TABLE 5.
Comparison of fecal (or colon) mercury concentrations between walruses and humans.
| # | Sample | Matrix | Location | Sample size (n) | THg (ng/g dw) Median (range) | MeHg (ng/g dw) Median (range) | %MeHg (of THg) Median (range) | References |
| 1 | Walrus | Fecal | St. Lawrence Island, Alaska, United States | 16 | 200 (72, 650) | 4.7 (0.96, 70) | 2.5 (0.46, 30) | This study |
| Walrus | Colon | St. Lawrence Island, Alaska, United States | 16 | 28 (15, 95) | 7.8 (3.3, 57) | 26 (16, 60) | ||
| 2 | Adult mena,b | Fecal | Japan | 4 4 | 270 (260–290) 190 (120–250) | 41 (15–46) 21 (12–35) | 17 (5.3, 29) 12 (8.4–32) | Ishihara (2000) |
| 3 | Adult men and womena,c | Fecal | Rochester, New York, United States | 8 8 | 160 (95, 390) 170 (33, 600) | 0d (0, 63) 5.9d (0, 80) | 0 (0, 42) 5.9 (0, 23) | Rand et al., 2016 |
| 4 | Adult men and womena | Fecal | Rochester, New York, United States | 33 | 130 (47–270) | 2.8d (0, 54) | 2.3 (0, 71) | Caito et al., 2018 |
| 5 | Pregnant mothers, Late gestatione | Fecal | Greenville, South Carolina, United States | 17 | 30 (2.1–810) | 0.060 (0.0025–0.39) | 0.12 (0.0058, 5.8) | Rothenberg et al., 2016 |
| 6 | Pregnant mothers, Early gestationf | Fecal | Charleston, South Carolina, United States | 28 | 28 (1.1, 1,400) | 0.035 (0.0029, 2.1) | 0.12 (0.00031, 8.9) | Rothenberg et al., 2019 |
| Pregnant mothers, Late gestationf | Fecal | Charleston, South Carolina, United States | 24 | 19 (1.0, 400) | 0.0093 (0.0013, 1.7) | 0.050 (0.0025, 2.0) | ||
| Neonates | Meconium | Charleston, South Carolina, United States | 14–17g | 3.9 (0.64, 11) | 0.0078 (<MDL, 0.078) | 0.34 (0.055, 0.84) |
dw, dry weight; MDL, method detection level; MeHg, methylmercury; THg, total mercury. aTHg and MeHg concentrations were reported in wet weight (Ishihara, 2000; Rand et al., 2016; Caito et al., 2018). Using an average wet/dry ratio for human fecal samples (4.18 unitless) (Rothenberg et al., 2019), the THg and MeHg concentrations were converted from wet weight to dry weight (see Supplementary Table 12 for THg and MeHg concentrations in wet weight). bSamples were collected twice from the participants, in August 1997 and June 1998 (Ishihara, 2000). cSamples were collected twice from eight participants, after trial 1 and after trial 2 (Rand et al., 2016). dMeHg was estimated by subtraction (=total mercury - inorganic mercury). eLate gestation: 36–39 weeks of gestation (Rothenberg et al., 2016). fEarly gestation: 8.3–17 weeks of gestation; late gestation: 27–36 weeks of gestation (Rothenberg et al., 2019). gSample size: THg (n = 14), MeHg (n = 17), and %MeHg (of THg) (n = 14) (Rothenberg et al., 2019).