A new report by the World Health Organization says environmental hazards are responsible for the deaths of several million children every year. The report, issued Friday by WHO, is the first-ever study to highlight children's susceptibility to harmful chemical exposures at different periods of their growth. Lisa Schlein reports from WHO headquarters in Geneva.

The World Health Organization says, when it comes to the dangers posed by enviromental hazards, children are far more vulnerable than adults.

The WHO report, compiled by a group of scientific experts from 18 countries, says four million children under age five die each year because of polluted air and water and exposure to various kinds of chemicals.

An environmental medical expert for WHO, Jenny Pronczuk, says children become susceptible to environmental hazards from conception. "For example, if you look at lead exposure. The effect of lead is going to be different if the child was exposed in utero because the mother has lead. Lead goes to the bones and the lead of the mother goes into the bones of the child that is generating the bones. So, lead exposure in utero is going to have a completely different effect than lead exposure when the child is 12 or 15 years old or 18 years old," she said.

WHO says environmental hazards can cause miscarriage, still birth, low birth weight and birth defects. There is emerging evidence, according to the report, that exposure to environmental chemicals during childhood can increase the risk of certain diseases in adults, such as cancer and heart disease.

Because of the susceptible and vulnerable nature of the fetus, Dr. Pronczuk says it is important that prospective fathers, as well as mothers, try to protect themselves from environmental risks. "In the past, we used to say ... it is the woman ... who carries the baby and she may transfer pollutants to the embryo or the fetus. But now we know that the father can also transfer some of the effects of his exposure to a pollutant," she said. "So, maybe one of the key messages is ? a working father and mother should be advised about whether they are using chemicals, are they applying pesticides? Are they working in an industry where they are using solvents?"

The World Health Organization says Africa is the region with the most environmentally related diseases, followed by parts of Southeast Asia.