PARIS (Reuters) – An investigation into why a dozen or so babies born without hands or arms in a handful of rural areas of France since 2000 has so far been unable to determine causes, an interim report published by the Health Ministry showed on Friday.

The babies with limb defects were born in the rural Ain region of eastern France, near the Swiss border, as well in the regions of Morbihan and Loire-Atlantique in western France.

Media reports of the births have raised alarm among the French public that they might be caused by some kind of toxin in food, water or air, or that pesticides might be responsible.

But the long-awaited interim report by Sante Publique France, an agency of the Health Ministry, offered no relief to families looking for answers.

The expert panel concluded that there was no evidence of a “cluster” of cases in the Ain region, where it said there were six cases. It said there was a cluster in Morbihan, which it said involved three babies.

Additional investigations are to be carried out in nearby Loire-Atlantique. It gave no figures for that area, but media reported several cases there.

In the 265-page document, experts said it was impossible to draw definitive conclusions and that possible environmental factors would be assessed at a later stage.

“Scientific studies screening, questionnaires and local environment testing have been conducted by Sante Publique France which has not identified an obvious cause,” the report read.

A second report is expected by the end of the year.

Epidemiologist Emmanuelle Amar, who first revealed the birth defects in Ain, told Reuters last year the only thing mothers of the affected babies had in common was that they lived in cereal-growing areas amid fields of corn and sunflower.

“We do not have answers to our questions,” Samuel Bernard, father of a daughter born in 2013 with a missing left arm in Morbihan told France Info radio, adding he and other families were asking for an independent investigation to take place.

Hospital registries show limb defects occur in 1.7 of every 10,000 births, or about 150 cases per year in France. Birth defects can have multiple causes, including chromosome disorders, drug use or exposure to toxic substances.

But authorities only have six registries covering around 20% of France’s population to produce the figures, making a nationwide investigation difficult.

In the late 1950s and early 1960s, about 10,000 babies worldwide were born with malformed or missing limbs after their mothers received the drug thalidomide to treat morning sickness.

(Reporting by Matthias Blamont; Editing by Edmund Blair)