by Andrew Puhanic
Women who are planning to have a baby or who are already pregnant are now being warned to avoid foods containing mercury and are now being encouraged to eat more fish during pregnancy.
It is well-known that certain species of fish (shark, Barramundi and swordfish) contain high levels of mercury. Whereas, other species of fish such as snapper and salmon usually have relatively low levels of mercury. For a comprehensive list of fish to avoid, click here.
A new study published in the Archives of Pediatrics & Adolescent Medicine has concluded that children born from mothers who had been exposed to mercury before and during pregnancy are at risk of developing ADHD-related behaviors in their children.
Published by researchers from the Boston University School of Public Health, data was analysed from more than 780 children between 1993 and 1998 at St Luke’s Hospital, the primary hospital that services the population of greater New Bedford, Massachusetts.
The study was designed in response to the contamination of water in the New Bedford harbor from polychlorinated biphenyls (PCBs) before dumping of polychlorinated biphenyls (PCBs) was banned.
For participants of the study that were found to have up to 1 microgram of mercury per gram of hair, their consumption of fish was associated with a lower risk of ADHD-type behaviours in their children.
Interestingly, for participants of the study who had more that 1 microgram of mercury per gram of hair, it was concluded that there was an increased risk of ADHD-type behaviours in their children.
Mothers that were selected to participate in the study had to meet the following conditions:
Their children must have been born at St Luke’s Hospital, New Bedford. They must have been at least 18 years old. Lived in 1 of the 4 towns adjacent to the contaminated harbor during their pregnancy.
The researchers also found strong protective associations for mothers who consumed fish during pregnancy (of the safe types listed at the beginning of this article). The results are supported by data from a well-characterized birth cohort.
Interestingly, children of mothers who adjusted their total fish consumption (eating varying quantities) did not, in most instances, change associations between mercury levels and ADHD. Also, it was discovered that high mercury levels were found in mothers who were categorized as:
Mothers who were older.
Mother who were married.
Mothers who had a higher household income.
Mother who did not smoke during pregnancy or use illicit drugs the year before birth.
Mothers who consumed more fish during pregnancy, and had children of white race.
In general, the researchers also found no strong correlation to whether males or females were more prone to developing ADHD when exposed to mercury. However, it was noted that associations were stronger in boys.
The findings presented in this study are consistent with the growing literature that proves mothers who are exposed to mercury during pregnancy increase the risk of their unborn child developing ADHD-related behaviours.
The good news is that there is now more evidence to suggest that consumption of fish during pregnancy has a positive impact on fetal brain development.