Human Toxicity

Exposure estimates of parabens from personal care products compared with biomonitoring data in human hair from Northeast China

Parabens (PBs), a class of endocrine-disrupting chemicals (EDCs), are extensively used as additives in personal care products (PCPs); however, distinguishing between endogenous and exogenous contamination from PCPs in hair remains a challenge. We conducted a comprehensive analysis of the levels, distribution patterns, impact factors, and sources of PBs in 119 human hair samples collected from Changchun, northeast China. The detection rates of methylparaben (MeP), propylparaben (PrP), and ethylparaben (EtP) in hair samples were found to be 100%. The concentration of PBs in hair followed the order of MeP (57.48 ng/g) > PrP (46.40 ng/g) > EtP (6.80 ng/g). The concentration of PrP in female hair was significantly higher (65.38 ng/g) than that observed in male hair (7.82 ng/g) (p < 0.05). The levels of excretion rates of MeP (ERMeP) and excretion rates of PrP (ERPrP) in the hair-dying samples (ERMeP: 17.89 ng/day; ERPrP: 14.15 ng/day) were found to be 2.52 and 2.40 times higher, respectively, compared to the non-hair-dying samples (ERMeP: 7.09 ng/day; ERPrP: 6.05 ng/day). However, the system exposure dosage (SED) results revealed that although hair dyes exhibited higher PBs, human exposure was found to be lower than certain PCPs. The results of the correlation analysis revealed that toner, face cream, body lotion, and hair conditioner were identified as the primary sources of PBs in male hair. Furthermore, the human exposure resulting from the utilization of female hair dye and serum exhibited a positive correlation with hair ERMeP and ERPrP levels, indicating in the screening of samples, excluding hair samples using hair dye and haircare essential oil can effectively avoid the interference caused by exogenous contamination from PCPs.

Application of selected life cycle occupational safety methods to the case of electricity production from pyro-oil

Life cycle thinking is a necessary component in preventing the shifting of burden along the life cycle and from one impact category to another. For this reason, many have focused on integrating life cycle thinking into occupational risk assessment. The resultant methods have different properties in terms of scope and outcomes. Literature has been reviewed for life cycle occupational risk assessment methodologies, and 3 methods (life cycle inherent toxicity (LCIT) method, work environment characterization factors (WE-CFs) method, and life cycle risk assessment (LCRA) method) have been selected and applied in a case study of electricity production from pyro-oil to identify suitability and research gaps in the existing literature. The results of the LCIT method were highly heterogenous over life cycle of electricity production. For the current case, the major cancer and non-cancer impacts originated from the same life cycles. The results from WE-CFs method were highly heterogenous over the life cycle of electricity production as well. Agriculture contributed the most to the occupational risks. In the LCRA method, averaging caused the information about the frequency of the risks over life cycle to be lost. The method showed the well-known bargaining between accuracy and simplicity when complex systems are considered. Results from this method were quite homogenous among life cycles, due to the averaging effect. Detailed reporting and follow-up of the worker health issues can enable a more accurate application of the WE-CFs method. The overall results showed that it was possible to apply these 3 methodologies for the EU-28 region.

Multi-pathway exposure modeling of chemicals in cosmetics with application to shampoo

We present a novel multi-pathway, mass balance based, fate and exposure model compatible with life cycle and high-throughput screening assessments of chemicals in cosmetic products. The exposures through product use as well as post-use emissions and environmental media were quantified based on the chemical mass originally applied via a product, multiplied by the product intake fractions (PiF, the fraction of a chemical in a product that is taken in by exposed persons) to yield intake rates. The average PiFs for the evaluated chemicals in shampoo ranged from 3×10(-4) up to 0.3 for rapidly absorbed ingredients. Average intake rates ranged between nano- and micrograms per kilogram bodyweight per day; the order of chemical prioritization was strongly affected by the ingredient concentration in shampoo. Dermal intake and inhalation (for 20% of the evaluated chemicals) during use dominated exposure, while the skin permeation coefficient dominated the estimated uncertainties. The fraction of chemical taken in by a shampoo user often exceeded, by orders of magnitude, the aggregated fraction taken in by the population through post-use environmental emissions. Chemicals with relatively high octanol-water partitioning and/or volatility, and low molecular weight tended to have higher use stage exposure. Chemicals with low intakes during use (<1%) and subsequent high post-use emissions, however, may yield comparable intake for a member of the general population. The presented PiF based framework offers a novel and critical advancement for life cycle assessments and high-throughput exposure screening of chemicals in cosmetic products demonstrating the importance of consistent consideration of near- and far-field multi-pathway exposures.