In utero Pesticide Exposure and Pediatric Leukemia
Pesticide exposure is a global health concern, as their toxic effects are well known. A Brazilian study published in 2013 highlights a connection between exposure to pesticides in the months directly before and after childbirth and childhood leukemia development.
The study, “In Utero Pesticide Exposure and Leukemia in Brazilian Children < 2 Years of Age (Ferreira),” notes that certain chemicals contact may increase the risk of acute leukemia in children younger than 2.
Ferreira examined the link between pesticides and pediatric leukemia by interviewing mothers across Brazil for eight years. The scientists, working with the Brazilian Collaborative Study Group of Infant Acute Leukemia, interviewed the mothers of 252 children with leukemia. They also interviewed the mothers of 423 children with nonmalignant diseases as a control group.
Previous studies linked pesticide use and cancer development, including childhood leukemia.
“Pesticide exposure during childhood may occur in many ways, either through contamination of their parents’ work clothes or through household residues in water, air, soil and food,” Ferreira states. “However, the short latency period for leukemias diagnosed during the first year of life suggests that intrauterine exposures may play a paramount role in this process.”
Leukemia is a group of cancers beginning in the bone marrow causing abnormal white blood cell counts. Leukemia is traditionally broken down into four main types: acute lymphoblastic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, and chronic myeloid leukemia.
Ferreira focuses on acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). ALL occurs when the bone marrow makes too many immature lymphocytes, a white blood cell type. ALL is the most common childhood cancer, affecting myeloid white blood cells.
The researchers collected data from the mothers from 1999 to 2007. Scientists asked the mothers about their pesticide use while pregnant. They then sorted those exposure by toxological characteristics.
“Exposure was evaluated based on the mother’s report of any contact with pesticides during the three months before pregnancy, throughout each pregnancy trimester, or during the three months after birth. Scientists asked the mothers what types of pesticides they were exposed to, including whether or not they were household or agricultural pesticides.”
“Few studies of pesticides and leukemia in very young children have been published,” Ferreira says. “Additionally, most studies of association between childhood leukemias and pesticides have focused on parents’ occupational exposures.”
The scientists found pesticide use at any time during the pregnancy reported by 60.7% of AML case mothers, 36.4% of ALL case mothers, and 21.3% of the control mothers for children aged 0 – 12 months when diagnosed. Scientists found 48.4%, 47.6% and 31.4% of AML, ALL and control mothers of children diagnosed between 12 and 23 months of age reported pesticide exposure during pregnancy.
This data shows a strong association between both ALL and AML diagnoses and periconceptual exposure among children diagnosed before 11 months of age. AML diagnosis likelihood increased with exposure during all time periods among the same group, particularly for third trimester exposures and in the three months after birth.
“Our findings suggest that children whose mothers were exposed to pesticides 3 months before conception were at least twice as likely to be diagnosed with ALL in the first year of life compared with children whose mothers did not report such exposure,” Ferreira states.
The study went into detail examining seven particular pesticides: Prallethrin, Permethrin, Imiprothrin, Esbiothrin, Tetramethrin, d-Phenothrin, and d-Allethrin. Prallethrin and d-Phenothrin in particular were shown to have strong connections to both AML and ALL diagnoses in the first 11 months after birth. Both Prallethrin and d-Phenothrin belong to the pyrethroid class of insecticides.
The U.S. Environmental Protection Agency cancelled permission to use phenothrin in several flea and tick products in 2005, at the request of manufacturer Hartz Mountain Industries. The products were linked to a range of adverse reactions in cats and kittens, including hair loss, salivation, tremors and death. While the sale and distribution of Hartz’s phenothrin-containing flea and tick products was terminated in 2006, the chemical remains available in flea and tick products for dogs.
Phenothrin is often used in wasp and hornet sprays, home foggers, moth proofing sprays, roach sprays and multi-purpose insect sprays. Brands known to use phenothrin include Anvil, Bengal, Blackjack, Enforcer, Evercide, Real-kill, Sergeant’s and Sure-Hit.
d-Phenothrin is a pyrethroid insecticide, a man-made version of the natural pyrethrin repellant found in chrysanthemum flowers. Phenothrin is used in various household sprays for killing adult fleas and ticks. It is also used as lice treatment.
Prallethrin is a pyrethroid insecticide currently used in the United States. It is the main ingredient in the consumer insecticide Hot Shot Ant & Roach plus Germ Killer. It is also used in various Bengal-brand sprays and foggers as well as a number of chemicals used by exterminators. Other products using Prallethrin include Spectracide Wasp and Hornet Killer, Raid Wasp and Hornet, and Raid Flying Insect.
Prallethrin has historically been used for domestic and public health pest control, as well as in greenhouse plant pest control.
The primary manufacturer of Prallethrin is Sumitomo Chemical Company, Ltd., based in Ehime, Japan.
If you believe your child’s recent leukemia diagnosis might be related to exposure to d-phenothrin, prallethrin or another pesticide, please contact the trial attorneys of Allen Stewart, P.C. The firm has decades of combined experience in helping those who have developed cancer due to toxic exposure.