Table 3.
Proportion of children with diagnosed autism or extreme levels of autistic traits by proxies for increased mercury exposure
| Proxy for mercury exposure | Diagnosed autism, % (n) | Autistic traits, % (n) | |||
|---|---|---|---|---|---|
| Poor social cognition | Poor sociability | Poor coherence | Repetitive behavior | ||
| White fish frequencya | |||||
| Not at all | 1.21 (27) | 16.1 (204) | 11.6 (191) | 12.1 (147) | 6.5 (90) |
| Once in 2 weeks | 1.33 (65) | 12.5 (386) | 10.4 (397) | 9.4 (277) | 6.0 (199) |
| > once a week | 1.37 (69) | 11.9 (397) | 12.3 (494) | 9.7 (314) | 5.6 (197) |
| P (2df) | 0.640 | < 0.001 | 0.029 | 0.026 | 0.481 |
| Oily fish frequencya | |||||
| Not at all | 1.23 (63) | 13.8 (407) | 12.6 (480) | 10.9 (308) | 6.0 (195) |
| Once in 2 weeks | 1.49 (60) | 13.2 (354) | 10.3 (334) | 10.0 (256) | 5.8 (165) |
| > once a week | 1.27 (38) | 11.1 (226) | 11.0 (268) | 8.7 (174) | 5.9 (126) |
| P (2df) | 0.672 | 0.017 | 0.010 | 0.044 | 0.971 |
| Shellfish frequencya | |||||
| Not at all | 1.35 (132) | 13.0 (801) | 11.0 (834) | 10.2 (598) | 5.8 (384) |
| Any | 1.23 (29) | 12.1 (186) | 13.1 (248) | 9.4 (140) | 6.3 (102) |
| P (2df) | 0.527 | 0.352 | 0.008 | 0.414 | 0.438 |
| Had amalgam fillings inserted in pregnancy | |||||
| Yes | 1.09 (12) | 12.8 (222) | 10.0 (213) | 10.0 (169) | 6.7 (127) |
| No | 1.52 (67) | 12.8 (700) | 11.7 (786) | 9.9 (516) | 5.7 (332) |
| P (1df) | 0.283 | 0.995 | 0.029 | 0.920 | 0.092 |
| Had amalgam fillings removed in pregnancy | |||||
| Yes | 1.03 (15) | 13.8 (155) | 9.1 (126) | 10.6 (118) | 6.0 (73) |
| No | 1.58 (126) | 12.6 (767) | 11.7 (873) | 9.8 (567) | 5.9 (386) |
| P (1df) | 0.110 | 0.284 | 0.006 | 0.405 | 0.865 |
| Number of amalgams in mouth in pregnancy | |||||
| 0 | 1.62 (11) | 13.5 (60) | 12.4 (77) | 11.4 (47) | 6.7 (34) |
| 1–3 | 1.29 (25) | 13.5 (188) | 14.0 (250) | 8.6 (112) | 6.8 (101) |
| 4+ | 1.57 (96) | 12.6 (612) | 10.4 (600) | 9.9 (463) | 5.9 (305) |
| P (2df) | 0.677 | 0.653 | < 0.001 | 0.196 | 0.355 |
All associations with P < 0.10 are italicized
df degrees of freedom
aAmount consumed by mother as reported at 32 weeks gestation