| Normala | Optimalb | Acceptablec | Problematicc | Potentially Toxicb |
---|---|---|---|---|---|
Unilateral | Â | Â | Â | Â | Â |
 • Co | <1.5 μg/L | <4.0 μg/L | 4–10 μg/L | 10–20 μg/L | >20 μg/L |
 • Cr | <1.5 μg/L | <4.6 μg/L | 4.6–10 μg/L | 10–20 μg/L | >20 μg/L |
Bilateral | Â | Â | Â | Â | Â |
 • Co | <1.5 μg/L | <5.0 μg/L | 5–10 μg/L | 10–20 μg/L | >20 μg/L |
 • Cr | <1.5 μg/L | <7.4 μg/L | 7.4–10 μg/L | 10–20 μg/L | >20 μg/L |