A review of adverse pregnancy outcomes and formaldehyde exposure in human and animal studies

Ambient formaldehyde and mortality: A time series analysis in China

The potential health impact of low-level ambient formaldehyde has been historically overlooked. We conducted a two-stage time series analysis to investigate associations between ambient formaldehyde and daily nonaccidental, circulatory, and respiratory mortality and six subtypes based on 5,325,585 deaths in 275 Chinese counties between 2013 and 2018 and estimated a concentration-response curve to identify overall associations. After controlling for confounders from meteorological factors, air pollutants, time trend, and day of the week effect, with a 1-part per billion (ppb) increase in the daily concentration of formaldehyde on lag0 day, we found that mortality risks in nonaccidental, circulatory, and respiratory diseases increased by 0.36%, 0.36% and 0.41%, respectively. The curve indicated a possible threshold concentration at approximately 5 ppb for significant impact on nonaccidental and circulatory diseases. We suggest that ambient formaldehyde may represent a potential threat to public health and needs further investigation to support timely pollution regulation and health protection.

Association between maternal exposure to indoor air pollution and offspring congenital heart disease: a case–control study in East China

Background

Previous research suggested an association between maternal exposure to ambient air pollutants and the risk of congenital heart disease (CHD). However, the effect of individual prenatal exposure to indoor air pollutants on CHD occurrence was not reported.

Methods

We performed a hospital-based case–control study to investigate the association between personal air pollution exposure during pregnancy and the risk of CHD in offspring. A total of 44 cases and 75 controls were included from two hospitals in East China. We investigated maternal and residential environmental characteristics using a questionnaire and obtained personal indoor air samples to assess particulate matter (PM) and volatile organic compounds (VOCs) from 22–30 gestational weeks. Formaldehyde, benzene, toluene, xylene, total volatile organic compounds (TVOCs), PM_2.5, and PM₁₀ were assessed. Logistic regression was performed to assess associations and interactions between individual indoor air pollutants and CHD after adjusting for confounders. The potential residential environmental factors affecting the risks of indoor air pollutants on CHD were also assessed.

Results

Median TVOC (0.400 vs. 0.005 mg/m³, P < 0.001) exposure levels in cases were significantly higher than controls. A logistic regression model adjusted for confounders revealed that exposure to high levels of indoor TVOCs (AOR 7.09, 95% CI 2.10–23.88) during pregnancy was associated with risks for CHD and the occurrence of some major CHD subtype in offspring. These risk effects were enhanced in pregnant women living in a newly renovated house but were mitigated by household use of smoke ventilators when cooking. We observed a positive interaction of maternal exposure to TVOCs and PM_2.5 and the risk for CHD.

Conclusions

Maternal exposure to indoor VOCs and PMs may increase the risk of giving birth to foetuses with CHD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13174-0.

Highly efficient Ru/CeO2 catalysts for formaldehyde oxidation at low temperature and the mechanistic study

Ru species have a high redox capacity on a CeO₂ support, and the metallic Ru species could be easily oxidized back to RuO_x species.

Maternal occupational exposure to chemicals in the textile factory during pregnancy is associated with a higher risk of polydactyly in the offspring

Background: The number of children with polydactyly seen in our clinic is increasing. In addition to genetic factors, an influence of environmental effects during pregnancy is becoming increasingly apparent; however, epidemiological data on these effects are lacking.Methods: This hospital-based, case-control study enrolled 143 patients with polydactyly and 286 control patients with no genetic diseases, to evaluate the association between maternal exposure to a textile factory environment during pregnancy and the likelihood of giving birth to a child with polydactyly.Results: Maternal exposure to a textile factory environment during pregnancy was associated with an increased risk of giving birth to a child with polydactyly (exposure to textile factory environment: unadjusted odds ratio (OR) = 3.31, 95% confidence interval (CI) = 1.75-6.27, p = .0002; work seniority of exposed occupation: unadjusted OR 1.28, 95% CI = 1.13-1.47, p = .0002). Covariate screening indicated that certain risk factors (family monthly income per capita, mother's emotional state during pregnancy, colporrhagia, passive smoking, smoking, and history of consanguineous marriage) were potential confounding factors. After adjusting for these variables, the OR of exposure to a textile factory environment remained significant (exposure to textile factory environment: adjusted OR = 3.08, 95% CI = 1.32-7.19, p = .0094; work seniority of exposed occupation: adjusted OR = 1.58, 95% CI = 1.20-2.08, p = .0010). The risk of polydactyly increased with the number of years of employment.Conclusions: Maternal exposure to a textile factory environment appears to be a risk factor for polydactyly in newborns.

Effect of toxic ligands on O2 binding to heme and their toxicity mechanism

Heme, as the cofactor and active site of Hb, enables Hb to carry out the necessary function required for O2 management for life, that is, reversible O2 binding for transport. In this paper, the microscopic mechanism of heme-associated poisoning has been elucidated from the perspective of electronic interaction by performing first-principles calculations. The results show that the functional groups (-CHO, -COOH, -NO2, -NH2) and CN exhibit a stronger affinity for heme than O2 and are more likely to occupy the O2 binding site, which results in the loss of the ability of heme to carry O2. Moreover, the addition of functional groups, CO and CN to heme at the side site can cause a pronounced enhancement toward the O2 binding characteristics of heme, which prevents heme from releasing O2 to oxygen-consuming tissues as the blood circulates. The reversible O2 binding function of heme is disrupted by the presence of these toxic ligands in the heme binding pocket, which greatly affects O2 transport in the blood. The inability of tissues to obtain O2 leads to tissue hypoxia, which is the main cause of poisoning. Based on the energy, geometry and electronic properties, the hypoxia mechanism proposed by us coincides well with experiment, and the research has the potential to provide a theoretical reference for the relevant areas of bioscience.

Highly Efficient Polydopamine-coated Poly(methyl methacrylate) Nanofiber Supported Platinum⁻nickel Bimetallic Catalyst for Formaldehyde Oxidation at Room Temperature

We fabricated one fibrous-membrane type of flexible and lightweight supported catalyst via loading platinum–nickel nanoparticles (PtNi NPs) directly on the polydopamine-coated polymethylmethacrylate electrospun-fibers (PMMA@PDA). The polymer support with the PDA layer provided numerous active sites, leading to well-monodispersed and sized PtNi NPs on the nanofibers. Through the rational design of PtNi NPs, the resultant catalyst system exhibited 90% conversion for decomposing HCHO (10 ppm) at room temperature with only a low dosage (0.02 g), retaining the high activity for 100 h. This superior catalytic performance stems from the formate oxidation, which was the key intermediate during HCHO decomposition, and was promoted by the existence of a sufficient Pt–OH–Ni interface in the PtNi NPs with an appropriate Pt/Ni ratio of 1:5. Such tailored Pt-based nanoparticles ideally work together with the polymer nanofibers as a support for catalytic reaction. Compared with classical catalysts, our system can handle a comparable efficiency with much lower air resistance and remarkably lower dosage. Furthermore, the membrane-like morphology provides easy handling and minimizes the leaching of catalyst nanoparticles.

[Public Health in Colombian Zoos. A challenge for Veterinary Medicine]

This reflection aims to analyze the current status of public health management in zoos. In turn, it seeks to establish the importance of addressing this problem during the training and professional practice of veterinarians. The current situation of public health in Colombian zoos has weaknesses that are potentially correctable from both the academia and the daily practice of professionals directly or indirectly related. This becomes a challenge for educational institutions of related professions, zoos and veterinarians. Although some approximations have been made in this regard, information on this issue is still scarce.

MOF-derived metal oxide composite Mn2Co1Ox/CN for efficient formaldehyde oxidation at low temperature

A novel MOF-derived MnCoO_x nanoparticles embedded in porous N-doped carbon catalyst exhibits excellent catalytic activity for the low-temperature oxidation of formaldehyde.

Three-dimensional Mn–Cu–Ce ternary mixed oxide networks prepared by polymer-assisted deposition for HCHO catalytic oxidation

Mn–Cu–Ce ternary mixed oxide networks with a three-dimensional (3D) structure were developed by a polymer-assisted deposition method.

The effect of prenatal TVOC exposure on birth and infantile weight: the Mothers and Children's Environmental Health study

BACKGROUNDVolatile organic compounds (VOCs) might restrict prenatal and postnatal growth. However, the effect of the exposure of prenatal VOCs on postnatal growth has not been studied sufficiently. Thus, we investigated the relationship between the exposure of total volatile organic compounds (TVOCs) during pregnancy and its effects on postnatal growth.METHODSA total of 383 pregnant participants were enrolled from 2006 to 2008. We investigated maternal characteristics using a questionnaire. Personal air samples of TVOCs were obtained in mid or late pregnancy. After these mothers had given birth, 360 singleton newborns were selected and postnatal follow-up data were collected at 6, 12, 24, and 36 months, as well as anthropometric factors including body weight. Multiple general linear and mixed models were applied for statistical analyses.RESULTSThe mean concentration of prenatal exposure to TVOCs was 284.2 μg/m³ and that of formaldehyde was 81.6 μg/m³. The birth weight of newborns decreased significantly with prenatal TVOC exposure (β=-45.89, P=0.04). The adjusted mean body weight was 300 g lower in the high-TVOC group (⩾75th) compared with that in the low-exposure group (<75th).CONCLUSIONThese results indicate that elevated exposure to TVOCs during the prenatal period may adversely influence early postnatal growth.

[Occupational exposure to formaldehyde and new table of occupational diseases]

This paper presents an update on the carcinogenic effect of formaldehyde. First, generalities of its chemical composition are considered, followed by the description of some of its uses, both in the industry and in health institutions, as well as an account of the risk to which the general population is exposed, in particular health personnel, as a result of prolonged exposure to this chemical component. Emphasis is placed on the concentration of formaldehyde in everyday life and in the workplace, while the guidelines of decree 1477 of August 5, 2014, issued by the Ministry of Labor of Colombia, on occupational exposure to this chemical are analyzed to demonstrate that this decree does not consider the already known carcinogenic effects of formaldehyde, widely supported by scientific evidence, thus leaving a void for both occupational prevention and labor legislation.

Preparation of a Pt/TiO2/cotton fiber composite catalyst with low air resistance for efficient formaldehyde oxidation at room temperature

Pt/TiO₂/cotton fiber catalyst was successfully prepared with much lower air resistance than powder-like sample. It can catalyze oxidation of HCHO into CO₂ and H₂O with an optimum Pt loading of 0.75 wt%. It also exhibited good catalytic stability.

Effect of formaldehyde inhalation on Hsp70 in seminiferous tubules of rat testes: an immunohistochemical study

One parameter which might provide an insight into the underlying mechanism of the effect of formaldehyde (FA) inhalation on testicular tissue, is the assessment of heat shock protein 70 (Hsp70), which increases promptly in cells exposed to stress caused by chemical toxicity. Thus, following subchronic exposure at cytotoxic concentrations, we studied the immunohistochemical effect of FA inhalation on changes in Hsp70 content in testicular tissue.

We used 18 albino Wistar rats divided into three groups, exposed to 0 (control), 5 and 10 ppm FA gas for a total of 91 days, 8 h/day, five days a week. Serum testosterone levels were determined using a chemiluminescent enzyme immunoassay. Testicular tissues were stained with Hematoxylin-Eosine and Hsp70 immunohistochemically performed. Diameters of seminiferous tubules and serum testosterone levels in animals inhaling FA were significantly decreased. In seminiferous epithelium stained for Hsp70, compared to those in the control group, the spermatogenetic cells in the experimental groups demonstrated an obvious increase in immunoreaction spermatides in the adluminal region and especially in the cytoplasm of spermatocytes. Immunoreaction of Hsp70 was detected in the spermatogonias of animals exposed to FA inhalation as opposed to those of the control group. Compared to the control, there was a significant increase in the immunoreactions observed not only in the cytoplasm of primary spermatocytes, but also spermatides in the adluminal region of the seminiferous tubules.

In conclusion, FA gas may damage spermatogenetic cells and increase Hsp70 synthesis.

Room-temperature catalytic oxidation of formaldehyde on catalysts

Room-temperature catalytic oxidative decomposition of harmful formaldehyde (HCHO) in indoor air is summarized.

Flexible Mg–Al layered double hydroxide supported Pt on Al foil for use in room-temperature catalytic decomposition of formaldehyde

Flexible and bendable Mg–Al layered double hydroxide supported Pt catalysts fabricated and used in room-temperature catalytic decomposition of formaldehyde.

Formaldehyde Crosses the Human Placenta and Affects Human Trophoblast Differentiation and Hormonal Functions

The chorionic villus of the human placenta is the source of specific endocrine functions and nutrient exchanges. These activities are ensured by the syncytiotrophobast (ST), which bathes in maternal blood. The ST arises and regenerates throughout pregnancy by fusion of underlying cytotrophoblasts (CT). Any anomaly of ST formation or regeneration can affect pregnancy outcome and fetal growth. Because of its direct interaction with maternal blood, the ST is sensitive to drugs, pollutants and xenohormones. Ex vivo assays of perfused cotyledon show that formaldehyde, a common pollutant present in furniture, paint and plastics, can accumulate in the human placenta and cross to the fetal compartment. By means of RT-qPCR, immunoblot and immunocytochemistry experiments, we demonstrate in vitro that formaldehyde exerts endocrine toxicity on human trophoblasts, including a decrease in the production of protein hormones of pregnancy. In addition, formaldehyde exposure triggered human trophoblast fusion by upregulating syncitin-1 receptor expression (ASC-type amino-acid transporter 2: ASCT2). Moreover, we show that formaldehyde-exposed trophoblasts present an altered redox status associated with oxidative stress, and an increase in ASCT2 expression intended to compensate for this stress. Finally, we demonstrate that the adverse effects of formaldehyde on trophoblast differentiation and fusion are reversed by N-acetyl-L-cysteine (Nac), an antioxidant.

Hypercrosslinked porous polycarbazoles via one-step oxidative coupling reaction and Friedel–Crafts alkylation

Facile preparation of hypercrosslinked carbazole-based porous organic polymers via FeCl₃-promoted one-step oxidative coupling reaction and Friedel–Crafts alkylation from the vinyl or hydroxymethyl functionalized carbazole is reported.

An energy-efficient catalytic process for the tandem removal of formaldehyde and benzene by metal/HZSM-5 catalysts

A novel tandem temperature-pulse oxidation (TTPO) concept for energy-efficient catalytic removal of formaldehyde and benzene is proposed and realized over zeolite-hosted platinum catalysts.

Hierarchically macro-mesoporous flowerlike Pt/NiO composite microspheres for efficient formaldehyde oxidation at room temperature

A hierarchically macro-mesoporous flowerlike Pt/NiO catalyst shows more enhanced catalytic activity than a particle-like Pt/NiO catalyst.

Amended Safety Assessment of Formaldehyde and Methylene Glycol as Used in Cosmetics

Formaldehyde and methylene glycol may be used safely in cosmetics if established limits are not exceeded and are safe for use in nail hardeners in the present practices of use and concentration, which include instructions to avoid skin contact. In hair-smoothing products, however, in the present practices of use and concentration, formaldehyde and methylene glycol are unsafe. Methylene glycol is continuously converted to formaldehyde, and vice versa, even at equilibrium, which can be easily shifted by heating, drying, and other conditions to increase the amount of formaldehyde. This rapid, reversible formaldehyde/methylene glycol equilibrium is distinguished from the slow, irreversible release of formaldehyde resulting from the so-called formaldehyde releaser preservatives, which are not addressed in this safety assessment (formaldehyde releasers may continue to be safely used in cosmetics at the levels established in their individual Cosmetic Ingredient Review safety assessments).

Hierarchically macro-mesoporous Pt/γ-Al2O3 composite microspheres for efficient formaldehyde oxidation at room temperature

Room temperature catalytic oxidation by noble metals is considered to be the most promising strategy for the removal of HCHO, which is one of the major indoor air pollutants. Hierarchically macro-mesoporous structured Pt/γ-Al2O3 hollow spheres with open and accessible pores were synthesized and used for catalytic oxidative decomposition of HCHO at room temperature. The prepared composite hollow spheres showed higher catalytic activity than the conventional nanoparticle supports, which is mainly due to their hierarchical macro-mesoporous structure facilitating diffusion of reactants and products, and the high dispersion of accessible catalytic Pt nanoparticles. This work may contribute to the development of hierarchically structured materials and high-performance catalysts for indoor air purification and related catalytic processes.

Effects of adsorbed F, OH, and Cl ions on formaldehyde adsorption performance and mechanism of anatase TiO2 nanosheets with exposed {001} facets

Formaldehyde (HCHO), as the main indoor air pollutant, is highly needed to be removed by adsorption or catalytic oxidation from the indoor air. Herein, the F(-), OH(-), and Cl(-)-modified anatase TiO2 nanosheets (TNS) with exposed {001} facets were prepared by a simple hydrothermal and post-treatment method, and their HCHO adsorption performance and mechanism were investigated by the experimental analysis and theoretical simulations. Our results indicated that the adsorbed F(-), OH(-), and Cl(-) ions all could weaken the interaction between the HCHO and TNS surface, leading to the serious reduction of HCHO adsorption performance of TNS. However, different from F(-) and Cl(-) ions, OH(-) ion could induce the dissociative adsorption of HCHO by capturing one H atom from HCHO, resulting in the formation of one formyl group and one H2O-like group. This greatly reduced the total energy of the HCHO adsorption system. Thus, the adsorbed OH(-) ions could provide the additional active centers for HCHO adsorption. As a result, the NaOH-treated TNS showed the best HCHO adsorption performance mainly because its surface F(-) was replaced by OH(-). This study will provide new insight into the design and fabrication of high performance adsorbents for removing indoor HCHO and, also, will enhance the understanding of the HCHO adsorption mechanism.

The abatement of major pollutants in air and water by environmental catalysis

This review reports the research progress in the abatement of major pollutants in air and water by environmental catalysis. For air pollution control, the selective catalytic reduction of NO x (SCR) by ammonia and hydrocarbons on metal oxide and zeolite catalysts are reviewed and discussed, as is the removal of Hg from flue gas by catalysis. The oxidation of Volatile organic compounds (VOCs) by photo- and thermal-catalysis for indoor air quality improvement is reviewed. For wastewater treatment, the catalytic elimination of inorganic and organic pollutants in wastewater is presented. In addition, the mechanism for the procedure of abatement of air and water pollutants by catalysis is discussed in this review. Finally, a research orientation on environment catalysis for the treatment of air pollutants and wastewater is proposed.

Enhanced performance of NaOH-modified Pt/TiO2 toward room temperature selective oxidation of formaldehyde

Pt/TiO(2) catalysts with various Pt loadings (0.05-2 wt %) were prepared by a combined NaOH-assisted impregnation of titania with Pt precursor and NaBH(4)-reduction. The thermal catalytic activity was evaluated toward catalytic decomposition of formaldehyde (HCHO) vapor in the presence of toluene under ambient conditions. HCHO could be selectively oxidized into CO(2) and H(2)O over Pt/TiO(2) catalysts and toluene had no change. Pt/TiO(2) catalysts prepared with the assistance of NaOH showed higher HCHO oxidation activity than those without NaOH due to the introduction of additional surface hydroxyl groups, the enhanced adsorption capacity toward HCHO, and larger mesopores and macropores facilitating diffusion and transport of reactants and products. The as-prepared Pt/TiO(2) catalysts with an optimal Pt loading of 1 wt % exhibited high catalytic stability. Considering the versatile combination of noble-metal nanoparticles and supports, this work will provide new insights to the design of high-performance catalysts for indoor air purification.

Recent trend in risk assessment of formaldehyde exposures from indoor air

Studies about formaldehyde (FA) published since the guideline of 0.1 mg/m(3) by the World Health Organization (WHO) in 2010 have been evaluated; critical effects were eye and nasal (portal-of-entry) irritation. Also, it was considered to prevent long-term effects, including all types of cancer. The majority of the recent toxicokinetic studies showed no exposure-dependent FA-DNA adducts outside the portal-of-entry area and FA-DNA adducts at distant sites were due to endogenously generated FA. The no-observed-adverse-effect level for sensory irritation was 0.5 ppm and recently reconfirmed in hypo- and hypersensitive individuals. Investigation of the relationship between FA exposure and asthma or other airway effects in children showed no convincing association. In rats, repeated exposures showed no point mutation in the p53 and K-Ras genes at ≤15 ppm neither increased cell proliferation, histopathological changes and changes in gene expression at 0.7 ppm. Repeated controlled exposures (0.5 ppm with peaks at 1 ppm) did not increase micronucleus formation in human buccal cells or nasal tissue (0.7 ppm) or in vivo genotoxicity in peripheral blood lymphocytes (0.7 ppm), but higher occupational exposures were associated with genotoxicity in buccal cells and cultivated peripheral blood lymphocytes. It is still valid that exposures not inducing nasal squamous cell carcinoma in rats will not induce nasopharyngeal cancer or lymphohematopoietic malignancies in humans. Reproductive and developmental toxicity are not considered relevant in the absence of sensory irritation. In conclusion, the WHO guideline has been strengthened.

Effects of paternal occupation exposure to formaldehyde on reproductive outcomes

OBJECTIVE

To investigate whether paternal occupational exposure to formaldehyde (FA) affects the reproductive outcomes.

METHODS

Data were collected from 302 male workers occupationally exposed to FA and 305 referent controls through interview questionnaires. Formaldehyde exposure level was measured and calculated for every subject. Different reproductive outcomes were compared for two groups by logistic regression analyses.

RESULTS

A significant increased risk of prolonged time to pregnancy (P = 0.034; odds ratio, 2.828; 95% confidence interval, 1.081 to 7.406) and significant elevated risk of spontaneous abortion (P = 0.021; odds ratio, 1.916; 95% confidence interval, 1.103 to 3.329) were observed in wives of male workers occupationally exposed to FA after correction for confounding factors. Moreover, reproductive toxicity due to FA exposure is dose dependent.

CONCLUSIONS

This epidemiological study adds some evidence for the hypothesis that paternal FA occupation exposure has adverse effects on reproductive outcomes.

Histomorphological and ultrastructural changes of the placenta in mice exposed to formaldehyde

Formaldehyde (FA) is widely used in industrial and medical settings. It has long been suspected of causing adverse reproductive and developmental effects. However, the effects of exposure to FA on the reproduction are still a matter of scientific controversy. In this study, we evaluate the hypothesis that adverse developmental outcomes of the exposure to FA might be due to its effects on the placental structure. So, histological changes of the placenta in the mice exposed to FA gas were assessed at light and electron microscopy levels. A total of 40 pregnant Balb/C mice were randomly allotted to four groups in which the animals were exposed to FA at the doses of 0 (control), 7, 14 and 28 ppm, respectively, by inhalation, consecutively, for 8 h/d during the organogenesis period. On day 17 of gestation, the animals were killed and the histological specimens of the placentas were taken for light and electron microscopy studies. Also, morphological parameters of the placentas were measured manually. The results showed that the effects of FA on the placenta are not dose dependent. In the FA-exposed mice, an increase in the number and size of trophoblastic giant cells and an enlargement of spongiotrophoblastic cells in the basal zone of placenta were seen. Also, a significant increase in placental weight as well as the ratio of placental to fetal weight but a decrease in the fetal weight were found in the treated groups when compared with those in the control mice (p < 0.05). Moreover, ultrastructural results demonstrated that the diameter of labyrinth interhemal membrane as well as the thickness of trophoblastic basement membranes were significantly increased in the FA-exposed mice. In addition, in the FA-treated animals, a severe accumulation of cytoplasmic droplets in the II and III trophoblastic layers of the placenta were seen. In conclusion, this study may suggest that the exposure to FA during the organogenesis period at doses of 7-28 ppm induces toxic changes in the placental structure. These changes disrupt placental functions and leads to a decrease in the fetal weight.

Occupational exposures among nurses and risk of spontaneous abortion

OBJECTIVE

We investigated self-reported occupational exposure to antineoplastic drugs, anesthetic gases, antiviral drugs, sterilizing agents (disinfectants), and X-rays and the risk of spontaneous abortion in US nurses.

STUDY DESIGN

Pregnancy outcome and occupational exposures were collected retrospectively from 8461 participants of the Nurses' Health Study II. Of these, 7482 were eligible for analysis using logistic regression.

RESULTS

Participants reported 6707 live births, and 775 (10%) spontaneous abortions (<20 weeks). After adjusting for age, parity, shift work, and hours worked, antineoplastic drug exposure was associated with a 2-fold increased risk of spontaneous abortion, particularly with early spontaneous abortion before the 12th week, and 3.5-fold increased risk among nulliparous women. Exposure to sterilizing agents was associated with a 2-fold increased risk of late spontaneous abortion (12-20 weeks), but not with early spontaneous abortion.

CONCLUSION

This study suggests that certain occupational exposures common to nurses are related to risks of spontaneous abortion.

Effects of low-dose, long-term formaldehyde exposure on the structure and functions of the ovary in rats

Formaldehyde (FA) is a ubiquitous environmental pollutant. However, the effects of FA exposure on reproduction are still a matter of scientific controversy. In this study, we assessed the ovarian toxicity of long-term, low-dose FA exposure in rats and explored the potential oxidative stress mechanisms. A total of 30 Sprague-Dawley female rats were randomly allotted to three groups, in which rats were exposed to FA at a dose of 0 mg/m(3) (control), 0.5 mg/m(3) and 2.46 mg/m(3), respectively, by inhalation consecutively for 60 days. The results showed that the ovarian toxicity of FA is dose dependent. Ovarian structure and function in the group of rats exposed to 0.5 mg/m(3) FA showed no obvious difference when compared with those in the control group. However, the activity of superoxide dismutase was significantly decreased, whereas the level of malondialdehyde was significantly increased in ovaries of rats exposed to 2.46 mg/m(3) FA. Moreover, histopathological results demonstrated that the number and size of mature follicles significantly decreased, vascular congestion and interstitial edema in the ovaries of rats exposed to 2.46 mg/m(3) FA. In conclusion, this study may suggest that the FA level of 0.5 mg/m(3) can be considered as a safe level for FA exposure, but long-term FA exposure at a dose of 2.46 mg/m(3) has a harmful effect on ovary by inducing oxidative stress.

Reproductive and developmental toxicity of formaldehyde: a systematic review

Formaldehyde, the recently classified carcinogen and ubiquitous environmental contaminant, has long been suspected of causing adverse reproductive and developmental effects, but previous reviews were inconclusive, due in part, to limitations in the design of many of the human population studies. In the current review, we systematically evaluated evidence of an association between formaldehyde exposure and adverse reproductive and developmental effects, in human populations and in vivo animal studies, in the peer-reviewed literature. The mostly retrospective human studies provided evidence of an association of maternal exposure with adverse reproductive and developmental effects. Further assessment of this association by meta-analysis revealed an increased risk of spontaneous abortion (1.76, 95% CI 1.20-2.59, p=0.002) and of all adverse pregnancy outcomes combined (1.54, 95% CI 1.27-1.88, p<0.001), in formaldehyde-exposed women, although differential recall, selection bias, or confounding cannot be ruled out. Evaluation of the animal studies including all routes of exposure, doses and dosing regimens studied, suggested positive associations between formaldehyde exposure and reproductive toxicity, mostly in males. Potential mechanisms underlying formaldehyde-induced reproductive and developmental toxicities, including chromosome and DNA damage (genotoxicity), oxidative stress, altered level and/or function of enzymes, hormones and proteins, apoptosis, toxicogenomic and epigenomic effects (such as DNA methylation), were identified. To clarify these associations, well-designed molecular epidemiologic studies, that include quantitative exposure assessment and diminish confounding factors, should examine both reproductive and developmental outcomes associated with exposure in males and females. Together with mechanistic and animal studies, this will allow us to better understand the systemic effect of formaldehyde exposure.

Pregnant students in the gross anatomy laboratory: policies and practices at chiropractic colleges

Chiropractic and medical colleges have experienced a significant increase in the number of female applicants in recent years, a percentage of whom are pregnant or become pregnant following admission. It is therefore important to ask the question: How do institutions that educate future health care providers address the issue of pregnancy and the gross anatomy laboratory? A survey instrument was developed and pretested. IRB approval was obtained. The administrators charged with overseeing the policies and practices for the gross anatomy laboratory at each of the 16 chiropractic colleges in the USA were identified and contacted. An email containing a link to the Web based survey was sent to each, using SurveyMonkey. The survey response rate was 100%. A majority of colleges (69%) have a written policy regarding pregnancy and the gross laboratory. Of these, 36% allow pregnant students to take the laboratory if a waiver is signed, 18% do not allow them to take the laboratory, 18% allow them to take it without a waiver, and 27% have other policies. In cases where students do not take the gross laboratory while pregnant, 64% of colleges require them to take the laboratory after completion of their pregnancy, 27% require them to complete an alternative (dry) laboratory, and 9% have other policies. Considerable diversity exists in the way colleges address this issue. It is at present unknown whether pregnant students or their fetuses are at any risk from laboratory chemicals. Risk assessment research is needed before consistent policies can be developed.