Effects of fine particulate matter bound heavy metals on intentional self-harm deaths in Guangzhou, China, insight from core chemical constituents.

Fine particulate matter (PM_2.5) is one of the major threats to human health, and may partly responsible for intentional self-harm deaths, while the limited results seemed contradictory. Further analysis on PM_2.5 constituents may provide more reliable evidence. Heavy metals are crucial toxic components of PM_2.5 that may induce suicide behavior. What role do PM_2.5-bound heavy metals play in a threat to intentional self-harm death is still unclear. Two-year data of daily PM_2.5-bound heavy metals (including metalloids) and daily intentional self-harm deaths were collected in Guangzhou. Bayesian kernel machine regression, weighted quantile sum, and quantile-based g-computation models were employed to depict the relationships between heavy metals and intentional self-harm deaths. The number of intentional self-harm deaths was 217 and 283 for 2015 and 2016, respectively. A positive correlation was found between the combined effect of the 13 heavy metals and intentional self-harm deaths. Nickel, cadmium, and iron were the primary contributors to this positive correlation. Heavy metal components play significant roles in PM_2.5-related intentional self-harm deaths, and targeted source control measures are warranted to protect residents from suicide.