Final answer:
Complex phenols for disinfection can cause skin irritation.
Step-by-step explanation:
One reason for taking precautions when using complex phenols for disinfection is that they can cause skin irritation. Phenols, such as phenol and hexachlorophene, are toxic to humans and can cause severe burns when applied to the skin. Therefore, it is important to handle these disinfectants with care and take necessary precautions, such as wearing gloves and protective clothing, to avoid skin irritation.