Valeurs d'imprégnation critiques aux PCB dans le sang

Critical blood concentration levels for PCBs
National study coordinated by the Agency and InVS on PCB concentration levels in people who regularly consume freshwater fish

Why study PCB levels in the body?

In humans, exposure to PCBs mainly occurs through food consumption, and Agency's 2007 assessment of food-related exposure to PCBs in the French population showed that in the most highly exposed populations, mainly children and adults who consume large amounts of fish, the Tolerable daily intake (TDI) was exceeded.
The level of toxicity of PCBs is not directly related to the quantity consumed at a given point (periodical exposure to PCBs through eating a single highly contaminated food has little impact on health), but is essentially dependent on the amount accumulated in the blood and fatty tissues over time (the concentration level in the body). PCBs can accumulate in the body's fatty tissues and can then be found in high levels in mother's milk and blood-lipid fractions.

What impact can chronic exposure to PCBs have on health?

The impact of PCBs on human health has been examined in various epidemiological studies conducted in the United States, Canada and in Europe.
In 2007, the Institut National de Santé Publique du Québec (INSPQ) provided a critical overview of all the studies published since 1997 in order to analyse the causal relationship between exposure to PCBs and health problems in exposed individuals.
In Europe, the impact on health of chronic exposure to low doses of PCBs has been demonstrated through analysis of the results of the PCBRISK epidemiological study. This study, conducted in a historically polluted region of eastern Slovakia, is the most exhaustive European epidemiological study to date in terms of range of exposure and PCB concentration levels.
To date, the effects on health most commonly found to be linked to human exposure to PCBs are the following:
- impaired mental and motor development and disturbances in immune mechanisms in children exposed in utero or during the perinatal period through breastfeeding and up to age three,
- endocrine system impairments (especially the thyroid) in the rest of the population.

Other effects have sometimes been reported, but no link of cause and effect with chronic exposure to PCBs has been clearly established; this is the case with fertility problems in men, certain metabolic disturbances (glucose metabolism in particular) and adult neurological disorders.

What does “critical concentration level” mean?

Critical concentration levels are the body burden levels of PCBs below which the probability of suffering from health problems is considered to be insignificant.
They serve as a reference:
- to understand the concentration levels observed in various populations,
- to guide public policy in order to protect the general public and more specifically the populations at risk (women of childbearing age, breastfeeding women, children under age three and people who regularly consume highly contaminated foods, for instance due to a local source).

To date, the critical concentration levels reported in the international literature for women of childbearing age or who breastfeed and for children under age three vary between 700 and 1000 ng of total PCB per gram of maternal plasma lipids. These levels have been established based on effects observed in children exposed during the perinatal period.

What is the Agency position?

In the current state of knowledge, the Agency considers that the effects of PCBs on the mental and motor development of children exposed in utero are the best-documented critical effects for establishing the critical concentration level in humans, and therefore recommends setting the critical concentration threshold for pregnant women, women of childbearing age, breastfeeding women and children under age three at 700 ng of total PCB per gram of plasma lipids.
Due to the persistent nature of PCBs in the body and the associated gradual rise in concentration levels with age, the Agency recommends that this threshold level also apply to young girls and teenage girls.

In boys over age three, adult men and women beyond childbearing age, the Agency considers that the available data are fragmentary, in some cases even contradictory and difficult to interpret on a clinical level.
the Agency nonetheless recommends setting the critical concentration level for the rest of the population at 1800 ng of total PCB per gram of plasma lipids.

April 2010