Such procedures "mix human and animal biological elements to such an extent that it questions the very concept of being entirely human," the report said. This raises "grave and complex ethical difficulties."

Some ethicists worry that the experiments might force society to make confounding decisions on whether, say, a human-chimp mix would have human rights. Other concerns are that such a creature could suffer from being outcast as a "monster," from having a chimp as its biological father or mother, or from unusual health problems.

Some inter-species mixtures are powerful research tools, the report said.

This "became clear about a decade ago in a series of dramatic experiments in which small sections of brains from developing quails were taken and transplanted into the developing brains of chickens. The resulting chickens exhibited vocal trills and head bobs unique to quails, proving that the transplanted parts of the brain contained the neural circuitry for quail calls. It also offered astonishing proof that complex behaviours could be transferred across species."

Later research has spawned human-animal creations, the report said. These usually die at the embryonic stage, but often survive if the mixtures involve only a few cells or genes transferred from one species to another.

The council cited the following examples:

* In 2003, scientists at Cambridge University, U.K. conducted experiments involving fusing the nucleus of a human cell into frog eggs. The stated aim was to produce rejuvenated "master cells" that could be grown into replacement tissues for treating disease. It was not clear whether fertilization took place, but "some kind of development was initiated," the report said.

* In 2005, U.K. scientists transplanted a human chromosome into mouse embryos. The newly born mice carried copies of the chromosome and were able to pass it on to their own young.

* The company Advanced Cell Technologies was reported, in 1999, to have created the first human embryo clone by inserting a human cell nucleus into a cow's egg stripped of chromosomes. The result was an embryo that developed and divided for 12 days before being destroyed.

* Panayiotis Zavos, the operator of a U.S. fertility laboratory, reported in 2003 that he had created around 200 cow-human hybrid embryos that lived for about two weeks and grew to several hundred cells in size, beyond the stage at which cells showed the first signs of developing into tissues and organs.

* In 2003, Hui Zhen Sheng of Shanghai Second Medical University, China, announced that rabbit-human embryos had been created by fusing human cells with rabbit eggs stripped of their chromosomes. The embryos developed to the approximately 100-cell stage that forms after about four days of development.

The council made 16 recommendations, including that it should be illegal to mix animal and human sperm and eggs, or to create an embryo containing cells consisting of both human and animal chromosomes.

"The fertilisation of animal eggs with human sperm should not continue to be legal in the U.K. for research purposes," said Calum MacKellar, the council's director of research.

"Most people are not aware that these kinds of experiments have been taking place in the U.K. and find it deeply offensive. Parliament should follow France and Germany and prohibit the creation of animal-human hybrid embryos."

In a report published in 2004, the President's Council on Bioethics in the United States also advocated prohibiting the creation of animal-human embryos by uniting human and animal eggs and sperm. A draft law introduced in U.S. Congress by Senator Samuel Brownback (R-Kan.) would outlaw the creation of human-animal mixtures.

A 2005 report from the U.K. House of Commons Science and Technology Committee takes a more liberal stance, saying such embryos could be legal for research purposes if they are destroyed within 14 days.

"While there is revulsion in some quarters that such creations appear to blur the distinction between animals and humans, it could be argued that they are less human than, and therefore pose fewer ethical problems for research than fully human embryos," the committee wrote.

"The human brain is a precious and vulnerable organ," said study author Dr. Philippe Grandjean, an adjunct professor at Harvard School of Public Health in Boston. "And because optimal brain function depends on the integrity of the organ, even limited damage may have serious consequences."

Researchers fear a 'silent pandemic' of brain development disorders has been triggered in babies exposed to toxic chemicals while still in the womb.

Some experts suggest that what they don't know about the chemicals may be even scarier than what they know.

They want new chemical limits set which reflect a higher level of suspicion about their potential for harming unborn babies.

But Warren Foster, director of the Centre of Reproductive Care at Ontario's McMaster University, said there is no data to support the idea that chemical exposure is harming children or that diseases such as autism are caused by such pollution.

"The kids actually have to be exposed," Foster said from Hamilton. "Simply because things are in the environment does not necessarily mean that children are exposed or are exposed to the concentrations necessary to create the neurotoxicity."

Their submission to an ethical inquiry into increased survival rates reads: "A very disabled child can mean a disabled family. If life-shortening and deliberate interventions to kill infants were available, they might have an impact on obstetric decision-making, even preventing some late abortions, as some parents would be more confident about continuing a pregnancy and taking a risk on outcome."

Geneticists and medical ethicists are supporting the proposal - as are some mothers of severely disabled children - but a prominent children's doctor described it as "social engineering".

The college's submission continues: "We would like the working party to think more radically about non-resuscitation, withdrawal of treatment decisions and active euthanasia as they are ways of widening the management options available to the sickest of newborns."

Although the college says it is not formally calling for active euthanasia to be introduced, it wants the mercy killing of newborn babies to be debated by society.

John Wyatt, consultant neonatologist at University College London, said: "Intentional killing is not part of medical care. The majority of doctors and health care professionals believe that once you introduce the possibility of intentional killing into medical practice you change the fundamental nature of medicine."

"This is actually logical since acute otitis media is virtually always connected to viral respiratory infection," said Dr. Aino Ruohola of Finland's Turku University Hospital, lead author of the study.

She says her team's findings have implications for treatment.

Antibiotics are effective against the bacteria that cause ear infections but have no effect on the viruses. That means standard treatment for ear infections - antibiotics - is at best partially effective in most cases.

"Based on this and previous research, it is possible that viruses cause a considerable proportion of clinical treatment failures. Thus, in these cases a new antibiotic is not necessarily the best choice although bacteria resistant to common antibiotics are wide-spread," Ruohola said in a news release.

According to the study, published in the Dec. 15 edition of Clinical Infectious Diseases, the good news is that many children recover on their own without antibiotic treatment.