| Substance | Sweat (1h) | Urine (24h) |
| --------- | ---------- | ----------- |
| Urea | ~0.3–1.2 g | ~20–30 g |
| Lead | ~5–50 µg | ~10–50 µg |
| Arsenic | ~10–60 µg | ~20–200 µg |
So, I wouldn't dismiss based on current knowledge, and besides, this has no practical importance even if so, as sauna has the number of other measurable benefits.