Assessing the risks of chlordecone exposure in the French Caribbean

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 is the level of exposure by ingestion below which the occurrence of adverse effects in the population is considered negligible. This level of exposure is estimated by combining consumption data with the observed concentrations of chlordecone in food. The TRV is based on toxicological and 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, and in particular the latest studies suggesting reprotoxic effects in rodents exposed to moderate doses of chlordecone. ANSES will use this new TRV to update the food risk assessment, revise the interpretation of dietary exposure and review its recommendations.

In the same 2021 opinion, ANSES also developed a chronic internal TRV. Based on the level of chlordecone measured in blood, this value is useful for interpreting biomonitoring campaigns at the population level. It also represents a target to be achieved: to have as many individuals as possible below this value. 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. On the basis of this chronic internal TRV, ANSES will quantify and specify the characteristics of the profiles of French Caribbean inhabitants for whom a proven health risk cannot be ruled out, in light of current scientific knowledge.

It should be noted that while the chronic internal TRV can be used to identify typical profiles of people at risk, it cannot identify individuals at risk. It is in no way an indicator of a person's health status and cannot therefore be used to interpret a measurement of chlordecone levels in blood or guide an individual's medical follow-up. Indeed, for a given person, the result of a single chlordecone blood level measurement provides no information on the source or duration of exposure. Furthermore, the same level may have different health consequences, due to large variations in metabolism, sensitivity and exposure circumstances. For a population considered as a whole, the chronic internal TRV enables this variability to be taken into account by including the most sensitive individuals.

Recommendations to avoid exposure to chlordecone

In view of the latest knowledge available on the risks associated with exposure to chlordecone, the ChlorExpo study on dietary exposure of the French Caribbean population to chlordecone was launched by ANSES in early 2021. It aims to take into account this population's food procurement, preparation and cooking practices. New practical recommendations for limiting exposure, based in particular on food preparation and cooking methods, may therefore be issued. The results of the study are expected in 2024.

Until these results become available, the Kannari study (PDF), 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 has studied the links between exposure to pesticides, including chlordecone, and prostate cancer. The scientific evidence developed during its expert appraisal 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.