Because
of its irritating effect on humans,the use of phenol as a general antiseptic
has been largely discontinued.
由于苯酚对人体带有刺激性作用,它基本上已不再被当作常用的防腐剂了.
Because of its irritating effect on humans,原因状语
其中irritating作定语,修饰effect,
the use of phenol as a general antiseptic has been largely discontinued.
主语：The use of phenol as a general antiseptic (其中of phenol as a general antiseptic做定语,修饰主语）
谓语：has been
表语：largely discontinued （其中largely副词做状语,修饰discontinued)