Temporal transition trends of cord blood lead levels in various human development index countries and in the Taipei metropolitan area

Since low-level lead exposure is still of concern for neonates, it is worth further characterizing the temporal transition trends of cord blood lead levels (CBLLs) globally and locally in Taipei, Taiwan, after the cessation of leaded gasoline use. A literature review on CBLLs around the world was performed by searching three databanks, i.e., PubMed, Google Scholar and Web of Science, with the search keywords cord blood combined with lead or Pb for studies published from 1975 to May 2021. In total, 66 articles were included. Linear regressions for the reciprocal of sample size weighed CBLLs against calendar year presented a high r2 value (0.722) for the very high Human Development Index (HDI) countries and a moderate r2 value (0.308) for the combined high and medium HDI countries. The predicted CBLLs in 2030 and 2040 were 6.92 (95% CI: 6.02-7.81) & mu;g/L and 5.85 (95% CI: 5.04-6.66) & mu;g/L, respectively, for the very high HDI countries and 13.10 (95% CI: 7.12-19.09) & mu;g/L and 10.63 (95% CI: 5.37-15.89) & mu;g/L, respectively, for the combined high and medium HDI countries. To characterize the CBLL transitions in the Great Taipei metropolitan area, data from five studies conducted from 1985 to 2018 were employed. Although the results of the early four studies indicated that the Great Taipei metropolitan area did not reach the pace in CBLL reduction among the very high HDI countries, the CBLLs of the latest study during 2016-2018 were pretty low (8.1 & PLUSMN; 4.5 & mu;g/L), approximately 3 years in advance of the very high HDI countries as one group to reach this low CBLL. In conclusion, further effective reduction in environmental lead exposure is challenging and must be based on the efforts from the aspects reflected by the HDI index compositions, i.e., economics, education and health, mostly implying health disparity and inequality.

Automated summary

Although the cord blood lead levels (CBLLs) in the Great Taipei metropolitan area did not reach the pace of reduction compared to very high HDI countries in the early years, the latest study showed that CBLLs were significantly lower (8.1 ± 4.5 μg/L) during 2016-2018, approximately 3 years ahead of the very high HDI countries as a whole. This suggests that further efforts to reduce environmental lead exposure are challenging and should be based on the aspects reflected by the HDI index, such as economics, education, and health.