Ground water samples were taken from 8 wells at Kitaura area of Gogoshima in Matsuyama City. The sample water was collected every month from June 1978 to January 1979 and some anions contained in them were analyzed in order to examin the characteristics of the ground water.
The concentration of anions in this Island wells were higher 2.5-13 times than that of inland wells. The average concentration of Cl^- is 23 ppm, and this shows that sea water did not permiate into it. The high concentrations of SO₄^2-, NO^-₃-N, and NH⁺₄-N may be caused by chemical manure and compost which are given to the tangerine orchard. 74% of samples analyzed showed the coexistence of NO^-₂-N and NH⁺₄-N. In this area, the flow direction of under groundwater may be 5→1→2, 8→7→2 based on the analysis of concentration correlation matrix and -columner section.

Salithion, an agricultural chemical, was sprayed in persimmon orchards. The exposure of salithion to workers' bodies and the amount of salithion in the blood were measured.
The orchards were situated in the Tataki area of Tanbara-cho, Shuso-gun, Ehime prefecture. Before spraying, the salithion solution was diluted 1, 000 fold.
The amount of salithion exposed to the skin of the sprayers was estimated by the measured amount of salithion on the gloves, socks and filter paper that was put on their underwear. The results were as follows.
1) The mean amount of salithion exposed to the body surface of the sprayers who were protected perfectly was estimated to be 0.54 mg. On the other hand, the exposure to the sprayers protected imperfectly was 8.02 mg. The latter value was 15 times higher than the former, and the difference was statistically significant (p<0.05).
2) The concentration of the salithion in the blood of the sprayers was 11.5±13.8 ppb (M±SD). The correlation coefficient between salithion concentration in the blood and the amount of salithion exposed to the body surface was r = 0.73 (p<0.01).

Inhibitory effect of organophosphorus pesticides on the activity of carboxylesterase (CE), arylarnidase (AAA) and cholinesterase (ChE) in human plasma was investigated. The CE, AAA and ChE activities in human plasma were inhibited by various organophosphorus pesticides. Especially EDDP, BRP, DEP and DDVP showed low I₅₀ values for these enzymes. Generally, the I₅₀ values of CE were lower than those of AAA and ChE for pesticides. The CE activities of DDVP sprayers were significantly reduced after spraying. The mixed pesticides of MEP and IBP increased the inhibitory effect on the CE activity as compared with the individual of the respective pesticides. All of the pesticides investigated in this study showed noncompetitive inhibition to the CE activity in human plasma. The CE and AAA activties were possibly inhibited by -NO₂ radical of MEP stronger than-SCH₃ radical of MPP. The pl₅₀ (-log I₅₀) values of various pesticides on these three enzymes were closely related to each other. The correlation coefficient was over than 0.9.