Isotopic ratio based source apportionment of children's blood lead around coking plant area

Abstract

Lead exposure in the environment is a major hazard affecting human health, particularly for children. The blood lead levels in the local children living around the largest coking area in China were measured, and the source of blood lead and the main pathways of lead exposure were investigated based on lead isotopic ratios ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) in blood and in a variety of media, including food, airborne particulate matter, soil, dust and drinking water. The children's blood lead level was 5.25 (1.59 to 34.36 as range) μg dL −1 , lower than the threshold in the current criteria of China defined by the US Centers for Disease Control (10 μg dL −1 ). The isotopic ratios in the blood were 2.111 ± 0.018 for 208 Pb/ 206 Pb and 0.864 ± 0.005 for 207 Pb/ 206 Pb, similar to those of vegetables, wheat, drinking water, airborne particulate matter, but different from those of vehicle emission and soil/dust, suggesting that the formers were the main pathway of lead exposure among the children. The exposure pathway analysis based on the isotopic ratios and the human health risk assessment showed that dietary intake of food and drinking water contributed 93.67% of total exposed lead. The study further indicated that the coal used in the coking plant is the dominant pollution source of lead in children's blood.

Levels and source apportionment of children's lead exposure: Could urinary lead be used to identify the levels and sources of children's lead pollution?

“…1(b) and 2). This is another indication that, food and tap water via ingestion and particulate matter via both inhalation and settled dust are the two main lead exposure pathways for children living around the two sites, which could be confirmed by the analysis of exposure pathways in our previous study (Cao et al, 2014b). This also supports the previous assumption that urinary lead indicates short-term exposure and can be used to assess rapid changes in lead exposure, particularly that from the environment through diet or inhalation (Gulson et al, 1998b).…”

“…The lead concentrations and the pollution source in children's blood in the coking site were assessed in our previous study (Cao et al, 2014b). For the battery site, as shown in Table 3, the lead concentrations in soil/dust were higher than the local background value (75.87 mg g À1 ), and the lead concentrations in duplicate food were greater than the threshold values (0.1e0.3 mg kg À1 for foodspecific).…”

“…Coking area (Cao et al, 2014b) Lead-acid battery area in the urine of children may originate from coal combustion. This assumption was supported by the distribution of LIRs shown in Fig.…”

“…The pollution source and exposure pathways of children's blood lead for the coking site were assessed based on the blood LIR analysis in our previous study (Cao et al, 2014b), which illustrated that lead contamination of children was attributable mainly to coal combustion. For the children in the battery area, most of the data points on the plot of 208 Pb/ 206 Pb versus 207 Pb/ 206 Pb ratios shown in Fig.…”

“…After adding two drops of 65% concentrated HNO 3 , a portion of each sample was kept at 4 C prior to concentration analysis. Another part of each sample was prepared for isotope analysis (Cao et al, 2014b).…”