阳离子交换树脂在使用过程中，因为遭到有害杂质（如铁化物、有机物等）的污染，就会发作树脂“中毒”事端。发作铁“中毒”的树脂，从外观上看，色彩由通明的黄色（阳树脂）或乳白色（阴树脂）显着变深，严重者乃至呈黑色。
In the process of using cation exchange resin, because of the contamination of harmful impurities (such as ferrite, organic matter, etc.), resin "poisoning" will occur. From the appearance, the colour of the resin with iron poisoning has changed from bright yellow (positive resin) or milky white (negative resin) to dark, even black.
形成树脂铁“中毒”的原因主要有4方面：①水源是含铁量高的地下水或被铁污染的地表水；②进水管道或交换器内部被腐蚀产生了铁化物；③再生剂中含有铁杂质；④水中含有大分子有机物。
There are four main reasons for the "poisoning" of resin iron: water source is groundwater with high iron content or surface water polluted by iron; iron carbide is produced by corrosion in intake pipeline or exchanger; iron impurity is contained in regenerant; and macromolecule organic matter is contained in water.