A friend told me recently: "When we got the diagnosis we felt like they had put a gun to our face." His daughter had been diagnosed with Asperger's Syndrome, a milder form of autism characterized by behavioral problems, including difficulties in social interaction. My friend's reaction to the diagnosis reminded me of similar reactions from other parents whose children have some type of physical or mental disability.

Between 500 and 600 million people worldwide live with a disability. According to World Health Organization statistics, about 10 percent of the children and youth in the world (about 200 million) have a disability. Of these, about 80 percent live in developing countries, although the numbers vary widely across countries. Latin America has about 50 million people with disabilities, of whom 90 percent are unemployed and 82 percent live in poverty.

There are many causes of disabilities in children. They include genetic factors, conditions related to pregnancy or childbirth, conditions affecting newborns as well as other postnatal causes such as injuries, and chronic and infectious diseases. Also among the causes are wars.

The deficiency of certain minerals such as iodine in young children affects their mental development. The same deficiency in mothers during pregnancy can result in varying degrees of intellectual disabilities in the offspring. The good news is that early detection and appropriate primary prevention measures can prevent about 70 percent of cases of childhood disability, according to WHO.

A wide range of toxins, including lead, pesticides and certain types of plastics, in the environment harms the physical and mental development of children. Even some toys contain toxic elements. In a study carried out in six East European and Asian countries, researchers found toxic metals in 29 percent of the toys sampled.

Children are more vulnerable than adults to toxins in the environment, because their higher metabolic rate and not-fully-developed key organs, such as kidneys and liver, cannot flush out the toxins in entirety.

The United States produces about 100,000 synthetic chemicals, with about 1,500 of them entering the market every year. No wonder, almost 17 percent of the children in the US suffer from some form of disability. Developing countries, too, have these problems. And an increasing number of experts are saying the continuous exposure to toxins in the environment is an important cause of disability.

In addition, certain disabilities in children are the result of the mothers' exposure to toxic substances such as alcohol, nicotine and mercury during pregnancy.

Malnutrition is a common cause of disability and a direct result of poverty, which needs to be alleviated. Malnourished children may develop learning disabilities, and could even lose their eyesight or hearing ability. Poverty is both a cause and a consequence of disability, for the costs of caring for disabled children are very high.

Disabilities in children also often affect their educational possibilities. In some developing countries, up to 90 percent of the children with disabilities do not attend school, limiting their chances of a better future.

These factors pose a number of challenges. Disability experts say early intervention can demonstrably improve disabilities in children. Incidentally, many initiatives to address the basic needs of children with disabilities do not require a complicated infrastructure or big expenses and instead can be taken by using community resources and existing infrastructure.

One example of a specific form of local support are programs designed and implemented by local communities, a concept developed by WHO in the late 1970s and early 1980s. The plan stresses the rehabilitation, equalization of opportunities and poverty reduction for all children and adults, which would benefit all community members and teach social and community leaders to work together.

Thankfully, the de-institutionalization of children with disabilities has become the norm. But for it to be truly effective, it must be accompanied by the development of suitable community structures for the care and education of children with disabilities.

Educational institutions should include children with disabilities in regular education programs and must stop segregating them from other children. Inclusive education means responding to the needs of children with physical and mental disabilities by keeping them in mainstream educational settings.

Colombia's "New Schools" and Brazils' Child Friendly Schools are examples of inclusive educational approaches. Costa Rica has established a National Resource Center for Inclusive Education that supports schools with an inclusive approach toward children with disabilities and at the same time helps improve the quality of education for all students. Needless to say, government support is crucial for such programs to be successful.

It is extremely important to improve the situation for not only disabled children, but also their families, because siblings could resent the extra attention given to children with disabilities and poor parents could be overwhelmed by the enormous financial, physical and emotional demands of taking care of them.

These considerations underscore the need for a holistic approach to children with disabilities, which include developing national policies that promote opportunities for disabled children, and properly allocating resources to meet their needs. Also, it is important that people remove the social stigma associated with children with disabilities.

Children with disabilities and their families, if possible, must be invited to participate in the planning of programs and projects that concern them. And employment agencies should work with skill-training and employment agencies to offer children with disabilities jobs that take into account the abilities they possess.

Addressing the needs of children with disabilities is not only a duty that we as a society must fulfill. It is also an expression of the compassion and intelligence with which we can build a better society.

The author is an international public health consultant.