Updated on 16/04/2021
Kepone, Chlordecone, Pesticides, Food contaminants, Chemical risks
Long used in the French Caribbean to control the banana weevil, chlordecone can be harmful to human health. ANSES has conducted several studies to assess the chlordecone risk for the French Caribbean population, in particular through the consumption of contaminated food. These have led to toxicity reference values and maximum tolerable contamination limits being defined for foodstuffs. Assessing dietary exposure has also made it possible to formulate food consumption recommendations for local populations.
Chlordecone was used to combat weevils in the banana plantations of Martinique and Guadeloupe from 1972 to 1993. This pesticide is associated with various health problems in humans. It has since been banned, but local populations are still exposed. This is because of its persistence: chlordecone is still present in the soil and can be found in certain plant- and animal-based foodstuffs, as well as in water at certain catchment areas used for drinking water. For many years, the Agency has been involved in assessing the health risks posed by chlordecone for the French Caribbean population. The Agency’s activities in this area are conducted as part of the "Chlordecone" action plans first established in 2008 by the Ministries of Health and the Overseas Territories.
Defining health reference values
ANSES has defined toxicity reference values (TRVs) and estimated the dietary exposure of the French Caribbean population. Its work to estimate dietary exposure drew on the results of surveys and studies of local eating habits and food contamination levels, as well as on all the available scientific data. The Agency has defined a chronic external TRV, which determines the level of exposure by ingestion below which the occurrence of adverse effects in the population is considered negligible. These TRVs are based on toxicological or epidemiological studies. Set previously in 2003 at 0.5 µg of chlordecone per kilo of body weight per day, ANSES now recommends in its 2021 opinion lowering this value to 0.17 µg/kg bw/day. This reduction takes account of new knowledge on the subject, and in particular the latest studies suggesting reprotoxic effects in rodents exposed to moderate doses of chlordecone.
In the same opinion, ANSES developed a chronic internal TRV. This is primarily useful for interpreting biomonitoring campaigns at the population level. It can also be used to assess the risk to the population, based on chlordecone levels observed in blood, unlike the external TRV, which relies on external exposure estimated by combining consumption data and chlordecone concentrations observed in food. The internal TRV was set at 0.4 µg of chlordecone per litre of plasma. This limit value is based on the observation that pregnancy duration decreases with increasing plasma chlordecone concentrations. Reported effects on prostate cancer were also taken into account, but seem to occur at higher levels of exposure.
Why is it not possible to interpret the internal TRV at an individual level?
It would be a mistake to conclude solely from an individual chlordecone blood level result above the internal TRV that a person is ill or at risk of falling ill. There are three main reasons why it is not possible to use the internal TRV for an individual case:
- In public health terms, the primary purpose of biomonitoring is not to evaluate present or future health status, but to guide action in relation to suspected or confirmed exposure. One or more exposure levels are typically set, which will trigger measures to better understand the origin of the result, act on these exposures and verify the effectiveness of the measures through renewed surveillance;
- In biological terms, the result of a biomonitoring measurement may, for the same value, be due to high, one-off exposure that occurred recently and may decrease rapidly, or could equally be due to chronic exposure that would be of far greater concern: it is therefore important that high values lead to additional investigations into the origin of the exposure (confirmation by other measurements, investigation of lifestyle habits, including food consumption, etc.);
- Lastly, in physiological terms, there is great individual variability in the health consequences of an exposure level: with a population considered as a whole, the internal TRV enables the most sensitive individuals to be taken into account.
Recommendations to avoid exposure to chlordecone
In view of the new toxicological benchmarks defined in 2021, a new risk assessment needs to be carried out this year.
Meanwhile, the Kannari study, set up in 2013 by ANSES, Santé Publique France and the regional health observatories with the support of the Martinique and Guadeloupe regional health agencies, identified the supply channels, production areas and populations most at risk of exposure to chlordecone. An analysis of the link between the food procurement method and exposure showed that informal supply channels (home production, gifts, purchases from roadside stalls) resulted in greater exposure than that observed with food obtained from regulated channels (supermarkets and hypermarkets, markets, grocery stores). It appears in particular that the consumption of foodstuffs produced in a contaminated area can lead to the overexposure of populations not following the current consumption recommendations, namely:
- Limit consumption of saltwater fish to four times a week,
- Limit consumption of roots and tubers to twice a week,
- Do not consume freshwater fishery products from areas where fishing is prohibited by prefectoral order.
Following the Kannari study, the Agency recommends extending these recommendations to cover other produce acquired via informal unregulated channels, such as eggs. These recommendations will be reviewed on the basis of the new TRVs.
Lastly, as part of its work on occupational diseases, the Agency is studying the links between exposure to pesticides, including chlordecone, and prostate cancer. During 2021, the results will feed into the negotiations and decisions of the social partners and then of the competent Ministries in the creation of new occupational disease tables.
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