Open Access 22.08.2018 | Original Article
Metabolites of the alkyl pyrrolidone solvents NMP and NEP in 24-h urine samples of the German Environmental Specimen Bank from 1991 to 2014
Erschienen in: International Archives of Occupational and Environmental Health | Ausgabe 8/2018
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Purpose
The aim of this study was to get a first overview of the exposure to
the solvents and reproductive toxicants N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP) in Germany. NMP and NEP metabolite
concentrations were determined in 540 24-h urine samples of the German
Environmental Specimen Bank collected from 1991 to 2014. With these data we were
able to investigate NMP/NEP exposures over time and to evaluate associated
risks.
Methods
NMP metabolites 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methylsuccinimide (2-HMSI) and NEP metabolites
5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP)
and 2-hydroxy-N-ethylsuccinimide (2-HESI)
were determined by stable isotope dilution analysis using solid phase extraction
followed by derivatization (silylation) and GC–EI–MS/MS.
Results
We were able to quantify 5-HNMP and 2-HMSI in 98.0 and 99.6% and
5-HNEP and 2-HESI in 34.8 and 75.7% of the samples. Metabolite concentrations
were rather steady over the timeframe investigated, even for NEP which has been
introduced as an NMP substitute only in the last decade. Calculated median daily
intakes in 2014 were 2.7 µg/kg bw/day for NMP and 1.1 µg/kg bw/day for NEP. For
the combined risk assessment of NMP and NEP exposure, the hazard index based on
the human biomonitoring assessment I values (HBM I values) was less than
0.1.
Conclusions
Based on the investigated subpopulation of the German population,
individual and combined NMP and NEP exposures were within acceptable ranges in
the investigated timeframe. Sources of NEP exposure in the 90s and 00s remain
elusive.
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