Para-dichlorobenzene toxicity - a review of potential neurotoxic manifestations

Do mould inhibitors alter the microbial community structure and antibiotic resistance gene profiles on textiles?

Mould inhibitors are closely associated with human health and have been extensively applied to textiles to prevent mould and insect infestations. However, the impact of these mould inhibitors on the microbial community structure on textiles and antibiotic resistance gene (ARG) profiles remains largely unexplored. In this study, testing techniques, including high-throughput quantitative PCR and Illumina sequencing, were employed to analyse the effects of three types of mould inhibitors -para-dichlorobenzene (PDCB), naphthalene, and natural camphor balls-on the composition of microbial communities and ARG profiles. The microbial mechanisms underlying these effects were also investigated. The experiments revealed that PDCB reduced the diversity of bacterial communities on textiles, whereas naphthalene and natural camphor balls exerted relatively minor effects. In contrast with bacterial diversity, PDCB enhanced the diversity of fungal communities on textiles, but significantly reduced their abundance. Naphthalene had the least impact on fungal communities; however, it notably increased the relative abundance of Basidiomycota. All three types of mould inhibitors substantially altered ARG profiles. Potential mechanisms responsible for the alterations in ARG profiles include microbial community succession and horizontal gene transfer mediated by mobile genetic elements. PDCB prominently increased the abundance of ARGs, mainly attributable to the relative enrichment of potential hosts (including certain γ-Proteobacteria and Bacillales) for specific ARGs. Thus, this study has important implications for the selection of mould inhibitors, as well as the assessment of microbial safety in textiles.

Associations of dichlorophenol with metabolic syndrome based on multivariate-adjusted logistic regression: a U.S. nationwide population-based study 2003-2016

BACKGROUND

Para-dichlorobenzene (p-DCB) exposure associated with oxidative stress has indeed raised public concerns. However, whether p-DCB is linked with metabolic syndrome (MetS) remains unclear. We hypothesized that higher exposure to p-DCB would be linked with a higher risk of MetS in the U.S population. This study aimed to examine the associations of exposure to p-DCB with MetS prevalence.

METHODS

We included 10,428 participants (5,084 men and 5,344 women), aged ≥ 20 years, from the National Health and Nutrition Examination Survey (2003-2016). The cases of MetS were diagnosed by NCEP/ATPIII. Logistic regression models were conducted to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of MetS prevalence. Moreover, the mix associations of p-DCB metabolites were assessed using quantile sum (WQS) regression and quantile g-computation (qgcomp) methods.

RESULTS

We documented 2,861 (27.1%) MetS cases. After adjustment for the potential risk factors, the ORs (95% CI) of MetS prevalence across the quartile of urinary 2,5-dichlorophenol (2,5-DCP) were 1.09 (0.93-1.28), 1.22 (1.00-1.49), and 1.34 (1.04-1.73). Moreover, 2,5 DCP is significantly associated with a higher prevalence of abdominal obesity [ORQ4vsQ1 (95% CI): 1.23 (1.03-1.48)]. The WQS and qgcomp index also showed significant associations between p-DCB metabolites and MetS. Moreover, we further examined that 2,5 DCP was correlated with higher systolic blood pressure (r = 0.022, P = 0.027), waist circumference (r = 0.099, P < 0.001), and glycohemoglobin (r = 0.027, P = 0.008) and a lower high density cholesterol (r = -0.059, P < 0.001). In addition, the significant positive associations between 2,5 DCP and MetS were robust in the subgroup and sensitivity analyses.

CONCLUSION

These findings indicated that increased urinary p-DCB concentration, especially 2,5 DCP, had a higher MetS prevalence. These results should be interpreted cautiously and further research is warranted to validate our findings.

Rare case of chronic naphthalene ball ingestion in a young Indian woman

Chronic oral abuse of naphthalene balls is extremely rare. It is associated with different types of metabolic toxicity, neurological deficits and multiple organ failure. However, the psychological implication of naphthalene abuse is poorly understood. This is a unique case report of a 29-year-old lady who presented with a 17 year history of naphthalene ball consumption. Historically, there have been self-harm behaviors, fire setting, cleaning compulsions, and involuntary motor movements associated with naphthalene. A series of assessments were conducted to assess her personality, psychiatric symptoms and cognitive functions. Additionally, blood tests, CT scan and MRI were done. The patient's profile indicated no apparent medical, neurological or cognitive impairments. Her psychological profile revealed significant co-morbidities and marked personality pathology. The case study provides useful insights into the presentation of chronic naphthalene ball ingestion in an Indian woman, thereby indicating the need to identify psychosocial and biological markers longitudinally. It also highlights recognition of common household items that can be abused, suggesting better understanding of protecting vulnerable individuals from the same.

Exposure to p-dichlorobenzene and prevalent endocrine-related reproductive cancers among US women

P-dichlorobenzene (p-DCB) is a pest repellent and air deodorant that is commonly found in the household and public buildings. Exposure to p-DCB has been suggested to have potential metabolic and endocrine effects. Little is known about its association with endocrine-related female cancers. In this cross-sectional study, a nationally representative subsample of 4459 women, aged 20 years or older, in the 2003-2016 National Health and Nutrition Examination Survey was analyzed for the association between p-DCB exposure, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the primary metabolite of p-DCB, and prevalent endocrine-related female cancers (defined as breast, ovarian, and uterine cancers) using multivariate logistic regression models, adjusting for potential confounders. Of the study participants, 202 women (weighted prevalence, 4.20%) reported being diagnosed with any of these endocrine-related reproductive cancers. Women with reproductive cancers showed a statistically significant increase in urinary 2,5-DCP concentrations (weighted geometric mean, 7.97 vs. 5.84 µg/g creatinine; p < 0.0001), compared to women without these cancers. After adjusting for potential confounders, we found that women in the moderate (1.94- < 28.10 µg/g creatinine) and high level (≥ 28.10 µg/g creatinine) of 2,5-DCP had significantly increased odds of endocrine-related reproductive cancers (odds ratio of 1.66 (95% CI: 1.02, 2.71) and 1.89 (1.08, 3.29), respectively), as compared with those in the low exposure group (< 1.94 µg/g creatinine). This study demonstrates a potential relation between p-DCB exposure and prevalent endocrine-related reproductive cancers in US women. Prospective and mechanistic studies would further explore these interactions and elucidate the pathogenesis of endocrine-related female cancers potentially associated with p-DCB exposure.

Exposure to p-dichlorobenzene and serum α-Klotho levels among US participants in their middle and late adulthood

P-dichlorobenzene (p-DCB) is a volatile compound commonly used as pest repellent and air deodorant in the home and public buildings, leading to a widespread exposure in indoor environments. There has been an increasing concern about its metabolic and endocrine effects. In this study, we explored the relation between p-DCB exposure and serum levels of soluble α-Klotho, an anti-aging hormone, in US adults. A nationally representative subsample of 1485 adults 40-79 ages in the 2013-2016 National Health and Nutrition Examination Survey was analyzed for the association between p-DCB exposure, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the major metabolite of p-DCB, and serum α-Klotho levels using multiple general linear models, adjusting for potential confounders. Age- and sex-specific analyses were further conducted. The weighted geometric mean of urinary 2,5-DCP was 2.43 μg/L and the weighted mean of serum α-Klotho was 831.97 pg/mL in the study participants during 2013-2016. After adjusting for potential confounders and urinary creatinine, urinary 2,5-DCP was significantly associated with decreased serum levels of α-Klotho (regression coefficient β = -9.88; p = 0.0133) in the total study population. When age- and sex-specific analyses being conducted, a significantly inverse association was found in older adults aged 60-79 years (β = -20.40; p = 0.0001) and in males (β = -13.81; p = 0.0097), but not in the middle ages (40-59 years) and in females. The strongest association was observed in older (60-79 years) male participants, with a 25.43 pg/mL reduction of α-Klotho levels per 1-unit increase of 2,5-DCP concentrations (p = 0.0008). This is the first study demonstrating a relation between p-DCB exposure, measured as 2,5-DCP, and decreased α-Klotho levels in older males. Additional studies would further explore these interactions and elucidate the pathogenesis of the potential effects of p-DCB exposure on aging.

Relationship between urinary dichlorophenols and cognitive function among people over 60 years old from NHANES

Studies have shown that exposure to dichlorophenols (DCPs) and their precursors might have potential neurotoxicity, which may be related to low cognitive function, but there are few large-scale, representative population data to explore the association between DCP exposure and cognitive function. We aimed to examine the relationship between urinary DCPs and cognitive function in the US older people. A total of 952 participants ≥ 60 years old from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2011-2014) were enrolled. The Consortium to Establish a Registry for Alzheimer's disease Word Learning subtest (CERAD W-L), the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST) were used to assess cognition. Multivariate logistic regression and restricted cubic spline (RCS) were used to evaluate the relationship between DCP exposure and cognitive function. A positive association between 2,5-DCP and the risk of bad performance of DSST was observed (P for trend = 0.024) after adjusting for the covariates. Compared to the lowest quartile, OR of DSST for the highest quartile of 2,5-DCP was 1.72 (95%CI:1.03-2.87, P = 0.039). There were no significant associations between DCPs and the other tests. The RCS plot showed an inverted J-shaped relationship between 2,5-DCP, 2,4-DCP, and the DSST score. The inflection points for the curves were found at 1.531 μg/L and 0.230 μg/L, respectively. On the right side of the inflection points, the DSST score dropped sharply. In subgroup analysis, those under 70 years old, smokers, and alcohol drinkers had a higher risk of bad performance in DSST when exposed to 2,5-DCP. The higher concentration of urinary DCPs is associated with a lower score of DSST in the US older people.

Early life exposure to indoor air pollutants and the risk of neurodevelopmental delays: The Japan Environment and Children's Study

Air pollution has been associated with childhood neurodevelopment. However, the role of indoor air pollution, especially volatile organic compounds (VOCs), on childhood neurodevelopment has been poorly explored to date. We investigated the association between indoor air pollutants and childhood neurodevelopment in 5,017 randomly selected children from the Japan Environment and Children's Study. When the participants reached 1.5 and 3 years of age, they were followed up with home visits and neurodevelopmental tests using the Ages and Stages Questionnaire (ASQ). At both ages, we collected indoor air samples for 1 week and measured 13 indoor air pollutants: particulate matter with an aerodynamic diameter of ≤2.5 μm, ozone, nitrogen dioxide, sulfur dioxide, and nine VOCs. The associations between air pollutants and ASQ scores were estimated using linear mixed effects models and weighted quantile sum regressions (WQS) at each age separately. Stratified analysis by sex was conducted. Exposure to m,p-xylene at the age of 3 was associated with lower communication, fine motor, and overall ASQ scores (coefficients: -0.18 [99% confidence intervals (CI): -0.35, -0.02], -0.23 [99 %CI: -0.43, -0.03], and - 0.72 [99 %CI: -1.41, -0.04] per 1 µg/m³ increase, respectively). Exposure to o-xylene at the age of 3 was associated with lower communication, gross motor, fine motor, and overall ASQ scores (coefficients: -0.48 [99 %CI: -0.90, -0.07], -0.45 [99 %CI: -0.78, -0.13], -0.65 [99 %CI: -1.14, -0.16], and -2.15 [99 %CI: -3.83, -0.47] per 1 µg/m³ increase, respectively). The WQS index was associated with lower gross motor ASQ scores at the age of 3 (coefficient: -0.27 [95 %CI: -0.51, -0.03] for one-unit WQS index increases), which was attributed to benzene (33.96%), toluene (26.02%), o-xylene (13.62%), and ethylbenzene (9.83%). Stratified analysis showed similar results. Although further investigations are required, our results suggest an association of neurodevelopmental delays with indoor low-level exposure to m,p-xylene and o-xylene in early life.

Development of an esophageal stricture following paradichlorobenzene mothball ingestion

A 2-year-old patient presented with a paradichlorobenzene mothball ingestion. The foreign body was removed with a straight Miller blade and a curved Allis clamp. Two weeks following the removal of the mothball, the patient developed solid food dysphagia due to an esophageal stricture. This complication after a short exposure to mothballs is unreported in the literature to date, making this a unique and interesting case. In addition, a comparison of the clinical presentation and treatment of naphthalene and paradichlorobenzene mothballs was reviewed in this article.

Mothball ingestion as a manifestation of pica, leading to paradichlorobenzene CNS toxicity

Background:

Pica is a poorly understood psychiatric disorder that presents with the ingestion of non-nutritious substances for unclear reasons. A high index of suspicion for unusual toxin exposure aids in the diagnosis of pica patients presenting with unexplained neurodegenerative features.

Methods:

We present a 47-year-old female with worsening gait over the past year. Prior to this, she was fully independent with activities of daily living, but is now mostly housebound due to frequent falls. Past medical history is significant for menorrhagia, iron deficiency anemia and pica. CBC and iron studies revealed iron deficiency with microcytic hypochromic anemia. MRI brain demonstrated symmetrical T2 hyperintensities within the middle cerebellar peduncles.

Results:

Differential diagnoses for her clinical deficits and imaging, including Spinocerebellar Ataxia, Multiple System Atrophy and Fragile X Tremor-Ataxia Syndrome, were excluded based on neurological assessment, family history and genetic PCR testing. Collateral history revealed a regular habit of mothball ingestion and serum paradichlorobenzene levels were elevated to 15mcg/mL. The patient was treated with iron replacement therapy and her symptoms gradually improved over several months.

Conclusion:

Iron deficiency anemia is commonly associated with pica, which can lead to toxin ingestion. A high index of suspicion for toxin ingestion in pica patients can immensely aid in the diagnosis. Mothball abuse secondary to pica may affect the CNS and can present with nonspecific neurodegenerative changes. To our knowledge, there have been no reported cases in the literature with paradichlorobenzene neurotoxicity predominantly affecting the middle cerebellar peduncles.

Exposure to Volatile Organic Compounds and Use of Feminine Hygiene Products Among Reproductive-Aged Women in the United States

Background: Feminine hygiene products (FHPs) are personal care products widely used by women. A few studies have detected some volatile organic compounds (VOCs) in FHPs, but no previous epidemiological studies have linked use of these products to human exposure to VOCs using biomarkers. Therefore, we evaluated whether the use of FHPs was associated with VOC exposures among reproductive-aged women in the United States. Materials and Methods: Data on 2432 women aged 20-49 years from National Health and Nutrition Examination Survey 2001-2004 were utilized. Self-reported use of feminine products (tampons, sanitary napkins, vaginal douches, sprays, powders, wipes/towelettes, and other products) was obtained from questionnaires. Survey-weighted linear regression models were used to estimate percent changes in VOC whole blood concentrations and 95% confidence intervals (CIs). Results: Black women had significantly more use of vaginal douching and significantly higher whole blood concentrations of 1,4-dichlorobenzene (DCB) (p < 0.0001). After adjusting for confounders, we observed a dose-response relationship between the frequency of vaginal douching in the past 6 months and 1,4-DCB concentrations. Compared with never users, women with occasional use (≤1 time/month) of vaginal douching had 18% (95% CI: -12% to 59%) higher concentrations, and those with frequent use (≥2 time/month) had 81% (95% CI: 2% to 221%) higher concentrations of 1,4-DCB (p for trend = 0.04). Use of feminine powder in the past month was significantly associated with 36% (95% CI: 0.4% to 83%) higher concentrations of ethylbenzene. Conclusions: Our findings suggest that differences in whole blood VOC concentrations might be explained by feminine hygiene practices. The presence of environmental chemicals in FHPs warrants further examination.

PDCB does not promote CNS autoimmunity in the context of genetic susceptibility but worsens its outcome

BACKGROUND

Para-dichlorobenzene (PDCB) is an aromatic hydrocarbon contained in mothballs that is potentially neurotoxic. A potential pathogenic role of PDCB in MS pathogenesis has been suggested.

METHODS

To determine the ability of chronic PDCB ingestion to induce CNS autoimmunity in a genetically susceptible mammalian species, naive myelin oligodendrocyte glycoprotein peptide (MOG_p)35-55 T cell receptor (TCR) transgenic mice (2D2) on the C57Bl/6 background were orally gavaged once daily with corn oil control, 125 mg/kg PDCB, or 250 mg/kg PDCB for 45 days. The incidence of spontaneous EAE is increased in this mouse strain.

RESULTS

Both PDCB treatment groups showed the same spontaneous incidence of EAE, an earlier disease onset, and a slight decrease in survival for 125 mg/kg PDCB mice compared to control mice. We were unable to detect any PDCB, or its metabolites 2,5-dichlorophenol, 2,5-dicholormethylsulfide, and 2,5-dichloromethylsulfone in the brain and spinal cord of control mice. In contrast, PDCB was readily detectable in both compartments in mice who received PDCB via oral gavage, with concentrations being significantly higher in the brain (p < 0.01). Levels of the metabolites 2,5-dichlorophenol and 2,5-dichloromethylsulfone were also significantly higher in brains compared to spinal cords.

CONCLUSION

Our study refutes the hypothesis that PDCB or its metabolites trigger spontaneous T cell-mediated CNS autoimmunity in the setting of genetic susceptibility. A slight increase in mortality with PDCB exposure may be due systemic toxicity of hydrocarbons.

Halide anions are formed from reactions between atomic metal anions and halogenated aromatic molecules

Atomic metal anions (AMAs) Fe^- , Cs^- , Cu^- and Ag^- were generated in the gas phase by collisionally decomposing the corresponding metal-oxalate anion. Mass selected AMAs were allowed to react with halogenated and nitrated molecules (C6H5Cl, C6H4Cl2, C6H3Cl3, C6H5I, C6H5Br and C6H5NO2) in the collision hexapole of a triple-quadrupole mass spectrometer. Observed reactions include the predominant formation of X^- (X = Cl, Br and I), as well as FeCl^- , FeCl2^- and FeCl3^- when Fe- reacted with the mono, di and tri-chlorobenzenes; reactions between 1,4-dichlorobenzene and Cs^- produced Cl^- , CsCl^- and CsCl2^- ; reactions involving iodobenzene also produced, CsI^- , CsI2^- and AgI^- . The results suggest that the reaction to form X^- (X = Cl, Br, I and NO2) may be a promising route to improving the detection efficiency by mass spectrometry for such analytes. Copyright © 2016 John Wiley & Sons, Ltd.