Emmanuel Macron started a four-day visit to the French West Indies on Thursday, flying in to Martinique directly from New York, where he addressed the UN General Assembly on Tuesday.
The French West Indies consists of four territorries in the Antillean archipelago Guadeloupe, Saint Barthelemy, Saint Martin and Martinique.
These were former French colonies that are now French overseas territories.
High toxicity, 90% of population concerned
Emmanuel Macron's visit to Martinique stems from a decades-old controversy concerning a toxic pesticide called Chloredecone, proven to be carcinogenic.
Chloredecone was banned in the US in 1977
However, despite the ban, the pesticide continued to be used by banana farmers in the French West Indies till 1993.
The island of Guadeloupe has recently been infested with the Sargassum toxic algae, which, when dry, produce hydrogen sulphate and ammonia.
An official complaint was launched Thursday in Paris against the government's negligence to deal with the toxic algae.
Rising cases of prostate cancer
The effects of Chlordecone are said to last up to 600 years. The chemical has been detected in French West Indies soil, in certain vegetal matter and some water samples.
French health services say more than 90 per cent of the population is exposed to Chlordecone.
The chemical is suspected to be the reason for many cases of prostate cancer in the French West Indies.
Prostate cancer in the region is estimated to be twice as much as in mainland France.
Cyclone Kirk on the horizon
Coincidentally, the last time Macron visited the region in 2017, if was after Hurricane Irma caused considerable damage to these islands.
Macron's present visit comes a year later, when another cyclone is about to hit - Cyclone Kirk.
Both Martinique and Guadeloupe were placed on orange cyclonic alert Thursday.
Schools shut and public meetings were prohibited.
Macron cancelled a visit to the city centre of Fort de France, Martinique's capital.