Occhealth Bulletin
23 July 2009
Parental exposure to pesticides and childhood brain cancer
Category: Reviews
Pesticides are simply agents or substances used to control, repel or kill pests and are extensively used in the agricultural and horticultural industries. The health affects of pesticides on humans depends on their type (chemical or biological in nature) and the length of exposure. The US Environment Protection Agency estimates that there are 10,000-20,000 physician-reported poisonings of agricultural workers annually in the US.
The etiology (study of the causes or origins) of childhood brain cancer is largely unknown and given the incidence of the disease, the second most common cancer in children, is an area of research that is greatly needed. There are different types of brain cancer including astrocytoma and Primitive Neuro Ectodermal Tumors (PNETs). Astrocytomas are cancers that originate in ‘star-shape’ brain cells known as astrocytes; cells which are also found in the spinal column. PNETs develop from cells which are left over from the earliest stages of a baby’s development in the womb and are more common in children than adults (Cancer Research UK). There are a few published studies that have suggested an association between parental exposure to pesticides and the incidence of children with brain cancer. The latest research on the subject was published, last month, by Youn K. Shim and co-workers.
Shim and researchers carried out their study on 526 one-to-one-matched case-control pairs from the four states of Florida, New Jersey, New York (not New York City) and Pennsylvania. The children were all under the age of 10 years between 1993 and 1997 and were residents within one of the four states at the time of their diagnosis. The researchers selected their controls by random digit dialing. A computer-assisted telephone interview system was used to collect information from the biological mothers of the cases and controls. The questionnaire was adapted from one previously used in other childhood cancer studies and was designed to seek information about demographics and exposure (including parents’ ages at child’s birth, maternal education, residential use of pesticides and occupation histories). Job histories of parents were researched covering a two-year period before the child’s birth and information regarding the residential use of pesticides (insecticides, herbicides or fungicides) was also investigated for the same period.
Following analysis of each job for the probability of exposure data, by two independent assessors, the researchers discovered that “a significant risk of astrocytoma was associated with exposures to herbicides from residential use (Odds Ratio=1.9; 95% Confidence Intervals, 1.2-3.0)”. The risk remained elevated when the residential and occupational exposures were combined for both parents. There was little association between the PNETs and pesticides of any class or exposure sources considered. The researchers concluded that these results were consistent with the previous studies suggesting an association between pesticide exposure and risk of childhood astrocytoma but not PNET.
If you would like to know more about pesticides and regulations surrounding their use at work, take a look at the Examinetics, Inc. pathfinder resource on the subject.
Reference:
Shim, YK., Mlynarek, SP. and van Wijngaarden, E. (2009) Parental exposure to pesticides and childhood brain cancer: US Atlantic Coast childhood brain cancer study. Environmental Health Perspectives. 117. pp1002-2117.