Mercury and lead are heavy metals heavy metals present in our environment, and whose harmful effects on living beings no longer need to be demonstrated.
In the light of scientific reports, French health authorities have defined a harmful threshold for lead, and for mercury have issued recommendations for preventive purposes for pregnant women.
Below is a summary of the available information:
Heavy metals
Heavy metals are present in our daily environment, in varying levels depending on where we live (town or country) and how we live: in our food, in the air, in dust, in tap water.
Lead (Pb)
Depending on where you live, tap water can contain up to 25 microg/liter of lead, which complies with European regulations until 2013 (after which it will move to an upper limit of 10 microg/liter).
On average, we absorb up to 0.040 mg (40 microg/d) of lead every day through our food (source AFSSA(*) 2006).
Mercury (Hg)
The following is an extract from Afssa – Saisine n° 2002-SA-0014:
“Although mercury (Hg) is present in many foods, it is abundant in fish in its most toxic form: methylmercury (MeHg). As a result, other food sources were considered negligible. Only MeHg presents a danger for pregnant women, not for themselves but for their fetus through in utero exposure, and for young children (up to 2 years of age, during the period of cognitive development) through breastfeeding and a diversified diet.
Considering, however, that for an average weekly consumption of highly contaminated wild fish (percentile 95), contamination essentially contributed by the group of carnivorous, long-lived, fatty pelagic fish such as sea bream, swordfish, marlin, shark and tuna, Hg-T and MeHg intakes are higher than the Provisional Tolerable Weekly Intake (respectively 5 microg/kg bw/w and 3 microg/kg bw/week), and that for an average weekly consumption of highly contaminated wild fish (percentile 95), Hg-T and MeHg intakes are higher than the Provisional Tolerable Weekly Intake (respectively 5 microg/kg bw and 3 microg/kg bw/week).w./wk and 3.3 microg/kg b.w./wk respectively) for the 3-8 age group;
It is considered that, on the basis of available data (toxicological and contamination) and taking into account the dietary habits of the French population, there is no scientific evidence to justify calling into question the fish consumption recommendations of the French National Nutrition and Health Program: at least twice a week, not forgetting oily fish (mackerel, herring, salmon, etc.).
However, given the particular sensitivity of the central nervous system to the toxic action of methylmercury during fetal development, as demonstrated by experimental or accidental data on very high exposures, pregnant or breast-feeding women and young children may be advised to favor a diversified consumption of different fish species, without giving preference, as a precaution, to the consumption of fish likely to present higher levels of methylmercury, such as sea bream, swordfish, marlin, shark and tuna”.
The following is an extract from Saisine n° 2003-SA-0380 linked to Saisine n° 2002-SA-0014
More recently: the agency has reconsidered its recommendations to reduce consumption by pregnant and breastfeeding women and young children:
“for young children, it is recommended that they consume no more than 60 grams of wild predatory fish per week, in addition to their usual consumption of non-predatory fish. This recommendation is in line with the recommendations of the French National Nutrition and Health Program (1).”
(1) Allergies alimentaires : connaissance, clinique et prévention. www. sante.gouv.fr, Theme “Nutrition”.
“for pregnant and breast-feeding women, it is recommended to ensure that they consume no more than 150 grams of wild predatory fish per week, in addition to their usual consumption of non-predatory fish.”
(1) Allergies alimentaires : connaissance, clinique et prévention. www. sante.gouv.fr, Theme “Nutrition”.
This recommendation is limited to pregnant and breastfeeding women, and not to the entire category of women of childbearing age, insofar as, unlike certain contaminants, such as dioxins, which accumulate throughout life, methylmercury is excreted and metabolized (estimated body half-life of 45 days)(2) and its neurotoxic impact would specifically only be exerted during the 2nd and 3rd trimesters of pregnancy.”
See the brochure 2016 ANSES-Recommendations on fish consumption
(*) AFSSA: French Food Safety Agency
USGS study shows 100% of fish from U.S. rivers contaminated with mercury
In a study conducted by the U.S. Geological Survey (USGS), all fish tested in 291 U.S. rivers were found to be contaminated with mercury.
In this study, researchers analyzed sediments from 291 rivers across the USA between 1998 and 2005. The fish sampled were mainly those at the top of the food chain.
The results show that the primary cause of human mercury contamination is due to the consumption of fish and shellfish.