Household triclosan and triclocarban effects on the infant and maternal microbiome

A common antimicrobial additive increases colonic inflammation and colitis-associated colon tumorigenesis in mice

Triclosan (TCS) is a high-volume chemical used as an antimicrobial ingredient in more than 2000 consumer products, such as toothpaste, cosmetics, kitchenware, and toys. We report that brief exposure to TCS, at relatively low doses, causes low-grade colonic inflammation, increases colitis, and exacerbates colitis-associated colon cancer in mice. Exposure to TCS alters gut microbiota in mice, and its proinflammatory effect is attenuated in germ-free mice. In addition, TCS treatment increases activation of Toll-like receptor 4 (TLR4) signaling in vivo and fails to promote colitis in Tlr4^-/- mice. Together, our results demonstrate that this widely used antimicrobial ingredient could have adverse effects on colonic inflammation and associated colon tumorigenesis through modulation of the gut microbiota and TLR4 signaling. Together, these results highlight the need to reassess the effects of TCS on human health and potentially update policies regulating the use of this widely used antimicrobial.

Consumer Safety Considerations of Skin and Oral Microbiome Perturbation

Microbiomes associated with human skin and the oral cavity are uniquely exposed to personal care regimes. Changes in the composition and activities of the microbial communities in these environments can be utilized to promote consumer health benefits, for example, by reducing the numbers, composition, or activities of microbes implicated in conditions such as acne, axillary odor, dandruff, and oral diseases. It is, however, important to ensure that innovative approaches for microbiome manipulation do not unsafely disrupt the microbiome or compromise health, and where major changes in the composition or activities of the microbiome may occur, these require evaluation to ensure that critical biological functions are unaffected. This article is based on a 2-day workshop held at SEAC Unilever, Sharnbrook, United Kingdom, involving 31 specialists in microbial risk assessment, skin and oral microbiome research, microbial ecology, bioinformatics, mathematical modeling, and immunology. The first day focused on understanding the potential implications of skin and oral microbiome perturbation, while approaches to characterize those perturbations were discussed during the second day. This article discusses the factors that the panel recommends be considered for personal care products that target the microbiomes of the skin and the oral cavity.

Use of antibacterial toothpaste is associated with higher urinary triclosan concentrations in Asian immigrant women living in Vancouver, Canada

BACKGROUND

Triclosan is an antibacterial added to consumer products including toothpastes, cosmetics, and plastic cutting boards. Known to disrupt reproductive and hormonal functioning in animals, epidemiological studies indicate that exposure to triclosan may have similar effects on human health.

METHODS

100 women aged 19 to 45 years born in India or China, Hong Kong, and Taiwan new to the Vancouver (Canada) area were recruited in 2015-2016 by word of mouth, public advertisements, and contacts in health and cultural organizations. Participants completed an interview which queried potential sources of triclosan exposure at home and at work and their urine was tested for triclosan by GC-MS. Determinants of urinary triclosan were assessed by Wilcoxon signed-rank test.

RESULTS

Triclosan was detected in 62% of urine samples, with an overall GM of 14.5 μg/L (95% CI: 9.7-21.7 μg/L; range: <LOD to 1900 μg/L). Colgate Total® toothpaste users had higher urinary triclosan concentrations (median = 34.0 μg/L) than non-users (median = 2.5 μg/L, ρ < 0.001), a result which was unaffected by adjustment for age, income, BMI, and country of birth. South Asian born women had elevated urinary triclosan compared to East Asian born women.

CONCLUSION

Triclosan exposure via a specific antibacterial toothpaste brand was identified in reproductive age newcomer women in Canada. Health education around brushing teeth well while using lower toothpaste volumes or choosing triclosan-free toothpaste would reduce triclosan exposure.

Contaminant and Environmental Influences on Thyroid Hormone Action in Amphibian Metamorphosis

Aquatic and terrestrial environments are increasingly contaminated by anthropogenic sources that include pharmaceuticals, personal care products, and industrial and agricultural chemicals (i. e., pesticides). Many of these substances have the potential to disrupt endocrine function, yet their effect on thyroid hormone (TH) action has garnered relatively little attention. Anuran postembryonic metamorphosis is strictly dependent on TH and perturbation of this process can serve as a sensitive barometer for the detection and mechanistic elucidation of TH disrupting activities of chemical contaminants and their complex mixtures. The ecological threats posed by these contaminants are further exacerbated by changing environmental conditions such as temperature, photoperiod, pond drying, food restriction, and ultraviolet radiation. We review the current knowledge of several chemical and environmental factors that disrupt TH-dependent metamorphosis in amphibian tadpoles as assessed by morphological, thyroid histology, behavioral, and molecular endpoints. Although the molecular mechanisms for TH disruption have yet to be determined for many chemical and environmental factors, several affect TH synthesis, transport or metabolism with subsequent downstream effects. As molecular dysfunction typically precedes phenotypic or histological pathologies, sensitive assays that detect changes in transcript, protein, or metabolite abundance are indispensable for the timely detection of TH disruption. The emergence and application of 'omics techniques-genomics, transcriptomics, proteomics, metabolomics, and epigenomics-on metamorphosing tadpoles are powerful emerging assets for the rapid, proxy assessment of toxicant or environmental damage for all vertebrates including humans. Moreover, these highly informative 'omics techniques will complement morphological, behavioral, and histological assessments, thereby providing a comprehensive understanding of how TH-dependent signal disruption is propagated by environmental contaminants and factors.

Household composition and the infant fecal microbiome: The INSPIRE study

OBJECTIVES

Establishment and development of the infant gastrointestinal microbiome (GIM) varies cross-culturally and is thought to be influenced by factors such as gestational age, birth mode, diet, and antibiotic exposure. However, there is little data as to how the composition of infants' households may play a role, particularly from a cross-cultural perspective. Here, we examined relationships between infant fecal microbiome (IFM) diversity/composition and infants' household size, number of siblings, and number of other household members.

MATERIALS AND METHODS

We analyzed 377 fecal samples from healthy, breastfeeding infants across 11 sites in eight different countries (Ethiopia, The Gambia, Ghana, Kenya, Peru, Spain, Sweden, and the United States). Fecal microbial community structure was determined by amplifying, sequencing, and classifying (to the genus level) the V1-V3 region of the bacterial 16S rRNA gene. Surveys administered to infants' mothers identified household members and composition.

RESULTS

Our results indicated that household composition (represented by the number of cohabitating siblings and other household members) did not have a measurable impact on the bacterial diversity, evenness, or richness of the IFM. However, we observed that variation in household composition categories did correspond to differential relative abundances of specific taxa, namely: Lactobacillus, Clostridium, Enterobacter, and Klebsiella.

DISCUSSION

This study, to our knowledge, is the largest cross-cultural study to date examining the association between household composition and the IFM. Our results indicate that the social environment of infants (represented here by the proxy of household composition) may influence the bacterial composition of the infant GIM, although the mechanism is unknown. A higher number and diversity of cohabitants and potential caregivers may facilitate social transmission of beneficial bacteria to the infant gastrointestinal tract, by way of shared environment or through direct physical and social contact between the maternal-infant dyad and other household members. These findings contribute to the discussion concerning ways by which infants are influenced by their social environments and add further dimensionality to the ongoing exploration of social transmission of gut microbiota and the "old friends" hypothesis.

Ecological processes underpinning microbial community structure during exposure to subinhibitory level of triclosan

Ecological processes shaping the structure and diversity of microbial communities are of practical importance for managing the function and resilience of engineered biological ecosystems such as activated sludge processes. This study systematically evaluated the ecological processes acting during continuous exposure to a subinhibitory level of antimicrobial triclosan (TCS) as an environmental stressor. 16S rRNA gene-based community profiling revealed significant perturbations on the community structure and dramatic reduction (by 20-30%) in species diversity/richness compared to those under the control conditions. In addition, community profiling determined the prevalence of the deterministic processes overwhelming the ecological stochasticity. Analysis of both community composition and phenotypes in the TCS-exposed communities suggested the detailed deterministic mechanism: selection of TCS degrading (Sphingopyxis) and resistant (Pseudoxanthomonas) bacterial populations. The analysis also revealed a significant reduction of core activated sludge members, Chitinophagaceae (e.g., Ferruginibacter) and Comamonadaceae (e.g., Acidovorax), potentially affecting ecosystem functions (e.g., floc formation and nutrient removal) directly associated with system performance (i.e., wastewater treatment efficiency and effluent quality). Overall, our study provides new findings that inform the mechanisms underlying the community structure and diversity of activated sludge, which not only advances the current understanding of microbial ecology in activated sludge, but also has practical implications for the design and operation of environmental bioprocesses for treatment of antimicrobial-bearing waste streams.

Associations of prenatal exposure to polybrominated diphenyl ethers and polychlorinated biphenyls with long-term gut microbiome structure: a pilot study

Supplemental Digital Content is available in the text.

The gut microbiome is influenced by early-life exposures, but—despite potentially enormous implications for child health—is understudied in environmental epidemiology. This pilot study is one of the first to explore in utero exposures and long-term gut microbiome profiles. We examined the association between exposure to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) during pregnancy and the mid-childhood gut microbiome.

A longitudinal assessment of host-microbe-parasite interactions resolves the zebrafish gut microbiome's link to Pseudocapillaria tomentosa infection and pathology

BACKGROUND

Helminth parasites represent a significant threat to the health of human and animal populations, and there is a growing need for tools to treat, diagnose, and prevent these infections. Recent work has turned to the gut microbiome as a utilitarian agent in this regard; components of the microbiome may interact with parasites to influence their success in the gut, meaning that the microbiome may encode new anthelmintic drugs. Moreover, parasite infections may restructure the microbiome's composition in consistent ways, implying that the microbiome may be useful for diagnosing infection. The innovation of these utilities requires foundational knowledge about how parasitic infection, as well as its ultimate success in the gut and impact on the host, relates to the gut microbiome. In particular, we currently possess limited insight into how the microbiome, host pathology, and parasite burden covary during infection. Identifying interactions between these parameters may uncover novel putative methods of disrupting parasite success.

RESULTS

To identify interactions between parasite success and the microbiome, we quantified longitudinal associations between an intestinal helminth of zebrafish, Pseudocapillaria tomentosa, and the gut microbiome in 210 4-month-old 5D line zebrafish. Parasite burden and parasite-associated pathology varied in severity throughout the experiment in parasite-exposed fish, with intestinal pathologic changes becoming severe at late time points. Parasite exposure, burden, and intestinal lesions were correlated with gut microbial diversity. Robust generalized linear regression identified several individual taxa whose abundance predicted parasite burden, suggesting that gut microbiota may influence P. tomentosa success. Numerous associations between taxon abundance, burden, and gut pathologic changes were also observed, indicating that the magnitude of microbiome disruption during infection varies with infection severity. Finally, a random forest classifier accurately predicted a fish's exposure to the parasite based on the abundance of gut phylotypes, which underscores the potential for using the gut microbiome to diagnose intestinal parasite infection.

CONCLUSIONS

These experiments demonstrate that P. tomentosa infection disrupts zebrafish gut microbiome composition and identifies potential interactions between the gut microbiota and parasite success. The microbiome may also provide a diagnostic that would enable non-destructive passive sampling for P. tomentosa and other intestinal pathogens in zebrafish facilities.

Embracing microbes in exposure science

Although defined more broadly, exposure science has mainly focused on exposures to environmental chemicals and related stressors, such as airborne particulate matter. There is an opportunity for exposure science to contribute more substantially to improving public health by devoting more attention to microorganisms as key stressors and agents in exposure. The discovery that pathogenic microbes cause disease in humans precipitated a revolution in public health science and disease prevention. With a continued global urgency to address spread of pathogenic microbes, contributions of microorganisms to both infectious and noninfectious processes merit more attention from the exposure science community. Today, discoveries of the importance of the human microbiome as a determinant of health and disease are precipitating a second revolution. Emerging knowledge creates a major opportunity to expand the scope of exposure science to incorporate the human microbiome as a target and modulator of exposure. A study committee of the National Academies of Sciences, Engineering, and Medicine has defined a research strategy to address health risks that pertain to the interaction of environmental chemicals with the human microbiome. Some aspects of this strategy pose important challenges and opportunities for the exposure science community.

Triclosan, a common antimicrobial ingredient, on gut microbiota and gut health

Triclosan (TCS) is an antimicrobial compound incorporated into more than 2,000 consumer products. This compound is frequently detected in the human body and causes ubiquitous contamination in the environment, raising concerns about its impact on human health and environmental pollution. Our recent research showed that exposure to TCS exaggerates colonic inflammation and exacerbates development of colitis-associated colon tumorigenesis, via gut microbiome-dependent mechanisms. In this review, we discussed recent research about TCS, as well as other consumer antimicrobials, on the gut microbiome and gut health.

Inhaled nanomaterials and the respiratory microbiome: clinical, immunological and toxicological perspectives

Our development and usage of engineered nanomaterials has grown exponentially despite concerns about their unfavourable cardiorespiratory consequence, one that parallels ambient ultrafine particle exposure from vehicle emissions. Most research in the field has so far focused on airway inflammation in response to nanoparticle inhalation, however, little is known about nanoparticle-microbiome interaction in the human airway and the environment. Emerging evidence illustrates that the airway, even in its healthy state, is not sterile. The resident human airway microbiome is further altered in chronic inflammatory respiratory disease however little is known about the impact of nanoparticle inhalation on this airway microbiome. The composition of the airway microbiome, which is involved in the development and progression of respiratory disease is dynamic, adding further complexity to understanding microbiota-host interaction in the lung, particularly in the context of nanoparticle exposure. This article reviews the size-dependent properties of nanomaterials, their body deposition after inhalation and factors that influence their fate. We evaluate what is currently known about nanoparticle-microbiome interactions in the human airway and summarise the known clinical, immunological and toxicological consequences of this relationship. While associations between inhaled ambient ultrafine particles and host immune-inflammatory response are known, the airway and environmental microbiomes likely act as intermediaries and facilitate individual susceptibility to inhaled nanoparticles and toxicants. Characterising the precise interaction between the environment and airway microbiomes, inhaled nanoparticles and the host immune system is therefore critical and will provide insight into mechanisms promoting nanoparticle induced airway damage.

Consumer Antimicrobials on Gut Microbiota and Gut Health

Triclosan (TCS) is a high-volume chemical used as an antimicrobial ingredient in over 2000 consumer products such as toothpastes, cosmetics, and toys. Due to its widespread use, it causes ubiquitous contamination in the environment and is frequently detected in the human body, raising concerns about its impact on environmental pollution and human health. Our recent study showed that short-time exposure to low-dose TCS causes colonic inflammation, increases severity of colitis, and exacerbates colitis-associated colon tumorigenesis in mice, through gut microbiota- and Toll-like receptor 4 (TLR4)-dependent mechanisms. In addition, we demonstrate that beyond TCS, other antimicrobial chemicals used in consumer products also exaggerate colitis and colon cancer in mice. Together, these results highlight the importance to further evaluate these consumer antimicrobials on gut health, to develop potential further regulatory policies.

Flux, Impact, and Fate of Halogenated Xenobiotic Compounds in the Gut

Humans and their associated microbiomes are exposed to numerous xenobiotics through drugs, dietary components, personal care products as well as environmental chemicals. Most of the reciprocal interactions between the microbiota and xenobiotics, such as halogenated compounds, occur within the human gut harboring diverse and dense microbial communities. Here, we provide an overview of the flux of halogenated compounds in the environment, and diverse exposure routes of human microbiota to these compounds. Subsequently, we review the impact of halogenated compounds in perturbing the structure and function of gut microbiota and host cells. In turn, cultivation-dependent and metagenomic surveys of dehalogenating genes revealed the potential of the gut microbiota to chemically alter halogenated xenobiotics and impact their fate. Finally, we provide an outlook for future research to draw attention and attract interest to study the bidirectional impact of halogenated and other xenobiotic compounds and the gut microbiota.

Household triclosan and triclocarban effects on the infant and maternal microbiome

In 2016, the US Food and Drug Administration banned the use of specific microbicides in some household and personal wash products due to concerns that these chemicals might induce antibiotic resistance or disrupt human microbial communities. Triclosan and triclocarban (referred to as TCs) are the most common antimicrobials in household and personal care products, but the extent to which TC exposure perturbs microbial communities in humans, particularly during infant development, was unknown. We conducted a randomized intervention of TC‐containing household and personal care products during the first year following birth to characterize whether TC exposure from wash products perturbs microbial communities in mothers and their infants. Longitudinal survey of the gut microbiota using 16S ribosomal RNA amplicon sequencing showed that TC exposure from wash products did not induce global reconstruction or loss of microbial diversity of either infant or maternal gut microbiotas. Broadly antibiotic‐resistant species from the phylum Proteobacteria, however, were enriched in stool samples from mothers in TC households after the introduction of triclosan‐containing toothpaste. When compared by urinary triclosan level, agnostic to treatment arm, infants with higher triclosan levels also showed an enrichment of Proteobacteria species. Despite the minimal effects of TC exposure from wash products on the gut microbial community of infants and adults, detected taxonomic differences highlight the need for consumer safety testing of antimicrobial self‐care products on the human microbiome and on antibiotic resistance.

Early life Triclosan exposure and child adiposity at 8 Years of age: a prospective cohort study

BACKGROUND

Triclosan is an antimicrobial agent that may affect the gut microbiome and endocrine system to influence adiposity. However, little data from prospective studies examining prenatal and childhood exposures exist. We investigated the relationship between multiple, prospective early life measure of triclosan exposure and child adiposity.  METHODS: In a prospective cohort of 220 mother-child pairs from Cincinnati, OH (enrolled 2003-2006), we quantified triclosan in urine samples collected twice during pregnancy, annually from 1 to 5 years of age, and once at 8 years. We assessed child adiposity at age 8 years using body mass index (BMI), waist circumference, and bioelectric impedance. We estimated covariate-adjusted associations of child adiposity with a 10-fold increase in average prenatal, average early childhood (average of 1-5 years), and 8-year triclosan concentrations.

RESULTS

Among all children, there was no association between triclosan and child adiposity. While urinary triclosan concentrations at all three time periods were weakly, imprecisely, and inversely associated with all three measures of adiposity among girls, these associations did not differ significantly from those in boys (sex x triclosan p-values> 0.35). Among girls, the strongest associations were generally observed for prenatal triclosan when we adjusted for all three triclosan concentrations and covariates in the same model; BMI z-score (β: -0.13; 95% CI: -0.42, 0.15), waist circumference (β: - 1.7 cm; 95% CI: -4.2, 0.7), and percent body fat (β :-0.6; 95% CI: -2.7, 1.3). In contrast, the associations between triclosan concentrations and adiposity measures were inconsistent among boys.

CONCLUSION

We did not observe evidence of an association of repeated urinary triclosan concentrations during pregnancy and childhood with measures of child adiposity at age 8 years in this cohort.