Air pollution and birth defects

Dr. Robert Scherpbier, UNICEF's Chief of Health and Nutrition in China, recently sat down for an interview with VOA on the effects of air pollution on children. Many parents are naturally concerned. We think you will find the discussion fascinating.

Frances Alonzo (VOA): My program is on empowering women.  In this case, to empower mothers to protect their children from the harmful effects of pollutants in the regions where they live.  My questions are as follows:

VOA: Please introduce yourself.

My name is Robert Scherpbier. I am the Chief of Health and Nutrition in UNICEF China. We work in the most disadvantaged communities in China, in particular in the seven western provinces Gansu, Guizhou, Qinghai, Sichuan, Tibet, Yunnan, and Xinjiang.

VOA: Is there a link between pollution and birth defects in China?

To answer that question I'd like to talk about pollution first and then about birth defects.

Air pollution causes 3.3 million deaths globally, of which 1.3 million due to outdoor air pollution and 2 million due to indoor air pollution.

Both forms occur in China, and indoor air pollution is likely to be more important as a risk factor for disease than outdoor air pollution.

Indoor air pollutionis an established risk factor for pneumonia, chronic obstructive pulmonary disease (COPD)and lung cancer. It is likely that indoor air pollution is linked to low birth weight, tuberculosis, cataract, asthma and other cancers.

Globally almost half of the indoor pollution related deaths are due to pneumonia in children under 5 years of age. In homes where biomass fuels and coal are used for cooking and heating, PM levels may be 10–50 times higher than the guideline values. 

Outdoor air pollutionremains a serious problem in cities throughout the world, particularly in the megacities of developing countries and it is estimated that a quarter of the world population is exposed to unhealthy concentrations of air pollutants. Children are particularly at risk due to the immaturity of their respiratory organ systems.

We do not have reliable information on incidence of birth defects that allow comparisons between countries on even within countries. Birth defects can present themselves in many ways. The quality of diagnostic procedures affects the detection of the various birth defects, and the reported incidence.

However we do have reliable information on the importance of children dying from birth defects, relative to other causes of death.

According to estimates by the Chinese Ministry of Health, around 9% of all under-five deaths are due to birth defects (or congenital anomalies). Roughly 28,000 newborns die as a result of a birth defect every year.

There is no single cause for birth defects. The causes of birth defects are many, including:

• Inadequate nutrition, such as lack of folic acid and maternal obesity,
• Infectious diseases such as syphilis and rubella,
• Environmental factors,
• Genetic factors

Since of these many factors are at play simultaneously, it is often difficult to attribute birth defects to a single cause.

More is known on how to prevent nutritional and infectious causes than on how to address the more complex environmental and genetic factors.

By reducing air pollution levels, we can help countries, including China, to reduce the global burden of disease from respiratory infections, COPD, and lung cancer.

VOA: What are the most common birth defects seen in Chinese infants and are those defects definitively linked to pollution?

According to Ministry of Health reports, congenital heart defects and neural tube defects are most commonly observed.

Congenital heart defects are associated to congenital syphilis and rubella. Both are preventable diseases. Syphilis testing at ANC and rubella vaccination are standard policy.

Neural tube defects are associated with folic acid deficiencies and maternal obesity. The former is a problem everywhere. The latter increasingly in the richer urban areas.

VOA: What pollutants are the culprits?

There is no evidence birth defects are linked to air pollution. Air pollution is an important risk factor for pneumonia, a much larger cause of under-five death than birth defects. It is probable that air pollution is linked to low birth weight, which also is much more important as a mortality cause than birth defects.

VOA: What can expectant mothers do to prevent these birth defects from happening? 

Birth defects have many different causes. The causes most amenable to interventions are those due to infection and nutrition. Before pregnancy women should ensure they are vaccinated against rubella (and hepatitis B, that they are not obese and take folic acid supplements. Pregnant women should attend ANC clinics to be tested for syphilis (and hepatitis B), and treated if positive.

VOA: Is there a nutritional link to birth defects?

Obese women and women with folic acid deficiency are at higher risk of delivering a child with a birth defect.

VOA: In various news reports, the Chinese public is seen wearing face masks, do the masks help?

There is no evidence that face masks help.

VOA: What regions of the country have the highest incidents of birth defects linked to pollution?

We do not have reliable information on incidence of birth defects that allow comparisons between countries on even within countries. Birth defects can present themselves in many ways. The quality of diagnostic procedures affects the detection of the various birth defects, and the reported incidence.

However we do have reliable information on the importance of children dying from birth defects, relative to other causes of death.

Provincial data on mortality due to birth defects will be released as collaboration between UNICEF and MoH.

VOA: How can women help themselves and their unborn children in preventing birth defects?

Reduce infectious diseases, improve nutrition, genetic testing for families with birth defects

VOA: And more importantly, are these the questions mothers should be asking or is the international community missing the point as far as pollution and its effects on the health of its children?

The Chinese public and media place too much attention on birth defects. Contrary to popular opinion, the proportion of children dying from birth defects in China is low compared to other countries with similar under five mortality rates.

In 17 countries with similar child death rates as in China (i.e. with child mortality between 20 and 25/1000 live births), the proportion of newborn deaths due to birth defects, ranges from 8% to 28%. In fact, the lowest figure is from China.

Other very common causes of under-five mortality, such as birth asphyxia, low birth weight and pneumonia deserve higher policy attention.