In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.

Example input: Antisperm antibodies were assessed in the serum samples of 73 men unable to ejaculate naturally and on the sperm cells of 13 of these men.
Example output: serum
Example explanation: Serum is a substance of the organism and needs to be tagged.
Q:  Among adolescent boys in Chapaevsk , Russia , higher serum levels of sum of dioxin - like compounds and sum of dioxin TEQs were positively associated with increased age , consumption of fish , local meats other than chicken , and inversely with weeks of gestation .
A:
serum