Health effects of environmental and occupational exposures in children of Pakistan

The increasing trend of immigration from villages and small cities to larger cities resulted in increased social and commercial activities in the metropolitan cities of developing countries, for example, Pakistan. The urbanization resulted in increased vehicular traffic which contributes to outdoor environmental air pollution, in addition to other pollutants including trace elements entering the environment from other sources. Particulate air pollution (PM) has various health effects. The impact can be either short term or long term. The effect on human health depends on the type of pollutant, concentration, duration of exposure, and personal susceptibility. A large body of published scientific evidence shows increased hospital visits, cardiopulmonary morbidity and mortality on days with higher PM. Physiological systems of children being in the growing stage, place them among the most vulnerable populations affected by PM. According to the guidelines of WHO the annual permitted value of PM below 2.5 and 10 µm aerodynamic diameter (PM2.5 and PM10) is 10 and 20 µg/m3, respectively. Unlike the developed world where the legislation has already been made and implemented to regulate PM, developing countries stand behind. In Pakistan, though the legislation is present in its preliminary form, the authorities are not able to implement it fully. As a result, the environmental pollution is high in mega-cities like Lahore, where PM10 has been reported >300 µg/m3. Child labour is prevailingextensively in Asia and the Pacific (with an estimated 127.3 million children at work). In Pakistan, the National Child Labor survey conducted in 1996 by the Federal Bureau of Statistics, reported 3.3 million of the40 million children (in the 5-14 years age group) to be economically active on a full-time basis. Epidemiologic studies and research on young workers suggest that children have higher health risks than adults when exposed to hazardous working environments. Moreover, several potential adverse health impacts of occupational exposures need to be studied in children. Few studies have investigated health consequences of child labour. The aim of the present research was a) to study the health effects of outdoor PM among apparently healthy schoolchildren, b) to estimate the urinary concentrations of metals in schoolchildren and working children, and c) to study the health effects of occupational exposures among children employed in selected industries, that is, brick kiln, carpetweaving and surgical instruments manufacturing.In chapter 2, we report the exposure to PM2.5 and PM10 among schoolchildren from a low and ahigh pollution area in Lahore, Pakistan. Exposure assessment was done by measuring PM with a portable laser operated mass analyzer. Blood pressure (BP) was measured with an automated instrument. We found that children living and attending school in an area of very high traffic-related air pollution had a substantially higher systolic (7.6 mmHg) and diastolic (4.5 mmHg) BP compared with children living in an area with lower PM. In chapter 3, we report the relation between exposure to low level environmental cadmium (Cd) exposure and urinary excretion of calcium (Ca)and deoxypyridinoline (DPD), a marker of bone resorption. Exposure assessment was carried out by estimation of urinary Cd by inductively-coupled plasma mass spectrometry (ICP-MS) and DPD by enzyme linked immunosorbent assay (ELISA). We found a consistent association between biomarkers of bone resorption and bone demineralization and Cd exposure in 10-year old children. For each doubling in urinary Cd excretion, bone resorption estimated by DPD increased by 1.72 nmol/mmol creatinine.In chapter 4, we report the work-related exposure to metals among children working in surgical instruments manufacturing units. Estimation of 20 metals was done in spot urine samples by ICP-MS. 8-Hydroxydeoxyguanosine (8-OHdG), a marker of DNA damage was measured by ELISA. Among child workers, this biomonitoring study revealed a substantial exposure to several metals, especially chromium (Cr) and nickel (Ni), which are established carcinogens. Concentrations of Ni were associated with evidence of increased oxidative DNA damage.In chapter 5, we report the respiratory health and metal exposure among schoolchildren and working children from brick kilnand carpet weaving industries. Exposure assessment was done by estimating metals in spot urine by ICP-MS. Respiratory health was assessed by performing spirometry and measuring fractional exhaled nitric oxide (FeNO). We found a high prevalence of respiratory symptoms in children exposedto urban air pollution and in working children, as well as evidence of a high exposure to several toxic metals. The concentrations of urinary As are in the order of those found in other Asian regions with high environmental exposure to As. The sources and pathways of exposure and the health significance of these findings need to be further investigated.Among the selected populations of schoolchildren and children working ineither brick kiln, carpet weaving or surgical industry, we estimated the environmental and occupational exposures. We found a) significantly increased systolic and diastolic blood pressure among schoolchildren from high pollution urban area, b) association of markers of bone resorption (DPD) and bone demineralization (Ca) and Cd exposure, c) high exposures to Cr and Ni among children working in surgical industry and the association of Ni with 8-OHdG, and d) high prevalence of respiratory symptoms in schoolchildren and working children as well as high levels of urinary As.Although our cross-sectional findings have limitations, they haveidentified and confirmed significant health threats among children in Pakistan. Hence, general and specific preventive and control measures should be implemented.status: publishe

Adverse health effects of child labor : high exposure to chronium and oxidative DNA damage in children manufacturing surgical instruments.

BACKGROUND: A considerable part of the worldwide production of surgical instruments takes place in Sialkot, Pakistan. Many children work in hazardous conditions in this industry. OBJECTIVE: We investigated exposure to metals and possible health effects among children working in surgical instruments manufacturing units compared with schoolchildren from the same city. METHODS: In a cross-sectional study we studied a convenience sample of 104 male children (10-14 years of age) working in surgical instruments manufacturing units and 75 male children of similar age from a school in Sialkot, Pakistan. A respiratory questionnaire was administered, spirometry was performed, and blood pressure was measured. In a spot urine sample, concentrations of metals were measured by inductively coupled plasma mass spectrometry and 8-hydroxydeoxyguanosine (8OHdG, reflecting oxidative DNA damage) by ELISA. RESULTS: The working children reported more asthma (10% vs. 0%; p = 0.005) and dry cough at night (36% vs. 20%; p = 0.02) than did the schoolchildren, but there were no significant differences in pulmonary function or blood pressure. The urinary concentration of chromium was 35 times higher in working children [geometric mean, 23.0 µg/L; 25th-75th percentile, 8.38-58.6] than in schoolchildren [0.66 µg/L; 0.38-1.09)], and largely in excess of the occupational Biological Exposure Index for adult workers (25 µg/L). Urinary 8-OHdG concentrations were not significantly higher in working children than in schoolchildren (19.3 vs. 17.6 µg/g creatinine, p = 0.4), but were significantly correlated with urinary nickel (r = 0.41; p < 0.0001) and with a composite index of metal exposure (r = 0.46; p < 0.0001). CONCLUSIONS: Children working in the surgical instruments manufacturing industry had substantial exposure to several metals, especially chromium and nickel, which are established carcinogens. Exposure to nickel was associated with evidence of increased oxidative DNA damage

Bone resorption and environmental exposure to cadmium in children: a cross - sectional study

<p>Abstract</p> <p>Background</p> <p>Exposure to cadmium has been associated with osteoporosis and fracture risk in women and elderly, but studies in children are lacking. In the present study we investigate the association between markers of bone demineralization [urinary calcium (Ca) and deoxypyridinoline (DPD) excretion] and urinary cadmium (Cd) excretion (as an index of lifetime body burden).</p> <p>Methods</p> <p>155 schoolchildren from 2 elementary schools in Lahore, Pakistan were included. Urinary Cd was measured as an index of lifetime exposure. We assessed the multivariate-adjusted association of exposure with markers of bone resorption, urinary DPD as well as with Ca excretion.</p> <p>Results</p> <p>Urinary Cd averaged 0.50 nmol/mmol creatinine and was not influenced by age, height, weight and socio-economic status (SES). Independent of gender, age, height, weight and SES a doubling of urinary Cd was associated with a 1.72 times (p < 0.0001) increase in urinary DPD and, a 1.21 times (p = 0.02) increase in urinary Ca. Additional adjustment for urinary Ca revealed still significant associations between urinary Cd and urinary DPD. The shape of the association was linear without evidence of a threshold.</p> <p>Conclusions</p> <p>Even in young children, low-level environmental exposure to cadmium is associated with evidence of bone resorption, suggesting a direct osteotoxic effect with increased calciuria. These findings might have clinical relevance at older age.</p

Metal exposure in schoolchildren and working children. A urinary biomonitoring study from Lahore, Pakistan

In order to document the exposure to trace metals among urban schoolchildren and rural working children, we measured the urinary concentrations of metals in schoolchildren from two areas of differing traffic intensity in Lahore, and in children working in carpet weaving or the brick industry outside Lahore. In a cross-sectional design, we recruited a convenience sample of 339 children aged 8-12 years (mean age 9.9 y, SD 1.4; 47% girls) from two elementary schools in Lahore - one situated in a high air pollution area (n=100) and one situated in an area with lower air pollution (n=79) - and from the carpet weaving industry (n=80) and brick industry (n=80). A spot urine sample was collected and concentrations of 20 metals and metalloids were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Samples of drinking water were similarly analyzed. In general, the urinary concentrations of several toxic metals (including Cr, Mn, As, Mo, Cd, Pb, U) were higher than international reference values. Concentrations of As were especially elevated in children working in the brick making industry [geometric mean (GM) 118μg/L], but they were also high among urban schoolchildren (GM 68μg/L and 56μg/L). Lead (Pb) was higher in urine from schoolchildren in the high air pollution area (GM 11μg/L) than in those from the lower pollution area (GM 5.3μg/L). Uranium (U) was high in both carpet weavers (GM 0.28μg/L) and brick kiln workers (GM 0.45μg/L). Concentrations of As, Pb, and U in drinking water corresponded well with urinary concentrations of metals. This descriptive study provides evidence for a high exposure to several toxic metals in this area of Pakistan. The concentrations of urinary As are in the order of those found in other regions of the world with high environmental exposure to As. The sources and pathways of exposure and the health significance of these findings need to be further investigated

Subclinical responses in healthy cyclists briefly exposed to traffic-related air pollution: an intervention study

<p>Abstract</p> <p>Background</p> <p>Numerous epidemiological studies have demonstrated adverse health effects of a sedentary life style, on the one hand, and of acute and chronic exposure to traffic-related air pollution, on the other. Because physical exercise augments the amount of inhaled pollutants, it is not clear whether cycling to work in a polluted urban environment should be encouraged or not. To address this conundrum we investigated if a bicycle journey along a busy commuting road would induce changes in biomarkers of pulmonary and systematic inflammation in a group of healthy subjects.</p> <p>Methods</p> <p>38 volunteers (mean age: 43 ± 8.6 years, 26% women) cycled for about 20 minutes in real traffic near a major bypass road (road test; mean UFP exposure: 28,867 particles per cm³) in Antwerp and in a laboratory with filtered air (clean room; mean UFP exposure: 496 particles per cm³). The exercise intensity (heart rate) and duration of cycling were similar for each volunteer in both experiments. Exhaled nitric oxide (NO), plasma interleukin-6 (IL-6), platelet function, Clara cell protein in serum and blood cell counts were measured before and 30 minutes after exercise.</p> <p>Results</p> <p>Percentage of blood neutrophils increased significantly more (p = 0.004) after exercise in the road test (3.9%; 95% CI: 1.5 to 6.2%; p = 0.003) than after exercise in the clean room (0.2%; 95% CI: -1.8 to 2.2%, p = 0.83). The pre/post-cycling changes in exhaled NO, plasma IL-6, platelet function, serum levels of Clara cell protein and number of total blood leukocytes did not differ significantly between the two scenarios.</p> <p>Conclusions</p> <p>Traffic-related exposure to particles during exercise caused a small increase in the distribution of inflammatory blood cells in healthy subjects. The health significance of this isolated change is unclear.</p