The [15N]methacetin liver function test characterizes multicomponent exposure of children in industrially polluted regions

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Volatile organic compounds and formaldehyde as explaining factors for sensory irritation in office environments

This study's database comprised results of volatile organic compound (VOC) measurements from 176 office buildings. In 23 of the 176 buildings, formaldehyde measurements were also conducted. It was suspected that the buildings had indoor air problems, but a walk-through inspection did not reveal any clear, abnormal contaminant sources. The 50 most abundant VOCs and their concentrations in 520 air samples were analyzed. The irritation potency was estimated for 33 out of the 50 common VOCs and their mixtures, as well as for formaldehyde. This information was used to calculate the recommended indoor air levels (RILs) for the VOCs. The RILs were considerably higher than the measured mean indoor air concentrations in the buildings. However, the RIL for formaldehyde was exceeded in most of the 23 buildings studied. According to the evaluation of irritation potency, formaldehyde was a more likely cause of sensory irritation than the mixture of common nonreactive VOCs at the concentrations that occurred in the buildings without abnormal indoor sources. Furthermore, environmental symptoms of office workers were characterized in 20 office buildings (including the database of 176 office buildings) with the aid of an indoor air questionnaire. The most frequent symptoms related to the indoor environment were involved the upper respiratory tract. However, no relationship could be shown between the reported symptoms and the occurrence of VOC and formaldehyde concentrations in these buildings. Generally, the study results indicated that formaldehyde was the more likely agent causing sensory irritation than the mixture of the common nonreactive VOCs at the concentrations occurring in the buildings without abnormal indoor sources.

13C- mithacetin breath test for assessment of liver functional capacity

AIM: To investigate the clinical significance of ¹³C-mithacetin breath tests for assessment and the classification of liver functional capacity.

METHODS: Twelve healthy volunteers served as a control group. Patients (test group) with different kinds of liver diseases were divided into 4 sub-groups: compensatory period (n = 4), Child-Pugh classification A, B, C (n = 12, 12, 16, respectively). Patients in both groups were examined for liver function by a biochemical test after orally taking ¹³C-mithacetin (75 mg). Gas breathed out was collected at 9 different time within 120 min. The samples were analyzed with mass spectrograph to obtain DOB, MV and CUM curves and CUM120 value.

RESULTS: Biochemical index such as ALB and pre-albumin (PA) in patients of test group (Child-Pugh A, B and C) were significantly decreased as compared with those in patients of control group (ALB: 33.1 ± 3.1, 29.3 ± 6.5, 27.9 ± 5.0 vs 36.6 ± 4.7; PA: 119.7 ± 51.0, 104.3 ± 21.1, 77.4 ± 32.9 vs 176.4 ± 68.2; P < 0.05). The classifications of liver capacity significantly related to the values of ALB and PA (P < 0.05). Peak values of DOB and MV curves negatively related to the peak time in the test group (DOB: r = -0.48, P < 0.01; MV: r = -0.57, P < 0.01). Peak values of DOB, MV and CUM decreased with the development of liver dysfunction. Significant difference existed between the test group (Child-Pugh A, B, and C respectively) and control group (DOB: 10.4 ± 3.39, 6.71 ± 3.58, 4.00 ± 1.40 vs 20.93 ± 7.56; MV: 13.12 ± 9.51, 11.61 ± 8.02, 10.20 ± 4.99 vs 29.53; CUM: 18.09 ± 18.09, 16.60 ± 16.60, 15.82 ± 15.82 vs 30.67 ± 2.85; P < 0.05 repectively). CUM120 values in patients of the test group (Child-Pugh A, B, and C) significantly decreased as compared with those in patients of control group (63.61 ± 36.67, 59.32 ± 24.73, 52.62 ± 23.92 vs 109.45 ± 10.26; P < 0.05), but no significant decrease appeared among sub-groups.

CONCLUSION: ¹³C-mithacetin breath test is a safe, effective method in assessment and classification of liver capacity. Mean peak values of DOB, MV and CUM curves and CUM120 value decrease with the development of liver dysfunctions. Peak values are more clinically significant than peak time.

Noninvasive assessment of liver detoxification capacity of children, observed in children from heavily polluted industrial and clean control areas, together with assessments of air pollution and chloro-organic body burden

The liver is an important target organ in exposure to foreign substances or their metabolites. Early changes in the metabolic capacity of the liver may be a first sign of the effect of an exposure and an indication of an early (pre)pathological process. For the noninvasive testing of this metabolic capacity, a special diagnostic tool has been developed and demonstrated under real exposure conditions. The main questions investigated were (1) whether the liver detoxification capacity of children is affected by long-term low exposure in a highly polluted area and (2) to what extent redevelopment in once heavily polluted industrial areas contributes to improvement in the health measured in the children from the changed detoxification capacity. Kindergarten children from a heavily polluted industrial area and a control area were observed over a prolonged period during redevelopment of the industrial area. The liver's detoxification capacity was assessed with a stable-isotope-based diagnostic test, the [(15)N]methacetin test. In addition, the region-specific external exposure (indicator components were chlorinated compounds) and internal load were measured. The difference in the children's internal load between the exposed and control groups reflected the differences in exposure (exposed children had an internal load 2.3 times greater than that of the control children). The exposed children showed a 6% lower liver detoxification capacity. A reduction in pollution by about 70% as a result of remediation was reflected in improved liver detoxification capacity, and the difference between the polluted and control areas was no longer significant. Prolonged exposure to low concentrations of xenobiotics can disturb hepatic functioning. The proposed test can be used as a tool to determine the effects of multicomponent exposure and is well suited for bioeffect monitoring.

Detecting exposure-dependent changes of liver detoxification capacity of children in a formerly high-loaded industrial area with a 15N-labelled diagnostic tool

The effect of remediation activities in formerly high-loaded industrial areas is measured conventionally in terms of decreased toxic loads. It is more difficult to investigate the effect on physiological parameters of the people living there. A non-invasive 15N-based organ function test, the [15N]methacetin urine test, was adapted to environmental-medical purposes for the detection of small deviations from the norm-range hepatic detoxification capacity. Parallel to the measurement of region-specific external exposure (especially by tri- and tetrachloro ethylene) and of the corresponding internal load (urinary trichloro acetic acid), the hepatic mono oxygenation capacity was determined. The study cohort consisted of 35 kindergarten children who were 3.3+/-0.5 years old at the beginning of the study. They lived in a high-polluted industrial village (n = 23) and in a non-polluted control village close by (n = 12), respectively. Children living in the polluted area were exposed a 2.3 times higher load and showed detoxification capacities 6% lower than the children in the control area. Improvement of the environmental situation led to exposure data decreasing by 70%, which is also reflected in smaller internal load and improved liver detoxification of the children in the polluted area. Then, between loaded and control area the mean hepatic detoxification was no longer significantly different (0.6%). The study shows that chronic low-dose exposure can disturb a hepatic function and that thereafter the capacity is recovered quickly in children. The stable isotope-based test is suited to characterize a health effect of multicomponent exposure by bioeffect monitoring within the framework of screening and testing the remediation efficiency.

Seasonal cycle of VOCs in apartments

To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996-99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation.