Exposure to selected preservatives in personal care products: case study comparison of exposure models and observational biomonitoring data

Reviewing the variability in urinary concentrations of non-persistent organic chemicals: evaluation across classes, sampling strategies and dilution corrections

Various biomonitoring studies have been carried out to investigate the exposure of populations by measuring non-persistent organic chemicals in urine. To accurately assess the exposure, study designs should be carefully developed to maximise reproducibility and achieve good characterization of the temporal variability. To test these parameters, the intraclass correlation coefficients (ICCs) are calculated from repeated measurements and range from poor (<0.4) to excellent (≥0.75). Several studies have reported ICCs based on diverse study designs, but an overview, including recommendations for future studies, was lacking. Therefore, this review aimed to collect studies describing ICCs of non-persistent organic chemicals, discuss variations due to study design and formulate recommendations for future studies. More than 60 studies were selected, considering various chemical classes: bisphenols, pyrethroids, parabens, phthalates, alternative plasticizers and phosphate flame retardants. The variation in ICCs for an individual chemical was high (e.g. ICC of propyl paraben = 0.28-0.91), showing the large impact of the study design and of the specific exposure sources. The highest ICCs were reported for parabens (median = 0.52), while lowest ICCs were for 3-phenoxybenzoic acid (median = 0.08) and bisphenol A (median = 0.20). Overall, chemicals that had an exposure source with high variation, such as the diet, showed lower ICCs than those with more stable exposure sources, such as indoor materials. Urine correction by specific gravity had an overall positive effect on reducing the variability of ICCs. However, this effect was mostly seen in the adult population, while specific compounds showed less variation with creatinine correction. Single samples might not accurately capture the exposure to most non-persistent organic chemicals, especially when small populations are sampled. Future studies that examine compounds with low ICCs should take adequate measures to improve accuracy, such as correcting dilution with specific gravity or collecting multiple samples for one participant.

Updating exposure assessment for skin sensitization quantitative risk assessment for fragrance materials

In 2008, a proposal for assessing the risk of induction of skin sensitization to fragrance materials Quantitative Risk Assessment 1 (QRA1) was published. This was implemented for setting maximum limits for fragrance materials in consumer products. However, there was no formal validation or empirical verification after implementation. Additionally, concerns remained that QRA1 did not incorporate aggregate exposure from multiple product use and included assumptions, e.g. safety assessment factors (SAFs), that had not been critically reviewed. Accordingly, a review was undertaken, including detailed re-evaluation of each SAF together with development of an approach for estimating aggregate exposure of the skin to a potential fragrance allergen. This revision of QRA1, termed QRA2, provides an improved method for establishing safe levels for sensitizing fragrance materials in multiple products to limit the risk of induction of contact allergy. The use of alternative non-animal methods is not within the scope of this paper. Ultimately, only longitudinal clinical studies can verify the utility of QRA2 as a tool for the prevention of contact allergy to fragrance materials.

Perspectives on advancing consumer product exposure models

Predictive models are used to estimate exposures from consumer products to support risk management decision-making. These model predictions may be used alone in the absence of measured data or integrated with available exposure data. When different models are used, the resulting estimates of exposure and conclusions of risk may be disparate and the origin of these differences may not be obvious. This Perspectives Paper provides recommendations that could promote more systematic evaluation and a wider range of applicability of consumer product exposure models and their predictions, improve confidence in model predictions, and result in more accurate communication of consumer exposure model estimates. Key insights for the exposure science community to consider include: consistency in product descriptions, exposure routes, and scenarios; consistent and explicit definitions of exposure metrics; situation-dependent benefits from using one or multiple models; distinguishing between model algorithms and exposure factors; and corroboration of model predictions with measured data.

Aggregate exposure assessment using cosmetic co-use scenarios: II. Application and validation for phthalates

Aggregate exposure assessments using co-use scenarios could provide more realistic estimations than single product exposure assessment. Co-use scenarios for cosmetic products were determined from a ranking of the frequency of occurrence of co-use patterns and the number of cosmetics used. We conducted aggregate exposure assessments using the co-use scenarios and validated the new methodology by comparing the results to those of a receptor-based aggregate exposure assessment. The aggregate exposures of di(2-ethylhexyl)phthalate (DEHP), di-n-butyl phthalate (DnBP) and diethyl phthalate (DEP) in cosmetics were estimated by co-use scenarios for cosmetics. The co-use scenario-based AED increased with the number of cosmetics in the co-use scenarios, and was higher in female and younger groups. The major contributors in females were facial cream for DEHP, nail polish for DnBP, and shower cologne or perfume for DEP. The major contributors in males were body lotion for DEHP, facial sunscreen for DnBP, and hair styling product for DEP. The distribution of the co-use scenario based AEDs displayed a similar trend to that of the receptor-based AEDs, with the 95th percentiles of the AED slightly underestimated in the co-use scenario. The applied methodology could provide reasonable aggregate exposures with relatively few resources required.

Is It Realistic to Propose Determination of a Lifetime Internal Exposome?

Biomonitoring of xenobiotics has been performed for many years in occupational and environmental medicine. It has revealed hidden exposures and the exposure of workers could be reduced. Although most of the toxic effects of chemicals on humans were discovered in workers, the scientific community has more recently focused on environmental samples. In several countries, urinary and blood samples have been collected and analyzed for xenobiotics. Health, biochemical, and clinical parameters were measured in the biomonitoring program of the Unites States. The data were collected and evaluated as group values, comparing races, ages, and gender. The term exposome was created in order to relate chemical exposure to health effects together with the terms genome, proteome, and transcriptome. Internal exposures were mostly established with snapshot measurements, which can lead to an obvious misclassification of the individual exposures. Albumin and hemoglobin adducts of xenobiotics reflect the exposure of a larger time frame, up to 120 days. It is likely that only a small fraction of xenobiotics form such adducts. In addition, adduct analyses are more work intensive than the measurement of xenobiotics and metabolites in urine and/or blood. New technology, such as high-resolution mass spectrometry, will enable the discovery of new compounds that have been overlooked in the past, since over 300,000 chemicals are commercially available and most likely also present in the environment. Yet, quantification will be challenging, as it was for the older methods. At this stage, determination of a lifetime internal exposome is very unrealistic. Instead of an experimental approach with a large number of people, which is economically and scientifically not feasible, in silico methods should be developed further to predict exposure, toxicity, and potential health effects of mixtures. The computer models will help to focus internal exposure investigations on smaller groups of people and smaller number of chemicals.

Assessing Human Exposure to Chemicals in Materials, Products and Articles: The International Risk Management Landscape for Phthalates

Risk-based chemical safety assessments are increasingly being conducted to support chemical management decisions and informed substitution to protect public health. Rapid evaluation and prioritization of large numbers of chemicals used in materials, products, and other indoor articles has become a major focus of chemical risk management strategies. Internationally, although a shared understanding of the value of rapid risk-based evaluations appears to be emerging, implementation strategies and associated management decisions vary from one agency and jurisdiction to another. This paper highlights the international chemical risk management landscape focusing on phthalates as an example, and reviews how phthalate exposure assessments have been performed, resulting at times in different decisions based on the application of scientific information within different policy contexts. In general, the need for efficient and effective risk-based assessment approaches is driving increased needs for high-quality exposure data and validated, mechanistic exposure models. Further development of mechanistic models and related parameters will reduce uncertainties in exposure estimates and support scientific risk-based evaluations of chemical/product combinations for a variety of decisions.