A study that checked 21 landfill sites in five countries found there was a 33 per cent increase in birth defects such as spina bifida and holes in the heart when mothers lived within 3km (1.8 miles) of a site.
The researchers from London looked at 1,089 cases of children born with birth defects whose mothers had lived within 7km (4.2 miles) of a landfill site and matched them with 2,366 children without malformations whose mothers lived within a similar zone.
The risks fell the farther women lived from the sites.
"We have found increased risks of many types of congenital anomaly near the landfill sites," said the researchers. "There was a significantly overall increased risk of neural-tube defects, malformations of the cardiac septa (hole-in-the-heart), and malformations of the great arteries and veins in residents near the sites."
But it was not clear whether the increased risk of birth defects was caused by living near toxic waste or by some other factor. They recommended health monitoring for landfill sites and other pollution sources, to include registers of birth defects and assessment of exposure to chemicals.
"Our results show the need for further investigation of the potential environmental and health risks of landfill sites and for a more systematic environmental health surveillance system in Europe." the team added.
Professor Goran Pershagen, from the Institute of Environmental Medicine, Stockholm, stressed that no one knew how much exposure, if any, the women had had to chemicals from the landfill sites. "Overall the evidence is very limited, and the results clearly point to the need for further study." he said.
Friends of the Earth said there were 8,000 landfill sites in the UK of which 2,000 are active. Mike Childs, the senior waste campaigner at FoE said yesterday: "This research is extremely worrying. We havewarned for years that landfill sites are toxic timebombs. There are thousands of landfill sites and no one has a clue what toxic chemicals are dumped in many of them.
"The Government must urgently conduct detailed health studies around rubbish dumps in the UK."