Estimation of suspected estrogenic transformation products generated during preservative butylparaben chlorination using a simplified effect-based analysis approach

Estrogenic transformation products (TPs) generated after water chlorination can be considered as an environmental and health concern, since they can retain and even increase the estrogenicity of the parent compound, thus posing possible risks to drinking water safety. Identification of the estrogenic TPs generated from estrogenic precursor during water chlorination is important. Herein, butylparaben (BuP), which was widely used as preservative in food, pharmaceuticals and personal care products (PPCPs), was selected for research. A simplified effect-based analysis (EDA) approach was applied for the identification of estrogenic TPs generated during BuP chlorination. Despite the removal of BuP corresponds to the decrease of estrogenicity in chlorinated samples, an significant increase of estrogenicity was observed (at T = 30 min, presented an estrogenicity equivalent to 17β-estradiol). Chemical analysis of the estrogenic chlorinated samples that have been previously subjected to biological analysis (in vitro assays), in combination with the principal component analysis (PCA) evaluation, followed by validating the estrogenic potency of most relevant estrogenic TPs through an in silico approach (molecular dynamics simulations), identified that the halogenated TP3 (3,5-Dichloro-butylparaben) increased by 62.5 % and 61.8 % of the estrogenic activity of the parent compound in samples chlorinated with 30 min and 1 h, respectively being classified as a potentially estrogenic activity driver after BuP chlorination. This study provides a scientific basis for the more comprehensive assessment of the environmental and health risk associated with BuP chlorination, highlighting the necessity of identifying the unknown estrogenic TPs generateded from estrogenic precursors chlorination.

Prenatal endocrine-disrupting chemicals exposure and impact on offspring neurodevelopment: A systematic review and meta-analysis

PURPOSE

Considering that endocrine disruptors have certain effects on fetal growth, we conducted a systematic review of epidemiological literature to elucidate the correlation between exposure to endocrine-disrupting chemicals during pregnancy and the neurodevelopment of offspring.

METHOD

We systematically explored PubMed, Web of Science, and CINAHL databases from inception to April 4, 2023. References from pertinent studies were reviewed, and data regarding the link between maternal prenatal EDC exposure and offspring neurological development were compiled. A domain-based approach was used to evaluate studies of neurodevelopmental effects in children ≤3 years old by two reviewers, including cognition, motor, behavior, language, and non-verbal ability.

RESULTS

A comprehensive search yielded 45,373 articles, from which 48 articles, involving 26,005 mother-child pairs, met the criteria and were subsequently included in our analysis. The results revealed that EDC exposure during pregnancy had a significant impact on offspring neurobehavior development, especially in cognition, motor, and language. Our findings indicated adverse associations between prenatal exposure to metals and offspring cognition (before 12 months: β coefficient: -0.28; 95 % CI, -0.50 to -0.06; 1-3 years old: β coefficient: -0.55; 95 % CI: -1.08 to -0.02). Furthermore, metals (β coefficient: -0.71; 95 % CI: -1.23 to -0.19) and phthalates (β coefficient: -0.69; 95 % CI: -1.05 to -0.33) exposure exhibited detrimental effects on motor development from1-3 years old, while poly-fluoroalkyl substances were linked to the disruption of offspring language development (β coefficient: -1.01; 95 % CI: -1.90 to -0.11) within this timeframe. Additionally, exposure to EDCs during pregnancy had a negative impact on cognition development among girls from 12 to 36 months of age (β coefficient: -0.53; 95 % CI: -1.01 to -0.06).

CONCLUSION

Prenatal exposure to EDCs, especially metals, phthalates and, poly-fluoroalkyl substances, was associated with disrupting the development of offspring neurobehavior in the short and long term. Additionally, cognitive development showed gender differences due to prenatal endocrine-disrupting chemicals exposure.

Repeated-dose toxicity and toxicokinetic study of isobutylparaben in rats subcutaneously treated for 13 weeks

Parabens have historically served as antimicrobial preservatives in a range of consumables such as food, beverages, medications, and personal care products due to their broad-spectrum antibacterial and antifungal properties. Traditionally, these compounds were believed to exhibit low toxicity, causing minimal irritation, and possessing limited sensitization potential. However, recent evidence suggests that parabens might function as endocrine-disrupting chemicals (EDCs). Consequently, extensive research is underway to elucidate potential human health implications arising from exposure to these substances. Among these parabens, particular concerns have been raised regarding the potential adverse effects of iso-butylparaben (IBP). Studies have specifically highlighted its potential for inducing hormonal disruption, significant ocular damage, and allergic skin reactions. This study aimed to evaluate the prolonged systemic toxicity, semen quality, and estrus cycle in relation to endocrine disruption endpoints, alongside assessing the toxicokinetic behavior of IBP in Sprague-Dawley rats following a 13-week repeated subcutaneous administration. The rats were administered either the vehicle (4% Tween 80) or IBP at dosage levels of 2, 10, and 50 mg/kg/day for 13 weeks. Blood collection for toxicokinetic study was conducted on three specified days: day 1 (1st), day 30 (2nd), and day 91 (3rd). Systemic toxicity assessment and potential endocrine effects were based on various parameters including mortality rates, clinical signs, body weights, food and water consumption, ophthalmological findings, urinalysis, hematological and clinical biochemistry tests, organ weights, necropsy and histopathological findings, estrus cycle regularity, semen quality, and toxicokinetic behavior. The findings revealed that IBP induced local irritation at the injection site in males at doses ≥ 10 mg/kg/day and in females at 50 mg/kg/day; however, systemic toxicity was not observed. Consequently, the no-observed-adverse-effect level (NOAEL) for IBP was determined to be 50 mg/kg/day in rats of both sexes, indicating no impact on the endocrine system. The toxicokinetics of IBP exhibited dose-dependent systemic exposure, reaching a maximum dose of 50 mg/kg/day, and repeated administration over 13 weeks showed no signs of accumulation.

A pilot study of several environmental endocrine disrupting chemicals in children with autism spectrum disorder in south China

Autism spectrum disorders (ASD) is a group of heterogeneous neurodevelopmental disorders. Evidence has implied that environmental pollutants are important factors related to ASD. In this study, several environmental endocrine-disrupting chemicals, including parabens, benzophenone-type ultraviolet filters, hydroxyl polycyclic aromatic hydrocarbons, triclosan and tetrabromobisphenol A were analyzed in blood plasma in ASD children (n = 34) and the control children (n = 28). The results showed that parabens were the most concentrated chemicals (2.18 ng/mL, median value), followed by hydroxyl polycyclic aromatic hydrocarbons (0.73 ng/mL), benzophenone-type ultraviolet filters (0.14 ng/mL), triclosan (0.13 ng/mL) and tetrabromobisphenol A (0.03 ng/mL). ASD children accumulated significantly lower 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 4-hydroxybenzophenone and triclosan but higher 2-hydroxyphenanthrene and tetrabromobisphenol A than the control children (0.02/0.09 ng/mL of 2-hydroxy-4-methoxybenzophenone, p < 0.05; 0.04/0.07 ng/mL of 2,4-dihydroxybenzophenone, p < 0.05; 0.03/0.04 ng/mL of 4-hydroxybenzophenone, p < 0.05; 0.13/1.22 ng/mL of triclosan, p < 0.01; 0.03 ng/mL/not detected of 2-hydroxyphenanthrene, p < 0.05; 0.03/0.004 ng/mL of tetrabromobisphenol A, p < 0.05). Gender differences in certain environmental endocrine-disrupting chemicals were evident, and the differences were more inclined toward boys. Positive associations between 2-hydroxy-4-methoxybenzophenone and triclosan, and tetrabromobisphenol A and 2-hydroxyphenanthrene were found in ASD boys. Binary logistic regression analysis showed that the adjusted odds ratio value of 2-hydroxyphenanthrene in ASD boys was 11.0 (1.45-84.0, p < 0.05). This is the first pilot study on multiple environmental endocrine-disrupting chemicals in children with ASD in China.

Parabens as chemicals of emerging concern in the environment and humans: A review

Parabens are one of the most widely used preservatives in food, pharmaceuticals and personal care products (PCPs) because of their advantageous properties and low toxicity based on the early assessments. However, recent research indicates that parabens may act as endocrine-disrupting chemicals (EDCs) and thus, are considered as chemicals of emerging concern that have adverse human health effects. To provide the basis for future human health studies, we reviewed relevant literature, published between 2005 and 2020, regarding the levels of parabens in the consumer products (pharmaceuticals, PCPs and food), environmental matrices and humans, including susceptible populations, such as pregnant women and children. The analysis showed that paraben detection rates in consumer products, environmental compartments and human populations are high, while the levels vary greatly by country and paraben type. The concentrations of parabens reported in pregnant women (~20-120 μg/L) were an order of magnitude higher than in the general population. Paraben concentrations in food and pharmaceuticals were at the ng/g level, while the levels in PCPs reached mg/g levels. Environmental concentrations ranged from ng/L-μg/L in surface waters to tens of μg/g in wastewater and indoor dust. The levels of human exposure to parabens appear to be higher in the U.S. and EU countries than in China and India, which may change with the increasing production of parabens in the latter countries. The review provides context for future studies to connect paraben exposure levels with human health effects.

Association of placental concentrations of phenolic endocrine disrupting chemicals with cognitive functioning in preschool children from the Environment and Childhood (INMA) Project

Developmental exposure to bisphenol A (BPA) and other phenolic endocrine disrupting chemicals (EDCs) may affect child neurodevelopment, but data on the effects of prenatal exposure to phenols on cognitive function remain sparse. Our aim was to examine the association of placental concentrations of several phenolic EDCs, including BPA, parabens (PBs), and benzophenones (BzPs), with cognitive development in preschool children from the Environment and Childhood (INMA) Project in Spain. Concentrations of BPA, four PBs (methylparaben [MePB], ethylparaben [EtPB], propylparaben [PrPB], and butylparaben [BuPB]), and six BzPs (BzP-1, BzP-2, BzP-3, BzP-6, BzP-8, and 4-hydroxybenzophenone [4-OH-BzP]) were measured in 490 placenta samples randomly selected from five INMA cohorts collected between 2000 and 2008. Neuropsychological assessment of cognitive and motor function was performed with the McCarthy Scales of Children's Abilities (MSCA) at the age of 4-5 years. Associations were assessed in a sub-sample of 191 mother-child pairs using linear and logistic regression models adjusted for confounding factors. PB compounds were detected in more than 71% of placentas, BPA in 62%, 4-OH-BzP in 50%, and the remaining BzPs in <9% of the samples. Because of the low detection frequency of BzP compounds, only 4-OH-BzP was included in the exposure-outcome analyses. After adjustment for confounders, BPA was associated with greater odds of scoring lower (below the 20th percentile) in the verbal (third vs. first exposure tertile: odds ratio [OR] = 2.78, 95% confidence interval [CI] = 1.00; 5.81, p-trend = 0.05) and gross motor (detected vs. undetected: OR = 1.75, 95%CI = 1.06; 9.29) areas, and these associations were only significant for boys. Regarding PB compounds, PrPB was associated with lower scores in memory (detected vs. undetected: β = -4.96, 95%CI = -9.54; -0.31), span memory (OR = 2.50, 95%CI = 0.95; 6.92 and 2.71, 95%CI = 0.97; 6.64, respectively for second and third tertiles, p-trend = 0.03), and motor function (β = -5.15, 95%CI = -9.26; -0.01 for third vs. first exposure tertile, p-trend = 0.04). EtPB and total PBs concentrations in the second tertile were also associated with poorer visual function of posterior cortex and worse quantitative performance, respectively, but linear trends were not statistically significant. The associations of BPA and PrPB with poorer verbal, memory, and motor skills are novel observations that warrant further attention. Larger prospective studies are required to confirm whether prenatal exposure to BPA and other phenolic EDCs is associated with impaired cognitive development.

Methylparaben in meconium and risk of maternal thyroid dysfunction, adverse birth outcomes, and Attention-Deficit Hyperactivity Disorder (ADHD)

BACKGROUND

Parabens, which are used as a preservative in foods and personal care products, are detected in nearly 100% of human urine samples. Exposure to parabens is associated with DNA damage, male infertility, and endocrine disruption in adults, but the effects of prenatal exposure are unclear. In part, this is due to inadequate assessment of exposure in maternal urine, which may only reflect maternal rather than fetal exposure. To address this gap, we examined the association of prenatal methylparaben measured in meconium with preterm birth, gestational age, birthweight, maternal thyroid hormones, and child Attention-Deficit Hyperactivity Disorder (ADHD) at 6-7 years.

DESIGN

Data come from the GESTation and the Environment (GESTE) prospective observational pregnancy cohort in Sherbrooke, Quebec, Canada. Participants were 345 children with data on ADHD among 394 eligible pregnancies in women age ≥18 years with no known thyroid disease before pregnancy and meconium collected at delivery. Methylparaben was measured in meconium. Birthweight, gestational age, and maternal thyroid hormones at <20 weeks gestation were measured at the Centre Hospitalier Universitaire de Sherbrooke. Preterm birth was defined as vaginal birth before the 37th week of gestation. Physician diagnosis of ADHD was determined at a scheduled cohort follow-up when children were 6-7 years old or from medical records. Associations between meconium methylparaben and outcomes were estimated with logistic and linear regressions weighted on the inverse probability of exposure to account for potential confounders, including child sex, familial income, maternal education, pre-pregnancy body mass index, age, and smoking and alcohol consumption during pregnancy.

RESULTS

Methylparaben was detected in 65 meconium samples (19%), 33 children were diagnosed with ADHD (10%), and 13 children were born preterm (4%). Meconium methylparaben was associated with preterm birth (odds ratio [OR] = 4.81; 95% CI [2.29, 10.10]), decreased gestational age (beta [β] = -0.61 weeks; 95% CI [-0.93, -0.29]) and birthweight (β = -0.12 kg; 95% CI [-0.21, -0.03]), altered maternal TSH (relative concentration [RC] = 0.76; 95% CI [0.58, 0.99]), total T3 (RC = 0.84; 95% CI [0.75, 0.96]) and total T4 (RC = 1.10; 95% CI [1.01, 1.19]), maternal hypothyroxinemia (OR = 2.50, 95% CI [1.01, 6.22]), and child ADHD at age of 6-7 (OR = 2.33, 95% CI [1.45, 3.76]). The effect of meconium methylparaben on ADHD was partially mediated by preterm birth (20% mediation) and birthweight (13% mediation).

CONCLUSIONS

Meconium methylparaben was associated with preterm birth, decreased gestational age and birthweight, maternal thyroid hormone dysfunction, and child ADHD. Parabens are a substantial health concern if causally related to these adverse outcomes.

Parental preconception and prenatal urinary bisphenol A and paraben concentrations and child behavior

Epidemiologic studies suggest that prenatal urinary bisphenol A (BPA) concentrations are associated with childhood behavior problems, but there is limited research on prenatal paraben concentrations. In rodent offspring, preconception maternal BPA exposure caused behavioral problems and paraben exposure impacted sperm quality. However, the effects of parental preconception and prenatal BPA and paraben exposure on children's neurodevelopment are unknown.

METHODS

The Environment and Reproductive Health (EARTH) Study is a prospective cohort of couples from a fertility clinic at Massachusetts General Hospital. The Centers for Disease Control and Prevention (CDC) quantified BPA, butylparaben, ethylparaben, methylparaben, and propylparaben concentrations in multiple urine samples collected before conception and during pregnancy. From the eligible parents (N = 220), we enrolled 158 children between 2 and 9 years of age. The parents completed the Behavior-Assessment-System-for-Children-2 (BASC-2). We estimated covariate-adjusted associations of average parental preconception and prenatal ln-transformed urinary BPA and sum of paraben concentrations (∑paraben) with BASC-2 scores using linear regression with generalized estimating equations.

RESULTS

Median urinary BPA and Σparaben concentrations were 1.2 and 189 μg/L in mothers preconception and 1.7 and 25 μg/L in fathers preconception, respectively. Among all children, parental BPA and ∑paraben concentrations were not associated with BASC-2 behavioral symptoms index, internalizing, or externalizing problems scores. Point estimates ranged from -1.5 to 1.4 with wide 95% confidence intervals that included the null value.

CONCLUSION

In this fertility clinic cohort, parental preconception and maternal prenatal BPA and paraben concentrations were not associated with problem behaviors among children. However, our small sample sizes reduced the precision of our results.

Prenatal exposure to benzophenones, parabens and triclosan and neurocognitive development at 2 years

BACKGROUND

Benzophenones (BPs), parabens, and triclosan (TCS) are widely used in personal care products and may be neurotoxic to children, but limited studies have estimated the associations between exposure to these potential endocrine disrupting chemicals during pregnancy and child neurocognitive development.

OBJECTIVE

Our aim was to evaluate the relationships of prenatal exposure to BPs, parabens and TCS with child neurocognitive development at age 2.

METHODS

From 2014 to 2015, 478 mother-child pairs from a longitudinal prenatal cohort in China were included in present study. We quantified BPs, parabens and TCS in three spot urine samples during pregnancy (in the first, second, and third trimester). The Bayley Scales of Infant Development (BSID) test to children was performed at 2 years. Multivariate linear regression models and generalized estimating equations were used to examine changes in mental developmental index (MDI) and psychomotor development index (PDI) per 2-fold increase in averaged and trimester-specific maternal urinary phenols, respectively.

RESULTS

In the adjusted models, each 2-fold increase in average prenatal paraben concentration was associated with lower MDI scores among girls [-1.08 (95% CI: -2.10, -0.06) and - 1.51 (95% CI: -2.69, -0.32) for methyl paraben (Mep) and Σparabens, respectively], but the association was not statistically significant among boys [-0.24 (95% CI: -1.46, 0.99), P_sex-int = 0.37 and 0.18 (95% CI: -1.28, 1.64), P_sex-int = 0.10 for Mep and Σparabens, respectively]. Increasing urinary 4-hydroxybenzophenone (4-OH-BP) concentration was associated with lower PDI scores among boys [-2.96 (95% CI: -4.48, -1.45)], not girls [-0.07 (95% CI: -1.57, 1.43)] and the association was significantly different in boys and girls (P_sex-int = 0.01). No significant associations were observed between the average prenatal TCS exposure and BSID results. In trimester-specific analyses, increasing parabens was associated with lower girls' MDI only in the second trimester, while increasing 4-OH-BP was associated with lower boys' PDI in each trimester.

CONCLUSION

Our results suggest that prenatal exposure to BPs and parabens may be associated with impairment in child cognitive abilities at 2 years. Further human and animal studies are needed to verify our results and elucidate the biological mechanisms involved in these associations.

Repeated Measurements of Paraben Exposure during Pregnancy in Relation to Fetal and Early Childhood Growth

Parabens are potential endocrine disruptors with short half-lives in the human body. To date, few epidemiological studies regarding repeated paraben measurements during pregnancy associated with fetal and childhood growth have been conducted. Within a Chinese prenatal cohort, 850 mother-infant pairs from whom a complete set of maternal urine samples were acquired during three trimesters were included, and the levels of five parabens were measured. We assessed the associations of both average and trimester-specific urinary paraben levels with weight and height z-scores at birth, 6 months, 1, and 2 years of age. In all infants, each doubling increase in average ethyl paraben (EtP) was associated with -2.82% (95% CI: -5.11%, -0.53%) decrease in weight z-score at birth, whereas no significant age-specific associations were identified. After stratifying by sex, we further observed age-specific association of average EtP with -3.96% (95% CI: -7.03%, -0.89%) and -3.38% (95% CI: 6.72%, -0.03%) reduction in weight z-scores at 1 and 2 years in males, respectively. Third-trimester EtP was negatively associated with weight z-scores at birth, 1 and 2 years in males. Our results suggested negative associations between prenatal paraben exposure and fetal and childhood growth, and the third trimester may be the window of susceptibility.

Parabens and their effects on the endocrine system

Preservatives (ingredients which inhibit growth of microorganisms) are used to prolong shelf life of various foods, cosmetics, and pharmaceutical products. Parabens are one of the most popular preservatives used in the aforementioned products and is currently being used worldwide. Parabens are easily absorbed by the human body. Thus, it is important to discuss about their safety with respect to human physiology. In view of the current literature, which classifies parabens as a group of endocrine disrupting chemicals (EDCs), it seems that the precise assessment of their influence on the human endocrine system is particularly important. Disruption of the endocrine homoeostasis might lead to multidirectional implications causing disruption of fitness and functions of the body. Therefore, in this review article, we aimed to summarize the current literature on properties, occurrence, and metabolism of parabens as well as to present recent progress in knowledge about their influence on the human endocrine system.

Long-term effects of in utero and lactational exposure to butyl paraben in female rats

Parabens are used as preservatives in cosmetic, pharmaceutical, and food industries, and are frequently detected as contaminants in human fluids and tissues. The endocrine disrupting effects of parabens in female rodents include uterotrophic response, steroidogenesis impairment, and ovarian disturbances. The objective of this study was to determine the effects of maternal butyl paraben (BP) exposure on female sexual development. Pregnant Wistar rats were treated subcutaneously with either corn oil or BP at doses of 10, 100, or 200 mg/kg, from gestational day (GD) 12 until GD 20 for female foetal gonad evaluation, and from GD 12 until the end of lactation to evaluate sexual parameters on the female offspring. Immature female rats were also used in the uterotrophic assay to evaluate the possible estrogenic action of parabens. Our results revealed that, in this experimental protocol, BP did not show estrogenic activity at the doses used and did not impair sexual development and fertility capacity in the female rats, but impaired sexual behavior. We conclude that brain sexual development may be more sensitive to BP effects and we speculate that doses higher than 100 mg/kg (the male lowest observed adverse effect level (LOAEL) for rodent reproductive parameters) would be necessary to promote damages in the female reproduction, regarding the same protocol of exposure. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 776-788, 2017.

A Single Neonatal Injection of Ethinyl Estradiol Impairs Passive Avoidance Learning and Reduces Expression of Estrogen Receptor α in the Hippocampus and Cortex of Adult Female Rats

Although perinatal exposure of female rats to estrogenic compounds produces irreversible changes in brain function, it is still unclear how the amount and timing of exposure to those substances affect learning function, or if exposure alters estrogen receptor α (ERα) expression in the hippocampus and cortex. In adult female rats, we investigated the effects of neonatal exposure to a model estrogenic compound, ethinyl estradiol (EE), on passive avoidance learning and ERα expression. Female Wistar-Imamichi rats were subcutaneously injected with oil, 0.02 mg/kg EE, 2 mg/kg EE, or 20 mg/kg 17β-estradiol within 24 h after birth. All females were tested for passive avoidance learning at the age of 6 weeks. Neonatal 0.02 mg/kg EE administration significantly disrupted passive avoidance compared with oil treatment in gonadally intact females. In a second experiment, another set of experimental females, treated as described above, was ovariectomized under pentobarbital anesthesia at 10 weeks of age. At 15-17 weeks of age, half of each group received a subcutaneous injection of 5 μg estradiol benzoate a day before the passive avoidance learning test. Passive avoidance learning behavior was impaired by the 0.02 mg/kg EE dose, but notably only in the estradiol benzoate-injected group. At 17-19 weeks of age, hippocampal and cortical samples were collected from rats with or without the 5 μg estradiol benzoate injection, and western blots used to determine ERα expression. A significant decrease in ERα expression was observed in the hippocampus of the estradiol-injected, neonatal EE-treated females. The results demonstrated that exposure to EE immediately after birth decreased learning ability in adult female rats, and that this may be at least partly mediated by the decreased expression of ERα in the hippocampus.

Assessment of effects of mifepristone administration to lactating mice on the development and fertility of their progeny

AIM

Mifepristone, a synthetic steroid compound that induces abortion, was recently found to potentially pass into human milk. This study aimed to determine the effects of mifepristone administration to lactating mice on the development and reproduction of their progeny.

METHODS

Lactating mice were gavage fed with mifepristone (8 mg/kg) daily for 4 days either from days 1-4 or from days 7-10 of lactation; controls received only peanut oil. Growth, mortality rate, organ weight to bodyweight ratio, sex hormone at 20, 40 and 60 days, fertility of these F1 progeny and litter size, sex ratio and mortality rate of the second generation were recorded.

RESULTS

No significant differences were observed in the average bodyweight, mortality rate of the female or male pups, and organ coefficient of uterus and ovaries of females in adulthood in comparison with the controls. However, the organ coefficient of testis at day 20 and 40 and testosterone concentration at day 60 were increased in male pups. Moreover, the reproductive capacity of the F1 pups was unaffected by 4 days exposure to mifepristone via their mother's milk: time to birth of F2 pups, litter size, sex ratio and mortality rate were similar to control F1 pups.

CONCLUSION

The study showed that treating lactating mice with 8 mg/kg mifepristone influenced only the organ coefficient of testis at day 40 and the testosterone concentration in male pups at day 60, however, it did not affect the development and fertility of female and male pups.

Parabens: potential impact of low-affinity estrogen receptor binding chemicals on human health

Parabens, alkyl esters of p-hydroxybenzoic acid, are widely used in cosmetics, pharmaceuticals, personal care products and as food additives to inhibit microbial growth and extend product shelf life. Consumers of these compounds are frequently exposed via the skin, lips, eyes, oral mucosa, nails, and hair. Parabens are estrogenic molecules but exert weaker activity than natural estrogens, which would imply a low risk. Consistent with this idea, a number of recent commission reports from different countries suggested that parabens pose a negligible endocrine-disrupting risk at the recommended doses. However, individuals are not routinely exposed to a single paraben, and most of the available paraben toxicity data, reviewed in these reports, are from single-exposure studies. Further, assessing the additive and cumulative risk of multiple paraben exposure from daily use of multiple cosmetic and/or personal care products is presently not possible based on current studies. In this review, current and recent studies of paraben exposure and public health policies as well as critical gaps in the knowledge are discussed and new research directions regarding multiple exposures and novel target cohorts are recommended.