Screening of pesticides in serum, urine and cerebrospinal fluid collected from an urban population in China.

Human exposure to pesticides is a topic of public health concern for decades. Pesticide exposures have been assessed through the analysis of urine or blood matrices, but little is known on the accumulation of these chemicals in cerebrospinal fluid (CSF). CSF plays an important role in maintaining physical and chemical balance of the brain and central nervous system and any perturbation can have adverse effects on health. In this study, we investigated the occurrence of 222 pesticides in CSF from 91 individuals using gas chromatography-tandem mass spectrometry (GC-MS/MS). Measured pesticide concentrations in CSF were compared with those in 100 serum and urine specimens from individuals living in the same urban location. Twenty pesticides were found in CSF, serum and urine, at levels above the limit of detection. Three most frequently detected pesticides in CSF were biphenyl (100%), diphenylamine (75%), and hexachlorobenzene (63%). Median concentrations of biphenyl in CSF, serum and urine were 1.11, 10.6, and 1.10 ng/mL, respectively. Six triazole fungicides were found only in CSF, but not in other matrices. To our knowledge, this is the first study to report pesticide concentrations in CSF in a general urban population.

[Heterogeneous Oxidation of Secondary Organic Tracers of Isoprene and Toluene by Ozone].

For this paper, chamber experiments were carried out to investigate the oxidation of secondary organic tracers of toluene and isoprene by ozone under different conditions (relative humidity, mixing state, etc.) using a relative rate constants approach. The uncertainty of the tracer-based method due to the ozone oxidation of secondary organic tracers was also addressed. The results showed that the effective rate constants of analogue of 2-methyl erythritol (AME) and 2,3-dihydroxy-4-oxopentanoic acid (DHOPA) were (4.60±0.66)×10-19 cm3·(molecule·s)-1and (6.57±0.51)×10-19 cm3·(molecule·s)-1, respectively. Given the instability of the secondary organic tracers caused by the oxidation, the contributions of toluene and isoprene to secondary organic aerosols could be underestimated by 16.5%-44.8% and 18.3%-47.3%, respectively.