Hair nicotine/cotinine concentrations as a method of monitoring exposure to tobacco smoke among infants and adults.

In this pilot study, we examined the validity and usefulness of hair nicotine-cotinine evaluation as a biomarker of monitoring exposure to tobacco. Head hair samples were collected from 22 infants (<2 years of age) and 44 adults with different exposures to tobacco (through either active or passive smoking) and analyzed by liquid chromatography-mass spectrometry (LC-MS) for nicotine and cotinine. Hair samples were divided into three groups, infants, passive smoker adults and active smoker adults, and into eight subgroups according to the degree of exposure. The limit of quantification (LOQ) was 0.1 ng/mg for nicotine and 0.05 ng/mg for cotinine. Mean recovery was 69.15% for nicotine and 72.08% for cotinine. The within- and between-day precision for cotinine and nicotine was calculated at different concentrations. Moreover, hair nicotine and cotinine concentrations were highly correlated among adult active smokers (R (2) = 0.710, p < 0.001), among adult nonsmokers exposed to secondhand smoke (SHS; R (2) = 0.729, p < 0.001) and among infants (R (2) = 0.538, p = 0.01). Among the infants exposed to SHS from both parents the noted correlations were even stronger (R (2) = 0.835, p = 0.02). The above results identify the use of hair samples as an effective method for assessing exposure to tobacco, with a high association between nicotine and cotinine especially among infants heavily exposed to SHS.

Determination of dialkyl phosphates in human hair for the biomonitoring of exposure to organophosphate pesticides.

A new, simple, fast and sensitive method that enables the measurement of four dialkyl phosphates (DAPs) in human head hair is presented in the current study. The dialkyl phosphates, dimethyl phosphate (DMP), diethyl phosphate (DEP), diethyl thiophosphate (DETP) and diethyl dithiophosphate (DEDTP) are non-selective metabolites of the organophosphate pesticides (OPs). The extraction of DAPs from hair matrix was achieved by one step methanolic extraction. Head hair samples from general population and population occupationally exposed to OPs were analysed using gas chromatography-mass spectrometry (GC-MS) after derivatization with pentafluorobenzylbromide. The recovery of the target compounds was estimated at 84.3% for DMP, 116.1% for DEP, 109.0% for DETP and 91.5% for DEDTP. The limit of quantitation (LOQ) and detection (LOD) was 20 and 6 pg/mg for DMP, 10 and 5 pg/mg for DEP and DETP and 5 and 3 pg/mg for DEDTP, respectively. With-run and between-run precision as well as accuracy was estimated. The percentage of positive hair samples for DMP, DEP, DETP and DEDTP for the group of general population was 63.0%, 96.3%, 66.7%, and 70.4% respectively. The samples from the group with occupational exposure were positive for all dialkyl phosphates analysed. The median concentrations for DMP were 165.0 and 181.7 pg/mg, for DEP were 51.2 and 812.9 pg/mg, for DETP were 54.0 and 660.1 pg/mg, and for DEDTP were 40.0 and 60.6 pg/mg for the general population group and the group with occupational exposure respectively. Significant differences in the levels of the total dialkyl phosphates amongst exposed and not exposed groups were observed (p<0.001). More specifically, the total ethyl phosphate (DEPs) and DAPs median concentrations were 119.5 and 301.5 pg/mg for the general population group and 1498.8 and 1694.4 pg/mg for the group with occupational exposure.