Sure, but a single particle of that drop when ingested may cause cancer (because there's no thin film of aluminium inside of your body), the entire oceanic eco-system is one extremely complex filtering system for water - and a whole bunch of people get a substantial part of their diet from the sea.

Also, from a cursory search I found this. Quote:

Accumulations of organic tritium into the mussel tissues from tritiated-phytoplankton demonstrate an environmentally relevant transfer pathway of tritium even when water-concentrations are reduced, adding weight to the assertion that organically bound tritium acts as a persistent organic pollutant. The persistence, potential for biomagnification and the increased toxicity of organic tritium increases the potential impact on the environment following a release of HTO; current legislation does not adequately take into account the nature of organic forms of tritium and therefore may be underestimating accumulation and toxic effect of tritium in the environment.

There's a bunch more in the related articles below.

One particle of radiation is very different than a bullet.