Prenatal blood levels of some toxic metals and the risk of spontaneous abortion.

High-level toxic metal exposure has become rare in the recent years. Although, it has not known whether relatively lower exposure may adversely affect human reproductive system. Spontaneous abortion (SA) is a serious reproductive problem, which, in many cases, the cause(s) is not clearly understood. To assess the relationship between prenatal blood level of metals and SA risk, we compared blood concentration of some heavy metals in samples taken from mothers recruited in Tehran Environment and Neurodevelopmental Defects (TEND) study conducted on apparently healthy pregnant women in Tehran, Iran who subsequently experienced spontaneous abortion with mothers who their pregnancy ended to live births. During early gestation, 206 women were enrolled to the survey and followed up till fetal abortion or baby deliveries occur. Blood metal concentrations were measured using an inductively coupled plasma mass spectrometer. The mean blood levels of lead, antimony, and nickel were higher in SA than ongoing pregnancy; however, this difference was not statistically significant. When adjusted for covariates, the logistic regression analysis showed significant association between maternal age and the risk of SA in all models. Among toxic metals only antimony had a noticeable positive relation with the risk of SA (OR: 1.65, 95% CI:1.08-2.52, P value: 0.02). Pearson's correlation coefficient showed significant (P < 0.05) positive correlations among prenatal blood metals levels, except for nickel. Although the present study failed to provide strong evidence for the effects of toxic metals on the occurrence of SA at the relatively low-levels, these metals should be avoided in women who plan pregnancy and/or during the early stages of gestation to prevent the chance of adverse effects.

Hair Metal Levels and Childhood Weight Gain.

BACKGROUND: Exposure to toxic metals remains a public health problem with lifelong impacts on childhood growth and development. We aimed to investigate metals effects on preschool children's anthropometric variables. METHODS: The study was conducted in Tehran, Iran, from Jul 2013 to Mar 2016. We measured scalp hair metal concentrations (lead, cadmium, arsenic, zinc, manganese, and cobalt), using inductively coupled plasma mass spectrometry, in 207 preschool children's (36 to 72 months old). RESULTS: A significant negative correlation between children's hair lead levels and children's weight was found (r= -0.178, P<0.05). Linear regression analysis confirmed the relationship when adjusted for the confounders, including children's age, sex, height, family income, and maternal education (ß= -0.191; t= -3.426, P< 0.01). The ANOVA analysis showed a significant (P<0.01) difference between hair lead level and children's weight-for-age percentiles. Totally and separately, in almost all weight percentiles, hair lead levels were higher in girls than boys. CONCLUSION: The present study on Iranian children showed the current levels of lead exposure might negatively influence on children growth, with higher risk for girls than boys.

Biphasic adverse effect of titanium nanoparticles on testicular function in mice.

The male reproductive system is being recognized as toxic targets of nanoparticles including titanium dioxide nanoparticles (TiNP). Most of these reports are, however, obtained from the results of long-term exposure of TiNP. In this study, we diversely examined the acute effects of TiNP on the male reproductive system. Male C57BL/6J mice were administered a single intravenous injection of TiNP (10, 50 mg/kg), and were sacrificed at 1, 3, and 9 days post-injection. Testicular functions (estimated by sperm motility and sperm number) were measured via computer-assisted sperm analysis (CASA). Results indicated that sperm motility was significantly reduced from 1 day following TiNP injection (in both dose), and this reduction persisted up to 9 days post-TiNP injection (10 mg/kg injection group). Interestingly, we observed no significant decrease in sperm numbers in both the testis and the cauda epididymis in either treatment groups during the course of the experiment. Therefore, we hypothesized that TiNP may target the mature spermatozoa. In addition, sperm suspensions directly incubated with TiNP showed reduced sperm motility, [3H]-thymidine incorporation, and ATP level. Our results indicated that TiNP possesses "biphasic effects"; the obstacles to mature sperms (short term effect) in addition to the impairment in testis (long-term effect).

Lethal chronotoxicity induced by seven metal compounds in mice.

The aim of the present study is to investigate the "chronotoxicity" of seven metal compounds (Hg, Pb, Ni, Cr, Cu, Zn, or Fe) by assessing how their toxicity varies with circadian periodicity. Male ICR mice were injected with each metal compound intraperitoneally at 6 different time points over the course of a day (zeitgeber time [ZT]: ZT2, ZT6, ZT10, ZT14, ZT18 and ZT22). Mortality was then monitored until 14 days after the injection. Our investigation demonstrated that mice were tolerant against Ni toxicity during dark phase, on the other hand, they were tolerant against Cr toxicity during light phase. The chronotoxicity of Hg and Pb seemed to be biphasic. Further, mice were susceptible to toxicities against Cu and Zn in the time zone during which light and dark were reversed. Interestingly, no significant differences were observed for Fe exposure at any time of the day. Our results propose that the chronotoxicology may provide valuable information regarding the importance of injection timing for not only toxicity evaluation tests but also the reproducibility of animal experiments. Furthermore, our data suggests that chronotoxicology may be an important consideration when evaluating the quality of risk assessments for night shift workers who may be exposed to toxic substances at various times of the day.

Epididymal phospholipidosis is a possible mechanism for spermatotoxicity induced by the organophosphorus insecticide fenitrothion in rats.

Fenitrothion (FNT) is used worldwide in agricultural and public health settings. Spermatogenesis is a toxicological target of FNT under high-dose exposure. Although anti-androgenic action is postulated to be the mechanism associated with this toxicity, few studies have examined histopathology of androgen-dependent male accessory sex organs. The present study aimed to reveal the effects of FNT on the accessory organs of rats exhibiting spermatotoxicity in the absence of testicular histopathological changes. Furthermore, a possible novel molecular target was clarified. Male Wistar rats were orally administered 5 or 10 mg/kg FNT or its major metabolite 3-methyl-4-nitrophenol (MNP), or vehicle only, 4 days per week for 9 weeks. Then the epididymis, prostate, and seminal vesicles were collected. FNT and MNP did not show anti-androgenic effects but FNT induced cytoplasmic vacuolation in the epithelial cells of epididymal ducts and hyperplasia of mucosal folds/epithelial papillomatosis in seminal vesicles. FNT and MNP induced epididymal phospholipidosis, which was presumably caused by inhibition of epididymal secreted phospholipase A2 (sPLA2). Percentages of morphologically normal sperm and immature sperm were significantly predicted from both epididymal sPLA2 and phospholipid levels and from epididymal sPLA2, respectively. These results suggest that epididymal phospholipidosis plays an important role in FNT-induced spermatotoxicity. Anti-androgenic actions were not observed.

Prenatal mercury exposure and birth weight.

Adverse effects of prenatal mercury exposure on pregnancy outcomes remain a public health concern. We assessed the relationship between prenatal mercury exposure and newborn anthropometric characteristics in 334 mother-child pairs from the early stages of pregnancy to delivery in Tokyo, Japan, between December 2010 and October 2012. We found a negative correlation between blood mercury levels during the first and second trimesters of gestation and birth weight (r = -0.134 and -0.119, respectively; p < 0.05). Multiple linear regression analysis confirmed the relationship between first-trimester maternal blood mercury levels and birth weight when adjusted for independent variables (ß = -0.170, t = -2.762; p = 0.006). Mean mercury levels in umbilical cord blood were twice as high as maternal blood levels (10.15 ±â€¯7.74 and 4.97 ±â€¯3.25 µg/L, respectively; r = 0.974, p < 0.001). Our findings suggest that pregnant women and women of reproductive age should avoid mercury exposure, even at low levels, because of its potentially adverse effects on fetal development.

Multidirectional analyses of hepatic chronotoxicity induced by cadmium in mice.

The expression levels or activities of biological defense factors can fluctuate daily following biological rhythms. We have focused on the relationship between injection timing and the degree of toxicity of cadmium (Cd) to promote the concept of "chronotoxicology," which introduces chronobiology to the field of toxicology. Our previous studies have clearly indicated that Cd may be subject to chronotoxicity. In this report, to confirm the character of the Cd-induced chronotoxicity, we performed multidirectional examinations. Male C57BL/6J mice that received a single intraperitoneal injection of CdCl2 at ZT6 showed drastic hepatic injury estimated by histopathological analyses, i.e., nuclear condensations, fatty degenerations, and hemorrhages, but showed no injury when injected at ZT18. This difference was supported by several biochemical analyses that were indicators of hepatic injury (levels of alanine aminotransferase, aspartate aminotransferase, and malondialdehyde). The chronotoxicity of Cd was also observed in multiple strains (ICR and Balb/c), in a different injection route (subcutaneous), and in multiple injections (5 injections). Based on these results, we propose that chronotoxicology may provide important information not only for toxicology but also for occupational health, i.e., the importance of injection timing for toxicity evaluation tests, the reproducibility of animal experiments, and the improvement in the quality of risk assessments for night shift workers who may be exposed to toxic substances at various times of the day.

Effects of Hair Metals on Body Weight in Iranian Children Aged 20 to 36 Months.

BACKGROUND: Although the level of exposure to many toxic metals decreased recently, the adverse effects of these metals on children's growth and development remain a serious public health issue. METHODS: The present study was conducted in three teaching hospitals affiliated with Tehran University of Medical Sciences (Tehran, Iran) from Sep 2012 to Mar 2013. To study the relationship between metals and childhood growth, concentrations of zinc and several potentially toxic metals (lead, cadmium, antimony, cobalt, and molybdenum) were measured in scalp hair for 174 children, aged 20 to 36 months. RESULTS: The hair concentrations of cobalt were significantly (P<0.05) higher in children at the lower percentile of weight than in higher-weight children (0.026 ± 0.04 vs. 0.015 ± 0.01 µg/g, respectively). Hair contents of lead, cobalt, and antimony were significantly higher (P<0.05) in girls than in boys (8.08 ± 8.7 vs. 4.92 ± 5.6 µg/g for lead, 0.026 ± 0.03 vs. 0.16 ± 0.02 µg/g for cobalt, and 0.188 ± 0.29 vs. 0.102 ± 0.12 µg/g for antimony). There were also significant correlations between lead and other metals in the children's hair. CONCLUSION: Gender may play a significant role in absorption and/or accumulation of metals. It should be considered when we study metal toxicity in children.

High sensitivity of testicular function to titanium nanoparticles.

Titanium dioxide nanoparticles (TiNPs) present toxicity in organs such as the liver, lung, and intestine. The testis has also been reported as a target organ of TiNPs. We recently reported that TiNPs had no genotoxic effect in the liver and bone marrow, while showing clear testicular dysfunction. In this paper, therefore, we systematically compared the sensitivity of hepatic function using biochemical markers and testicular function against TiNPs. Male C57BL/6J mice were injected intravenously with TiNPs (Aeroxide-P25, at doses of 0.1, 1, 2, and 10 mg/kg body weight) once per week for 4 consecutive weeks. Mice were sacrificed three days after the last injection. Body weights, liver weights, and testicular-related organ weights were not found to be changed by TiNP treatment. Moreover, TiNPs caused no hepatic damage, as evaluated by alanine aminotransferase and aspartate aminotransferase indexes. The testicular function, however, was clearly impaired by TiNP treatment; reduction in two sperm motion parameters (motile percent and progressive percent) and sperm numbers in cauda epididymides was seen. We observed Ti accumulation in the liver but not in the testis, as well as no change in plasma levels of sex hormones related to spermatogenesis. Our findings indicate that the testis is highly sensitive to TiNPs, as compared to the liver. We believe that, when considering the biological effects of TiNPs, testicular function (especially motility ability) may be a sensitive indicator.

Chronotoxicity of bromobenzene-induced hepatic injury in mice.

The aim of the present study is to investigate whether or not bromobenzene (BB) toxicity varies with circadian periodicity. Seven-week-old male ICR mice were injected with 900 mg/kg (5.73 mmol/kg) BB intraperitoneally at 4 different time points of a day (zeitgeber time [ZT]: ZT0, ZT6, ZT12, and ZT18). Mortality was then monitored for 7 days after injection. Interestingly, mice were sensitive to BB acute toxicity at ZT6 while tolerant at ZT18. Moreover, in mice that were given a non-lethal dose of BB (540 mg (3.44 mmol)/kg), levels of alanine aminotransferase and aspartate aminotransferase, used as markers of hepatic injury, markedly increased in response to injection at ZT6, but did not increase significantly in response to injection at ZT18. In contrast, the markers of renal injury (creatinine and blood urea nitrogen), showed no significant difference in response to the two injection times. To further investigate this extreme circadian variation, we examined hepatic and renal lipid peroxidation levels, and conducted histopathological studies. Similar to our observation with alanine aminotransferase and creatinine, hepatic lipid peroxidation and histopathological changes were more pronounced than renal changes, and showed circadian variation. Our present investigation demonstrated that BB-induced mortality had clear circadian variation, and suggested that hepatic injury was one of the important factors for determination of this variation.

Increased prenatal blood manganese may induce gestational blood pressure.

OBJECTIVE: Pregnancy hypertension is the most common gestational complication and poses a critical risk for mother and fetus. Whether environmental factors may play an important role in disease occurrence is not fully determined. METHODS: To investigate the effects of prenatal manganese (Mn) exposure on gestational blood pressure, 386 women were examined. RESULTS: Early pregnancy blood Mn was significantly (p < 0.05) correlated with blood pressure through gestation. A significant association between odds of pre-hypertension with blood Mn was shown (OR:1.150, 95% CI:1.052-1.258). CONCLUSION: The current study results might suggest the blood Mn level during early stage of pregnancy as a potential risk factor for increasing the risk of gestational blood pressure.

The relation of maternal blood arsenic to anemia during pregnancy.

To clarify the relationship of prenatal arsenic exposure to hemoglobin concentrations and anemia during pregnancy, a longitudinal study was conducted of 364 participants during early pregnancy from October 2006 to March 2011 in Tehran, Iran. Maternal whole blood (taken between 8-12 and 20-24 weeks of gestation, and at delivery) and umbilical cord blood samples were collected for arsenic measurement. The mean concentration of maternal blood arsenic in the first trimester of pregnancy was significantly lower in anemic women compared with non-anemic participants (mean ± SD: 12.4 ± 3.4 versus 14.8 ± 4.0 µg/L, respectively, p < 0.001). Maternal whole blood arsenic levels in the first and third trimesters were significantly (p < 0.05) correlated with hemoglobin concentrations measured throughout gestation (r = 0.312, 0.424, and 0.183). Multiple logistic regression analysis demonstrated that increased maternal blood arsenic levels in the first trimester were significantly negatively associated to anemia during pregnancy (OR = 0.85, CI: 0.77-0.94, p < 0.01). The present study showed that prenatal blood arsenic exposure was not a risk factor for the occurrence of anemia.

Fenitrothion action at the endocannabinoid system leading to spermatotoxicity in Wistar rats.

Organophosphate (OP) compounds as anticholinesterase agents may secondarily act on diverse serine hydrolase targets, revealing unfavorable physiological effects including male reproductive toxicity. The present investigation proposes that fenitrothion (FNT, a major OP compound) acts on the endocannabinoid signaling system in male reproductive organs, thereby leading to spermatotoxicity (sperm deformity, underdevelopment, and reduced motility) in rats. FNT oxon (bioactive metabolite of FNT) preferentially inhibited the fatty acid amide hydrolase (FAAH), an endocannabinoid anandamide (AEA) hydrolase, in the rat cellular membrane preparation from the testis in vitro. Subsequently, male Wistar rats were treated orally with 5 or 10mg/kg FNT for 9 weeks and the subchronic exposure unambiguously deteriorated sperm motility and morphology. The activity-based protein profiling analysis with a phosphonofluoridate fluorescent probe revealed that FAAH was selectively inhibited among the FNT-treated cellular membrane proteome in testis. Intriguingly, testicular AEA (endogenous substrate of FAAH) levels were elevated along with the FAAH inhibition caused by the subchronic exposure. More importantly, linear regression analyses for the FNT-elicited spermatotoxicity reveal a good correlation between the testicular FAAH activity and morphological indices or sperm motility. Accordingly, the present study proposes that the FNT-elicited spermatotoxicity appears to be related to inhibition of FAAH leading to overstimulation of the endocannabinoid signaling system, which plays crucial roles in spermatogenesis and sperm motility acquirement.

Low level prenatal blood lead adversely affects early childhood mental development.

The effect of prenatal lead exposure on child development has been a topic of public health concern for decades. To estimate prenatal lead exposure effects on early childhood development, maternal blood (n = 364) and umbilical cord blood (n = 224) samples were collected during pregnancy and at delivery. Mental development was assessed using the Harold Ireton Early Child Development Inventory from 174 children. Maternal whole blood lead levels in the first trimester were significantly higher in children with developmental scores <20% than in those with normal scores (mean ± standard deviation: 6.3 ± 1.9 vs 4.0 ± 2.4 µg/dL, respectively, P = .01). Maternal blood lead levels in the first trimester were also inversely associated with the development scores (r = -0.155, P = .041). Logistic regression analysis showed a significant relationship between increasing maternal blood lead levels in the first trimester with low development scores (odds ratio = 1.74, 95% confidence interval = 1.18-2.57, P = .005). The findings of the present study showed a relatively low level of prenatal lead exposure (mean < 6.5 µg/dL) associated with lower developmental scores in early childhood.

Assessment of the reproductive toxicity of inhalation exposure to ethyl tertiary butyl ether in male mice with normal, low active and inactive ALDH2.

No data are available regarding aldehyde dehydrogenase 2 (ALDH2) polymorphisms related to the reproductive toxicity possibly caused by ethyl tertiary butyl ether (ETBE). In this study, two inhalation experiments were performed in Aldh2 knockout (KO), heterogeneous (HT) and wild type (WT) C57BL/6 male mice exposed to ETBE, and the data about general toxicity, testicular histopathology, sperm head numbers, sperm motility and sperm DNA damage were collected. The results showed that the 13-week exposure to 0, 500, 1,750 and 5,000 ppm ETBE significantly decreased sperm motility and increased levels of sperm DNA strand breaks and 8-hydroxy-deoxyguanosine in both WT and KO mice, the effects were found in 1,750 and 5,000 ppm groups of WT mice, and all of the three exposed groups of KO mice compared to the corresponding control; furthermore, ETBE also caused decrease in the relative weights of testes and epididymides, the slight atrophy of seminiferous tubules of testis and reduction in sperm numbers of KO mice exposed to ≥500 ppm. In the experiment of exposure to lower concentrations of ETBE (0, 50, 200 and 500 ppm) for 9 weeks, the remarkable effects of ETBE on sperm head numbers, sperm motility and sperm DNA damage were further observed in KO and HT mice exposed to 200 ppm ETBE, but not in WT mice. Our findings suggested that only exposure to high concentrations of ETBE might result in reproductive toxicity in mice with normal active ALDH2, while low active and inactive ALDH2 enzyme significantly enhanced the ETBE-induced reproductive toxicity in mice, even exposed to low concentrations of ETBE, mainly due to the accumulation of acetaldehyde as a primary metabolite of ETBE.

Mechanisms of cadmium-induced chronotoxicity in mice.

Biological defense factors show diurnal variations in their expression levels or activities. These variations can induce the different sensitivity to external toxicants of a day. We reported earlier that mice showed clear diurnal variation of cadmium (Cd)-induced toxicity, i.e., chronotoxicity. In this report, we investigated additional new evidences for the cadmium (Cd)-induced chronotoxicity, and considered the mechanisms contributed to this chronotoxicity. Male C57BL/6J mice were injected with CdCl2 (6.4 mg/kg, one shot) intraperitoneally at 6 different time points of a day (zeitgeber time (ZT); ZT2, ZT6, ZT10, ZT14, ZT18 or ZT22) followed by monitoring the mortality until 14 days after the injection. We observed extreme difference in survival numbers: surprisingly, all mice died at ZT2 injection while all mice survived at ZT18 injection. Moreover, in non-lethal dose of Cd (4.5 mg/kg), the values of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) used as indexes of hepatotoxicity markedly increased at ZT6 injection while mostly unchanged at ZT18 injection. To consider the mechanisms of this extreme diurnal variation, we examined biochemical studies and concluded that the diurnal variation was not caused by the differences in hepatic Cd level, basal hepatic metallothionein (MT) level, and induction level or induction speed of hepatic MT. We suggested that one of the candidate determination factors was glutathione. We believe that the "chronotoxicology" for metal toxicity may be classic, yet new viewpoint in modern toxicology field.

Increase in blood manganese induces gestational hypertension during pregnancy.

OBJECTIVE: Pregnancy hypertension can lead to many pregnancy complications and increases the risk of maternal morbidity and mortality. METHODS: To investigate the effects of blood manganese (Mn) on the development of pregnancy hypertension, 364 healthy women were examined during early pregnancy until delivery. RESULTS: At the first and second trimesters of pregnancy, concentrations of Mn in maternal blood were significantly higher in the hypertensive pregnant women than in the normotensive women. The logistic regression analysis demonstrated significant relationships between Mn concentrations in maternal blood for the first and second trimesters of pregnancy with gestational hypertension [OR (95% CI) = 47.0 (4.0-556.4) and 5.5 (1.1-29.0), respectively]. CONCLUSION: The present study thus suggested that increased Mn during pregnancy might be a potential risk factor for inducing pregnancy hypertension.

Subchronic exposure to ethyl tertiary butyl ether resulting in genetic damage in Aldh2 knockout mice.

Ethyl tertiary butyl ether (ETBE) is biofuel additive recently used in Japan and some other countries. Limited evidence shows that ETBE has low toxicity. Acetaldehyde (AA), however, as one primary metabolite of ETBE, is clearly genotoxic and has been considered to be a potential carcinogen. The aim of this study was to evaluate the effects of ALDH2 gene on ETBE-induced genotoxicity and metabolism of its metabolites after inhalation exposure to ETBE. A group of wild-type (WT) and Aldh2 knockout (KO) C57BL/6 mice were exposed to 500ppm ETBE for 1-6h, and the blood concentrations of ETBE metabolites, including AA, tert-butyl alcohol and 2-methyl-1,2-propanediol, were measured. Another group of mice of WT and KO were exposed to 0, 500, 1750, or 5000ppm ETBE for 6h/day with 5 days per weeks for 13 weeks. Genotoxic effects of ETBE in these mice were measured by the alkaline comet assay, 8-hydroxyguanine DNA-glycosylase modified comet assay and micronucleus test. With short-term exposure to ETBE, the blood concentrations of all the three metabolites in KO mice were significantly higher than the corresponding concentrations of those in WT mice of both sexes. After subchronic exposure to ETBE, there was significant increase in DNA damage in a dose-dependent manner in KO male mice, while only 5000ppm exposure significantly increased DNA damage in male WT mice. Overall, there was a significant sex difference in genetic damage in both genetic types of mice. These results showed that ALDH2 is involved in the detoxification of ETBE and lack of enzyme activity may greatly increase the sensitivity to the genotoxic effects of ETBE, and male mice were more sensitive than females.

Influence of injection timing on severity of cadmium-induced testicular toxicity in mice.

Cadmium (Cd) is one of the endocrine disrupter and is a well-known testicular toxicant. Recently, we reported that Cd-induced mortality was markedly different by injection timing. In this report, we investigated whether severity of testicular toxicity was affected by injection timing of Cd. C57BL/6J mice (male, 7 w) were received single intraperitoneal injection of CdCl(2) (4.5 mg/kg) at zeitgeber time 6 (ZT6) or ZT18; these injection timings showed highest (ZT6) or lowest (ZT18) mortality in our previous study (Miura, 2012). After one week of the injection, several parameters for testicular toxicity such as epididymal sperm motility and numbers of sperm head both in cauda epididymidis and testis were measured. At ZT6 injection group, all parameters examined were significantly reduced compared to the control group. However, very interestingly, no significant changes were observed at ZT18 injection group. We obtained similar results by another experiment in which mice were received single subcutaneous injection of CdCl(2) (4 or 6 mg/kg) followed by measuring the parameters ten days after the injection. This diurnal variation was not contradictory to the result of the lethal toxicity which we showed earlier. Therefore, our results indicate that the testicular toxicity of Cd is also influenced by the injection timing.