Auflistung nach Autor:in "Küpper, Katja"

Gerade angezeigt 1 - 2 von 2

A biomonitoring study assessing the exposure of young German adults to butylated hydroxytoluene (BHT)
(2020) Schmidtkunz, Christoph; Kolossa-Gehring, Marike; Küpper, Katja; Weber, Till
The antioxidant 2,6-di-tert-butyl-4-methylphenol (butylated hydroxytoluene, BHT) is used ubiquitously in food, cosmetics, pharmaceuticals, fuels, plastics, rubbers and many other products. Therefore, exposure of the general population to this substance is likely. We analyzed the BHT metabolite 3,5-di-tert-butyl-4-hydroxybenzoic acid ("BHT acid") in 24-h urine samples from the German Environmental Specimen Bank with the aim of gaining a better understanding of the internal burden of BHT in young nonspecifically exposed adults. The study population consisted of students between 20 and 29 years of age at the time of sampling, all from Halle/Saale in Central Germany. In total, 329 samples collected in the years 2000, 2004, 2008, 2012, 2015, and 2018 were measured by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). BHT acid was detected above the limit of quantification (0.2 My g/L) in 98% of the samples. The median of the measured concentrations was 1.06 My g/L and 1.24 My g/g creatinine respectively, the median of the daily excretion was 1.76 My g/24 h and - additionally normalized for body weight - 26.8 ng/24 h * kg bw respectively. The corresponding 90th percentiles were 3.28 My g/L, 3.91 My g/g creatinine, 5.05 My g/24 h, and 81.9 ng/24 h * kg bw. Medians of creatinine-corrected values were slightly higher in women than in men, while the opposite situation was observed for the volume concentrations and the 24-h excretion values (not corrected for body weight). Values simultaneously normalized both for 24-h excretion and body weight did not exhibit any significant differences between males and females, probably indicating a virtually identical magnitude of exposure for both genders. The background exposure of the investigated population was found to be largely constant since the year 2000, with only weak temporal trends at most. Daily intakes were estimated from excretion values and found to be largely below the acceptable daily intake (ADI) of BHT at 0.25 mg/kg bw: our worst-case estimate is a daily BHT intake of approximately 0.1 mg/kg bw at the 95th percentile level. However, these intake assessments rely on very limited quantitative data regarding human metabolism of BHT. © 2020 Elsevier GmbH. All rights reserved.
A time trend of urinary 4-methylbenzylidene camphor metabolites in young adults from Germany
(2023) Schmidtkunz, Christoph; Kolossa-Gehring, Marike; Küpper, Katja; Weber, Till
4-methylbenzylidene camphor (4-MBC) is used as a UV-B filter in cosmetics. Two oxidized metabolites of 4-MBC - 3-(4-carboxybenzylidene)camphor (cx-MBC) and 3-(4-carboxybenzylidene)-6-hydroxycamphor (cx-MBC-OH) - were analyzed in 250 24-h urine samples from young adults in Germany. The samples were from the German Environmental Specimen Bank (ESB) and represented exposure in the years 1995, 2005, 2010, 2015 and 2019. A UHPLC-MS/MS method enabled the sensitive determination of both metabolites, with limits of quantifi cation at 0.15 mikrogL-1 (cx-MBC) and 0.30 mikrogL-1 (cx-MBC-OH), respectively. A temporal trend of the internal exposure to 4-MBC was clearly noticeable. The metabolite cx-MBC was frequently quantifiable at the beginning of the period: in 70% of the samples in 1995, and 56% in 2005. After 2005, urinary concentrations and detection rates of cx-MBC dropped to reach very low levels. In 2015 and 2019, the detection rate was only 2% and 0%, respectively. A similar trend was observed for cx-MBC-OH, though overall, this metabolite was detected less often and at lower concentration levels than cx-MBC. Nowadays, measurable levels of urinary 4-MBC metabolites are an extremely rare occurrence in Germany. These trends are consistent with the history of 4-MBC use by the cosmetic industry. The highest measured individual concentration of 16.20 mikrogL-1 (in a sample of the year 2005) was still more than 30 times below the health-based guidance value (HBM-I). An investigation of the ratios between both metabolites uncovered several features of the 4-MBC metabolism which have been essentially overlooked until now. In particular, stereochemical aspects should be explored in future studies. As urine was collected in autumn/winter in Northwestern Germany, the 4-MBC metabolites measured prob ably do not arise from sunscreen products in a narrow sense. They rather may reveal the use of other skin care products containing 4-MBC for UV protection as an added feature. © 2023 Elsevier