Recently, it has been pointed out that fertilizer application beyond optimum level should cause heavy metal accumulation in agricultural soil. In this study, we analyzed concentrations of some heavy metals: chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), arsenic (As), cadmium (Cd) and lead (Pb), in greenhouse soils sampled from farmers’ field and neighboring non-cultivated field in southern Kyushu in Japan. A possibility of heavy metal accumulation in the soils was investigated by comparing both soils. The heavy metal concentrations in an acid-labile fraction of the greenhouse soils ranged 18.5-190 mg/kg (Cr), 304-952 mg/kg (Mn), 10.1-36.8 mg/kg (Fe), 2.32-13.6 mg/kg (Co), 7.80-24.7 mg/kg (Ni), 19.8-71.4 mg/kg (Cu), 73.1-250 mg/kg (Zn), 4.40-22.7 mg/kg (Ga), 18.1-74.5 mg/kg (As), 0.0824-0.438 mg/kg (Cd) and 6.79-43.1 mg/kg (Pb), respectively. The concentrations of Cr, Mn, Ni, Cu, Zn and Cd in the greenhouse soils were higher than those in the neighboring non-cultivated soils, which indicates that these six elements have accumulated in the greenhouse soils. In particular, concentrations in the acid-labile Cu, Zn and Cd showed a significant and positive correlation with total concentration of phosphorus in the soils. These correlations suggest that Cr, Cu, Zn and Cd should be derived from phosphate fertilizer which is the major source of phosphorus nutrient for greenhouse culture. The concentration of water-soluble Cr, Mn, Ni, Cu, Zn and Cd also elevated in the most of greenhouse soils, suggesting an increased risk of the element uptake by crops.
Recently, many cases of contact dermatitis due to isothiazolinone preservatives in several types of household products used for cooling the body have been reported. As a result, the concentrations of isothiazolinone preservatives in these products were investigated. However, concentrations of isothiazolinone preservatives in other types of household products have not been studied adequately. In this study, 19 preservatives (including isothiazolinones) in 32 wet tissue products were investigated because these products come in direct contact with the skin. 2-Methyl-4-isothiazolin-3-one (MI), 5-chloro-2-methyl-4-isothiazolin-3-one (CMI), and benzisothiazolin-3-one (BIT) were detected in 19 samples (0.46-48µg/g-wet), 17 samples (trace amount [tr.]-52 µg/g-wet), and one sample (67 µg/g-wet), respectively. Five types of parabens were detected in 21 samples (tr.-834µg/g-wet). 2-Bromo-2-nitropropane-1,3-diol (Bronopol), 3-iodo-2-propynyl N-butylcarbamate (IPBC), and phenoxyethanol were detected in 12 samples (4.7-254 µg/g-wet), 11 samples (tr.-62µg/g-wet),and 4 samples (65-1159 µg/g-wet), respectively. The concentration levels of isothiazolinone preservatives detected in this study perhaps induce allergic contact dermatitis in patients who are already sensitive to these preservatives. However, only 3 products described the use of isothiazolinone preservatives and a cautionary note about the possibility of contact dermatitis due to isothiazolinone preservatives was not provided. We also found that preservatives detected in the samples were different from those indicated on the product (in some cases, name of preservatives were not indicated at all). The use of such products may expose consumers to the risk of contact dermatitis; moreover, when contact dermatitis occurs, the identification of the substance that causes it may be delayed. Therefore, it is desirable that manufacturers provide information about the components of wet tissue products on the product labels.