Nicolas Van Larebeke

Background: E-cigarette use has risen sharply among young never-smokers, largely driven by the availability of several thousand appealing flavours. This narrative review synthesises evidence on the health effects of vaping, flavour toxicology and attractiveness, designs and outcomes of flavour bans, and complementary measures. Methods: Peer-reviewed publications and institutional reports (up to January 2026) were retrieved from PubMed, Web of Science, Google Scholar, and reference lists of included articles. Evidence from about 200 references was synthesised by a multidisciplinary working group. Results: Although flavouring substances are generally considered safe for ingestion, their inhalation toxicity remains uncertain. In vitro and in vivo studies have reported oxidative stress, inflammation, cytotoxicity, impaired ciliary function, transcriptomic changes, genotoxicity, and DNA damage. These findings—along with the strong youth appeal of fruit/sweet flavours, the inconclusive effects of flavours on smoking cessation, and persisting uncertainties—support banning non-tobacco e-cigarette flavours under the precautionary principle. Flavour bans can reduce e-cigarette use and initiation, especially among young adults, although partial substitution towards combustible cigarettes has been reported in some U.S. states. Policy success requires effective enforcement, prevention of industry circumvention, curbing cross-border sales, and closing regulatory loopholes—ideally at the international level (e.g., EU-wide). Conclusions: E-cigarette flavours may increase vaping toxicity and strongly appeal to youth, justifying flavour bans to prioritise youth protection. To maximise effectiveness, accompanying measures and sustained investment in tobacco prevention, youth education, and accessible evidence-based smoking cessation support are essential.

Background: We have recently published (van Larebeke, Environ Health 24:34, 2025) consistent and biologically relevant associations of PFAS serum concentrations with sex hormone levels in male adolescents and with a significant delay in physiological processes occurring during puberty in girls and boys. Associations with thyroid hormones differed significantly by sex with only for boys significant positive associations of FT3 with PFOA, PFHxS and PFNA. Here we report a follow-up analysis to test a work hypothesis stating that, as can be expected for receptor mediated effects, the observed associations would be stronger at lower PFAS serum concentrations (e.g. below the median) than at higher PFAS serum concentrations. Main body: To allow for a comparison between associations of biological/health effects with PFAS concentrations below or above median values, PFAS concentrations without log transformation were used in linear multiple regression with continuous effect parameters, logistic models with binary effect parameters, and Ordinal Multinomial Probit models with ordinal effect parameters. Regression coefficients and other statistical parameters were calculated with the Statistica 14.0 program. Significance of the difference between a regression coefficient observed for an association with a certain PFAS below the median serum concentration compared to above the median was assessed using a two‑tailed Wald test. The median PFAS serum values observed in our study were below present health based guidance values. Consistent with our working hypothesis, the lower exposed subpopulations (with serum concentrations below the median) had a greater change in outcome per unit increase in PFAS exposure (a stronger regression coefficient) than the higher exposed subpopulations concerning 72 of the 84 significant associations described previously and this was most pronounced for PFHxS, and to a lesser extent for PFOS(branched), PFOA and sum parameters. Continuous piecewise linear models, models with a quadratic term and, in the range of PFAS concentrations where sufficient data were present, also weighted least square graphs, yielded results supporting stronger regression coefficients below median PFAS serum concentrations. Conclusion: Our observations suggest that an important part of the endocrine disrupting effect of PFAS on adolescents occurs at serum levels below present health based guidance values.

Near Antwerp a 3M factory has been active since 1971 emitting PFAS, mainly PFOS, in the local environment. Production of C8 compounds was stopped in 2002, production of other PFAS continued until 2024. This study aimed to examine the association between internal PFAS concentrations and thyroid hormones, sexual hormones, and pubertal development in adolescents living in the neighborhood of the factory. We measured PFAS in serum of 146 female and 139 male adolescents. For males sex hormones (LH, testosterone, estradiol, progesterone, inhibin B, FSH) and SHBG were measured in serum. For males and females we assessed serum thyroid hormone levels (TSH, T3, T4 and T3/T4) and pubertal development parameters self-assessed through a standardized questionnaire. Associations between PFAS concentrations and effect biomarkers/health effects were assessed through Generalized Estimating Equations (GEE), using linear models for continuous outcomes, logistic models for binary outcomes, and proportional odds models for ordinal outcomes. For males LH, total and bioavailable testosterone showed significant negative associations with PFHxS and PFOA. LH and bioavailable testosterone also showed significant negative associations with other PFAS compounds. SHBG showed significant positive associations with PFDA, PFNA, PFHxS, PFOS and the sum of the linear forms of PFOS, PFOA, PFNA and PFHxS. Males’ length and growth spurt showed significant negative associations with PFOS, PFOA and PFAS sum parameters and length and growth spurt separately also with other PFAS compounds. For females growth spurt showed significant negative association with PFOA and a significant positive association with PFOS(branched). For both males and females body hair development showed significant negative associations with PFHxS, and, for males and females separately also with other PFAS compounds. For females, breast development showed significant negative associations with PFOA, pubertal development scale showed significant negative associations with PFOA, PFHxS, PFOS(linear) and the sum of 4 PFAS. For males, TSH showed a significant negative association with PFDA and FT3 showed significant positive associations with PFOA, PFOA and PFNA. For females, FT3 showed a significant negative association with PFOS(branched). We observed significant, consistent and biologically relevant associations of PFAS serum concentrations with sex hormone and SHBG levels in male adolescents. Moreover, a significant delay in physiological processes occurring in puberty was observed in females and males. Associations with thyroid hormones differed significantly by sex

Contrary to the initial hypothesis, Flemish adolescents who reported consuming organic food at least 7.5 times per week did not exhibit reduced internal exposure to the tested recently used pesticides. After adjustment for gender, age, country of origin, socioeconomic status, body mass index, consumption of high-fat foods and foods linked to organic food consumption, and concerning organochlorine derivatives and lead, additional adjustment for the duration of breastfeeding expressed in weeks, they displayed slightly elevated internal exposure to organochlorine derivatives, lead, methyl arsenate, and toxic relevant arsenic. A comparison was also made between the correlation of internal exposure to pollutants with the frequency of organic food consumption on one hand and the total consumption of equivalent products from all sources on the other. Regarding potatoes, vegetables, and fruits, no clear trends were observed. Regarding eggs, there was a trend towards higher internal exposures with organic food consumption, significant for trans-nonachlor, PCB118, and 2,4-dichlorophenoxyacetic acid, and marginally significant for glyphosate. For dairy, there was a trend towards higher internal exposures with organic food consumption, significant for perfluorononanoic acid and marginally significant for PCB153. Regarding nuts and seeds, the higher internal exposure to dichlorophenoxyacetic acid and the lower exposure to 3-phenoxybenzoic acid were marginally significant, while there was also a trend towards higher internal exposure to other pollutants with organic food consumption, significant for PCB118, PCB153, and sum PCBs, and marginally significant for trans-nonachlor. Concerning breakfast cereals and muesli, no clear trends were observed.

Firefighters are exposed via multi-route exposure to a multitude of chemicals (PAHs, VOCs, flame retardants, dioxins, etc.) that may cause acute and long-term health effects. The dermal absorption of contaminants is a major contributor to the overall exposure and can be reduced by wearing appropriate personal protective equipment. As leather firefighters’ gloves cannot be decontaminated regularly by wet cleaning, many Belgian firefighters wear supplementary undergloves made of nitrile butadiene rubber (NBR) to protect against the accumulation of toxicants. However, the safety of this practice has been questioned. In this commentary, the current practice and risks are outlined for the first time, assessed by an interdisciplinary working group of the Belgian Superior Health Council. As NBR sticks to the skin more at high temperatures, the contact time on removal will be prolonged, posing an additional risk for deeper burns. However, based on the physicochemical properties of NBR and the existing experience of firefighters and burn centers, it is estimated that such incidents occur relatively rarely in practice. On the other hand, the risk of repeated exposure to contaminated gloves if no undergloves are worn is unacceptable. Despite the slightly increased risk for deeper burns, it is concluded that wearing disposable NBR gloves under regular firefighters’ gloves is an appropriate and effective preventive measure against toxic contamination. The nitrile butadiene rubber must always be fully covered to avoid any contact with the heat.

Background: The successive FLEHS campaigns assess internal exposure to pollutants and associated early biological and health effects in participants of different age groups. Materials and methods: Mother–newborn pairs (N = 220 in 2008–2009, age 18–42 years; N = 269 in 2013–2014, age 18–44 years), 197 adolescents 14–15 years (2010–2011), 201 adults 20–40 years (2008–2009) and 205 adults 50–65 years (2014) were recruited. For the various groups of subjects different sets of PFAS were assessed. Perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorobutane sulfonate (PFBS) were determined in cord plasma and peripheral serum as these were the PFAS compounds for which we had access to high quality measurements and which were expected to be present in the highest concentrations. Participants filled out a questionnaire based on the European Community Respiratory Health Survey questionnaire on asthma and allergy. In these cross-sectional studies associations were assessed using stepwise multiple logistic regression, with confounders (including smoking and familial occurrence of the disease) and potential covariates selected on the basis of experience in our previous studies and a literature search. Forest plots of odds ratios summarize the associations between the various PFAS on the one hand and the different immune outcomes on the other hand. Results: For several self-reported immune system-related diseases inverse associations with PFAS serum concentrations were observed. These inverse associations were more pronounced in mothers and adults than in adolescents. A significant inverse association was observed in adults and mothers (for mothers based on measurements on cord plasma) between PFNA, PFOS, and PFHxS and asthma (for mothers also for PFOA), in mothers between PFHxS, PFNA and PFOS and allergic rhinitis, in mothers and adults between PFHxS and PFOS and some forms of allergy (for mothers also for PFOA), in adults between PFOA and eczema, and in adolescents between PFOS and systemic allergy. Conclusion: Internal exposure to PFAS was associated with changes in immunological processes consistent with what has been reported in the literature. Whereas these changes were observed in many publications to be associated with adverse health effects, our findings suggest that they can also lead to inverse associations with certain immune system-related diseases.

Background: PFAS are persistent, bioaccumulative compounds repelling water, oil and stains which are widely used. There is mounting evidence linking exposure to a range of adverse health outcomes including renal, hepatic, immunotoxic, reproductive, endocrine disrupting and carcinogenic effects. PFAS possibly also induce neurobehavioral and developmental effects. Within Flanders Environment and Health Studies (FLEHS) internal exposure to PFAS and relevant health effects are assessed since 2008. Results: Adolescents 14–15 y (2010–2011) living in an industrially contaminated area (without known PFAS contamination) and adults 50–65 y (2014) randomly sampled from the general Flemish population using a stratified clustered multi-stage design, were recruited. For the adolescents perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were measured in serum, for the adults PFOS, PFOA, perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA) and perfluorobutane sulfonate (PFBS). In adolescents the Neurobehavioral Evaluation System (NES3) computerized battery of tests developed to study the neurological effects of an exposure to environmental agents was applied. The adults did the Stroop test, the NES3 Continuous Performance Test and the NES3 Digit Span Test. In adolescents sleepiness, masculinity and femininity were assessed via the Epworth Sleepiness Scale and Personal Attributes Questionnaires, respectively. In adolescents PFOA was associated with significantly increased somnolence, and PFOS with a significant inverse association with boys’ femininity and with girls’ masculinity. In adolescents, PFAS were also associated with a marginal decrease in sustained attention (PFOS) and cognitive performance (PFOA) and a significant decrease in short-term memory (PFOS). However, in older adults PFOS was associated with a significant increase in the capacity to pay attention and PFHxS with a significant increase in sustained attention. Conclusion: Our observations point to neurobehavioral and cognitive effects of PFAS. The neurobehavioral effects might in part result from the changes in sex hormone levels that have been reported to be associated with internal exposure to PFAS. Interestingly, whereas in relation to cognition some adverse effects were recorded for adolescents, for elderly persons our observations rather suggest possible weak positive effects with respect to cognition. Our observations might be in line with the view that PFAS have many, sometimes contrasting health effects.

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants of public health concern. Multiple biological mechanisms have been hypothesized to contribute to PAHs-associated adverse health effects. Little is known about the impact of PAHs on endocrine stress and inflammation in adolescence. We examined 393 Flemish adolescents (14–15 years) cross-sectionally, measured urinary concentrations of hydroxylated naphthalene, fluorene, phenanthrene and pyrene metabolites, and calculated the sum of all measured metabolites. We determined hair cortisol concentration (HCC) as endocrine stress biomarker, leucocyte counts and neutrophil–lymphocyte ratio (NLR) in peripheral blood as inflammatory biomarkers, and urinary 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG) concentration as oxidative stress biomarker. Exposure–response associations were analyzed by multiple regression, adjusted for a priori selected covariates. A doubling of 1-hydroxypyrene concentration was associated with a factor of 1.13 (95% CI: 1.03, 1.24) increase in HCC and a factor of 1.07 (95% CI: 1.02, 1.13) increase in 8-oxodG. Doublings of 2- and 3-hydroxyphenanthrene concentrations were associated with a factor of 1.08 (95% CI: 1.02, 1.14) and 1.06 (95% CI: 1.00, 1.12) increase in 8-oxodG, respectively. Doubling of 2-hydroxyphenanthrene and of the sum of 2- and 3-hydroxyfluorene was associated with, respectively, a factor of 1.08 (95% CI: 1.02, 1.14) and 1.06 (95% CI: 1.01, 1.13) increase in NLR. Our results indicate the glucocorticoid pathway as a potential target for PAH exposure in adolescents and suggest oxidative stress, endocrine stress, and inflammation in adolescence as underlying mechanisms and early markers for PAH-related adverse health effects.

Human biomonitoring (HBM) monitors levels of environmental pollutants in human samples, which often is a topic of concern for residents near industrially contaminated sites (ICSs). Around an ICS area in Menen (Belgium), including a (former) municipal waste incinerator and a metal recovery plant, increasing environmental concentrations of dioxins and polychlorinated biphenyls (PCBs) were observed, causing growing concern among residents and authorities. The local community succeeded in convincing the responsible authorities to investigate the problem and offer research funding. Persistent organic pollutants (POPs) were measured in two consecutive HBM studies (2002–2006 and 2010–2011), in the context of the Flemish Environment and Health Study (FLEHS), as well as in soil and locally produced food. Meanwhile, local authorities discouraged consumption of locally produced food in a delineated area of higher exposure risk. Ultimately, HBM and environmental data enabled tailored dietary recommendations. This article demonstrates the usefulness of HBM in documenting the body burdens of residents near the ICS, identifying exposure routes, evaluating remediating actions and providing information for tailored policy strategies aiding to further exposure reduction. It also highlights the role of the local stakeholders as an example of community-based participatory research and how such an approach can create societal support for research and policy.