveolar histiocytosis in all exposed groups, there were no noteworthy microscopic findings. Reproductive parameters (number of days between pairing and mating, mating and fertility indices, gestation length, and parturition), spermatogenic parameters and ovarian primordial follicle counts and numbers of corpora lutea in the F 0 and F 1 parental animals were not significantly changed between treated and control groups. Mean live litter sizes, number of pups born, sex ratios, pup body weights, postnatal pup survival and general physical condition of offspring in each generation were not affected. The slight, but statistically significant, increase in the mean F 1 male pup AGD in the 160 ppm group was not considered to be related to treatment. Vaginal patency and balanopreputial separation were unchanged compared to controls. Thus, the No-Observed-Adverse-Effect-Level (NOAEL) for parental and reproductive toxicity was determined to be 160 ppm D 5.

Two-generation reproduction and cross-foster studies of perfluorooctanesulfonate (PFOS) in rats

Perfluorooctanesulfonate (PFOS) is a persistent acid found widely distributed in wildlife and humans. To understand the potential reproductive and developmental effects of PFOS, a two-generation reproduction study was conducted in rats. Male and female rats were dosed via oral gavage at dose levels of 0, 0.1, 0.4, 1.6, and 3.2 mg/(kg day) for 6 weeks prior to mating, during mating, and, for females, through gestation and lactation, across two generations. Due to substantial F 1 neonatal toxicity observed in the 1.6 and 3.2 mg/(kg day) groups, continuation into the second generation was limited to F 1 pups from the 0, 0.1, and 0.4 mg/(kg day) groups. No adverse effects were observed in F 0 females or their fetuses upon caesarean sectioning at gestation day 10. Statistically significant reductions in body-weight gain and feed consumption were observed in F 0 generation males and females at dose levels of 0.4 mg/(kg day) and higher, but not in F 1 adults. PFOS did not affect reproductive performance (mating, estrous cycling, and fertility); however, reproductive outcome, as demonstrated by decreased length of gestation, number of implantation sites, and increased numbers of dams with stillborn pups or with all pups dying on lactation days 1–4, was affected at 3.2 mg/(kg day) in F 0 dams. These effects were not observed in F 1 dams at the highest dose tested, 0.4 mg/(kg day). Neonatal toxicity in F 1 pups, as demonstrated by reduced survival and body-weight gain through the end of lactation, occurred at a maternal dose of 1.6 mg/(kg day) and higher while not at dose levels of 0.1 or 0.4 mg/(kg day) or in F 2 pups at the 0.1 or 0.4 mg/(kg day) dose levels tested. In addition to these adverse effects, slight yet statistically significant developmental delays occurred at 0.4 (eye opening) and 1.6 mg/(kg day) (eye opening, air righting, surface righting, and pinna unfolding) in F 1 pups. Based on these data, the NOAELs were as follows: reproductive function: F 0 ≥ 3.2 and F 1 ≥ 0.4 mg/(kg day); reproductive outcome: F 0 = 1.6 and F 1 ≥ 0.4 mg/(kg day); overall parental effects: F 0 = 0.1 and F 1 ≥ 0.4 mg/(kg day); offspring effects: F 0 = 0.4 and F 1 ≥ 0.4 mg/(kg day). To distinguish between maternal and pup influences contributing to the perinatal mortality observed in the two-generation study, a follow-up cross-foster study was performed. Results of this study indicated that in utero exposure to PFOS causally contributed to post-natal pup mortality, and that pre-natal and post-natal exposure to PFOS was additive with respect to the toxic effects observed in pups.

Neonatal mortality from in utero exposure to perfluorooctanesulfonate (PFOS) in Sprague–Dawley rats: Dose–response, and biochemical and pharamacokinetic parameters

Perfluorooctanesulfonate (PFOS) is a widely distributed, environmentally persistent acid found at low levels in human, wildlife, and environmental media samples. Neonatal mortality has been observed following PFOS exposure in a two-generation reproduction study in rats and after dosing pregnant rats and mice during gestation. Objectives of the current study were to better define the dose–response curve for neonatal mortality in rat pups born to PFOS-exposed dams and to investigate biochemical and pharmacokinetic parameters potentially related to the etiology of effects observed in neonatal rat pups. In the current study, additional doses of 0.8, 1.0, 1.2, and 2.0 mg/kg/day were included with original doses used in the two-generation study of 0.4 and 1.6 mg/kg/day in order to obtain data in the critical range of the dose–response curve. Biochemical parameters investigated in dams and litters included: (1) serum lipids, glucose, mevalonic acid, and thyroid hormones; (2) milk cholesterol; and (3) liver lipids. Pharmacokinetic parameters investigated included the interrelationship of administered oral dose of PFOS to maternal body burden of PFOS and the transfer of maternal body burden to the fetus in utero and pup during lactation, as these factors may affect neonatal toxicity. Dosing of dams occurred for 6 weeks prior to mating with untreated breeder males, through confirmed mating, gestation, and day four of lactation. Dose levels for the dose–response and etiological investigation were 0.0, 0.4, 0.8, 1.0, 1.2, 1.6, and 2.0 mg/kg/day PFOS. Statistically significant decreases in gestation length were observed in the 0.8 mg/kg and higher dose groups. Decreases in viability through lactation day 5 were observed in the 0.8 mg/kg and higher dose groups, becoming statistically significant in the 1.6 and 2.0 mg/kg dose groups. Reduced neonatal survival did not appear to be the result of reductions in lipids, glucose utilization, or thyroid hormones. The endpoints of gestation length and decreased viability were positively correlated, suggesting that late-stage fetal development may be affected in pups exposed to PFOS in utero and may contribute to the observed mortality. Benchmark dose (BMD) estimates for decreased gestation length, birth weight, pup weight on lactation day 5, pup weight gain through lactation day 5, and viability resulted in values ranging from 0.27 to 0.89 mg/kg/day for the lower 95% confidence limit of the BMD 5 (BMDL 5). Results of analyses for PFOS in biological matrices indicate a linear proportionality of mean serum PFOS concentration to maternal administered dose prior to mating and through the first two trimesters of gestation. However, at 21 days of gestation, mean serum PFOS concentrations were notably reduced from values measured earlier in gestation. Urinary and fecal elimination was low as expected from prior observations in adult rats. Significant transfer of PFOS from dam to fetus in utero was confirmed, and results suggest that dam and corresponding fetal body burdens, as indicated by serum and liver PFOS levels, correlate with neonatal survival.

Proposals for nutritional assessments of feeds from genetically modifed plants

2. A two-generation reproduction study with transgenic Bt rice TT51 in Wistar rats Er Hui Wang, Zhou Yu, Jing Hu, Xu Dong Jia, Hai Bin Xu Food and Chemical Toxicology CrossRef

Amended Final Report on the Safety Assessment of Polyacrylamide and Acrylamide Residues in Cosmetics1

Polyacrylamide is a polymer of controllable molecular weight formed by the polymerization of acrylamide monomers available in one of three forms: solid (powder or micro beads), aqueous solution, or inverse emulsions (in water droplets coated with surfactant and suspended in mineral oil). Residual acrylamide monomer is likely an impurity in most Polyacrylamide preparations, ranging from <1 ppm to 600 ppm. Higher levels of acrylamide monomers are present in the solid form compared to the other two forms. Polyacrylamide is reportedly used in 110 cosmetic formulations, at concentrations ranging from 0.05% to 2.8%. Residual levels of acrylamide in Polyacrylamide can range from <.01% to 0.1%, although representative levels were reported at 0.02% to 0.03%. Because of the large sizes of Polyacrylamide polymers, they do not penetrate the skin. Polyacrylamide itself is not significantly toxic. For example, an acute oral toxicity study of Polyacrylamide in rats reported that a single maximum oral dose of 4.0 g/kg body weight was tolerated. In subchronic oral toxicity studies, rats and dogs treated with Polyacrylamide at doses up to 464 mg/kg body weight showed no signs of toxicity. Several 2-year chronic oral toxicity studies in rats and dogs fed diets containing up to 5% Polyacrylamide had no significant adverse effects. Polyacrylamide was not an ocular irritant in animal tests. No compound-related lesions were noted in a three-generation reproductive study in which rats were fed 500 or 2000 ppm Polyacrylamide in their diet. Polyacrylamide was not carcinogenic in several chronic animal studies. Human cutaneous tolerance tests performed to evaluate the irritation of 5% (w/w) Polyacrylamide indicated that the compound was well tolerated. Acrylamide monomer residues do penetrate the skin. Acrylamide tested in a two-generation reproductive study at concentrations up to 5 mg/kg day(- 1) in drinking water, was associated with prenatal lethality at the highest dose, with evidence of parental toxicity. The no adverse effects level was close to the 0.5 mg/kg day(- 1) dose. Acrylamide tested in a National Toxicology Program (NTP) reproductive and neurotoxicity study at 3, 10, and 30 ppm produced no developmental or female reproductive toxicity. However, impaired fertility in males was observed, as well as minimal neurotoxic effects. Acrylamide neurotoxicity occurs in both the central and peripheral nervous systems, likely through microtubule disruption, which has been suggested as a possible mechanism for genotoxic effects of acrylamide in mammalian systems. Acrylamide was genotoxic in mammalian in vitro and in vivo assays. Acrylamide was a tumor initiator, but not an initiator/promoter, in two different mouse strains at a total dose of 300 mg/kg (6 doses over 2 weeks) resulting in increased lung adenomas and carcinomas without promotion. Acrylamide was tested in two chronic bioassays using rats. In one study, increased incidence of mammary gland tumors, glial cell tumors, thyroid gland follicular tumors, oral tissue tumors, uterine tumors and clitoral gland tumors were noted in female rats. In male rats, the number of tumors in the central nervous system (CNS), thyroid gland, and scrotum were increased with acrylamide exposure. In the second study, using higher doses and a larger number of female rats, glial cell tumors were not increased, nor was there an increase in mammary gland, oral tissue, clitoral gland, or uterine tumors. Tumors of the scrotum in male rats were confirmed, as were the thyroid gland follicular tumors in males and females. Taken together, there was a dose-dependent, but not statistically significant, increase in the number of astrocytomas. Different human lifetime cancer risk predictions have resulted, varying over three orders of magnitude from 2 x 10(- 3) to 1.9 x 10(- 6). In the European Union, acrylamide has been limited to 0.1 ppm for leave-on cosmetic products and 0.5 ppm for other cosmetic products. An Australian risk assessment suggested negligible health risks from acrylamide in cosmetics. The Cosmetic Ingredient Review (CIR) Expert Panel acknowledged that acrylamide is a demonstrated neurotoxin in humans and a carcinogen in animal tests, but that neurotoxic levels could not be attained by use of cosmetics. Although there are mechanisms of action of acrylamide that have been proposed for tumor types seen in rat studies that suggest they may be unique to the rat, the Panel was not convinced that these results could be disregarded as a species-specific finding with no relevance to human health and safety. Based on the genotoxicity and carcinogenicity data, the Panel does not believe that acrylamide is a genotoxic carcinogen in the usual manner and that several of the risk assessment approaches have overestimated the human cancer risk. The Panel did conclude, however, that it was appropriate to limit acrylamide levels to 5 ppm in cosmetic formulations.

A two-generation reproduction study to assess the effects of cows' milk on reproductive development in male and female rats

To examine whether the considerable quantities of increased female sex hormone levels found in modern milk as a result of modern dairy farming practices are safe for human consumption. Males and females of the P generation were maintained on a diet containing milk for 10 weeks before mating. Exposure to milk was continued up to the end of weaning of the F2b offspring. Two-generation reproduction study. Male and female Wistar Galas rats. P- and F1-generation rats were mated. Fertility, fecundity, and morphology and function of reproductive organs. Although milk had growth-promoting effects in both parents and offspring, it caused no impairments in fertility, fecundity, or reproductive organ development in either generation. However, a whole litter from a dam of the P generation was born dead, three litters in total had a pup with skeletal abnormalities, and the AGD of F2a female pups was reduced. These events occurred only in the milk-treated rats. It is unknown whether these issues had any relevance to milk or only happened by chance. Further study is required to determine whether milk from pregnant cows is completely free from adverse effects on reproductive health.

Review of the toxicology, human exposure and safety assessment for bisphenol A diglycidylether (BADGE)

BADGE (whose chemical names are bisphenol A diglycidylether and 2,2-bis(4-(2,3-epoxypropyl)phenyl)propane) is the lowest molecular weight oligomer in commercial epoxy resins and the major component in commercial liquid epoxy resins. The major application areas for epoxy resins are protective coatings and civil engineering. Additional applications include printed circuit boards, composites, adhesives and tooling, while a relatively small amount of epoxy resins (<10%) finds use in protective coatings inside food and drink cans. The use of BADGE in food-contact applications was first regulated through EC Directive 2002/16/EC and amended in EC Directive 2004/13/EC with migration levels in food-contact applications being generally well below the regulatory thresholds. The paper discusses the commercial use of BADGE focusing on the current knowledge of human exposure from canned food applications. To assess the safety of this application, the exposure data are compared with no adverse effect levels (NOAEL) from various toxicological investigations with BADGE including reproductive and developmental assays, endocrine toxicity investigations, and sub-chronic and chronic assays. Consumer exposure to BADGE is almost exclusively from migration of BADGE from can coatings into food. Using a worst-case scenario that assumes BADGE migrates at the same level into all types of food, the estimated per capita daily intake for a 60-kg individual is approximately 0.16 μg kg−1 body weight day−1. A review of one- and two-generation reproduction studies and developmental investigations found no evidence of reproductive or endocrine toxicity, the upper ranges of dosing being determined by maternal toxicity. The lack of endocrine toxicity in the reproductive and developmental toxicological tests is supported by negative results from both in vivo and in vitro assays designed specifically to detect oestrogenic and androgenic properties of BADGE. An examination of data from sub-chronic and chronic toxicological studies support a NOAEL of 50 mg kg−1 body weight day−1 from the 90-day study, and a NOAEL of 15 mg kg−1 body weight day−1 (male rats) from the 2-year carcinogenicity study. Both NOAELS are considered appropriate for risk assessment. Comparing the estimated daily human intake of 0.16 μg kg−1 body weight day−1 with the NOAELS of 50 and 15 mg kg−1 body weight day−1 shows human exposure to BADGE from can coatings is between 250 000 and 100 000-fold lower than the NOAELs from the most sensitive toxicology tests. These large margins of safety together with lack of reproductive, developmental, endocrine and carcinogenic effects supports the continued use of BADGE for use in articles intended to come into contact with foodstuffs.

Inhalation two-generation reproductive toxicity study of methyl isobutyl ketone in rats.

To evaluate whether methyl isobutyl ketone (MIBK) affects reproductive performance, a two-generation reproduction study was conducted. MIBK was administered to 30 Sprague-Dawley rats/sex/group via whole-body inhalation at concentrations of 0, 500, 1000, or 2000 ppm, 6 h daily, for 70 days prior to mating. F(0) and F(1) females were exposed from mating through gestation day 20 and from postnatal day 5; F(2) litters were maintained through postnatal day 21. No treatment-related mortality of adult animals occurred. There was a dose-related increase in adult animals with no or a decreased response to a sound stimulus at 1000 and 2000 ppm; however, no adverse clinical signs occurred 1 h after exposure, suggesting this was a transient sedative effect. Clinical signs of central nervous system (CNS) depression in the pups were observed and one F(1) pup died after initial exposure to 2000 ppm on postnatal day 22; subsequently exposure was delayed until postnatal day 28. Decreased body weight gain and slight decreased food consumption were observed during the first 2 weeks of exposure in both generations at 2000 ppm. There were no adverse effects on male and female reproductive function or landmarks of sexual maturation. Increased F(0) and F(1) liver weights with associated centrilobular hypertrophy occurred in rats at 2000 ppm, indicative of an adaptive response. Increased male kidney weights at all exposure concentrations, associated with hyaline droplets, were indicative of male rat-specific nephropathy. Other than acute sedative effects, the no-observed-adverse-effect level (NOAEL) for parental systemic effects (excluding male rat kidney) was 1000 ppm, based on transient decreased body weight and food consumption; for reproductive effects, 2000 ppm, the highest concentration tested; and for neonatal toxicity, 1000 ppm (based on acute CNS depressive effects).