Living in Areas of Heavy Traffic Puts Children at a Higher Risk for Asthma, Autism and Cancer

Getting accustomed to the big city can be difficult for children. In fact, studies confirm that children growing up in certain parts of urban areas may have more difficulty adjusting depending on various life factors. To add to that, a new study links heavy traffic--that often comes with urban areas-- to a child's risk for developing asthma and even autism, in some cases. Worst yet, certain elements from the study may put some children at a higher risk for developing cancer.  

Researchers used the California Department of Transportation's computer model of traffic-related air pollution to estimate pollution exposure in communities across the state. They also used the California Cancer Registry to identify 3,590 children born between 1998 and 2007 who were diagnosed with some type of cancer. Then they compared the two to look for links between traffic and cancer incidence.

They then ranked places in the state according to their degree of pollution resulting from traffic and sorted them into four groups, from the least exposure to the most. They discovered that the more pollution in a place, the higher the incidence of certain kinds of childhood cancers. These included acutelymphoblastic leukemia, a type of blood cancer in which the bone marrow overproduces a type of immature white blood cell called a lymphocyte; tumors in the ovaries, testicles and other reproductive organs; and retinoblastoma, an eye cancer that affects the retina and usually develops in children before they turn 5 years old.

Rest assured, the study notes that these cancers are rare and the risks are relatively small. For example, during the second trimester of pregnancy, moving from one group of pollution exposure to the next-higher group was associated with a 4 percent increased risk of acute lymphoblastic leukemia, a 17 percent increased risk of tumors in the reproductive organs (also known as germ cell tumors) and a 14 percent increased risk of retinoblastoma. (For cases involving both eyes, the risk increased by 19 percent.)

Other signs state that more exposure to traffic may be associated with more cases of non-Hodgkin's lymphoma(another blood cancer) and ependymoma (a cancer of tissues in the brain and spinal cord). However, those may also be linked to chance, according to researchers from the study. 

The study confirms that any increases in risks for cancer were relatively the same during all three trimesters of pregnancy as well as for the first year of the child's life, which means that there is no period, as of yet determined, in early development, when a child is more susceptible to the harmful effects of traffic-related pollution. 

More studies will need to be completed before a direct link can be made, according to researchers. However, they also note to be wary of the risks pollution can cause from heavily populated areas. 

The results were presented Tuesday at the annual meeting of the American Assn. for Cancer Research in Washington.