No, an employer may accept a negative/dilute test result as a negative test. If the employer wants a retest it may do so, however, it must be stated in the employer's policy and the employer must require a retest of all individuals that have a negative/dilute result in the same testing category.
Alcohol affects activity of such neurotransmitters as glutamate, GABA, and dopamine; caffeine blocks the action of the neurotransmitter adenosine. Such changes are studied in the field of psychopharamacology, which concerns the effects of drugs on the mind and brain. This field investigates both recreational drugs such as alcohol, caffeine, marijuana, cocaine, and LSD, and therapeutic drugs such as antidepressants and antipsychotics.
Health and Behavioral Risks of Alcohol and Drug Use The negative physical and mental effects of the use of alcohol and other drugs are well documented. Use of these drugs may cause: blackouts, poisoning, overdose and death; physical and psychological dependence; damage to vital organs such as the brain, heart, and liver; inability to learn and remember information; and psychological problems including depression, psychosis, and severe anxiety.