Abstract
We measured historical trends of dioxins and agrochemicals (DDTs, PCP and CNP) in five old Rice straws from tatami mats.
The measurement revealed that straw collected in 2000 contained DDTs and PCP The dioxin concentration corresponded to the amounts of PCP and CNP application. The highest total dioxin concentration and TEQ in straws were noted in the 1970 sample, 4300 pg/gdw and 6.1 pgTEQ/gdw respectively.
The source apportioning of PCDD/Fs in rice straws was analyzed by principal component analysis (PCA), correspondence analysis (CA), and multiple regression analysis (MRA) . PCA showed that the main sources of PCDD/Fs in straws were PCP CNP, and combustion (atmospheric deposition) . CA revealed the historical trend of the source, the possibility of an unknown source and the exposure pathway. MRA showed that the main source of PCDD/Fs TEQ was the combustion.
Finally, we estimated the contribution of PCDD/Fs in straws to dairy products (milk, cheese, and butter) and beef from the 1970s to 2000 in Japan. The estimation indicated that it did not contribute much to the remarkable decrease of TDI via dairy products and meat/eggs from the 1970s.
