Fungi toxins in corn cause birth defects

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Agri. & Environ.

Fungi toxins in corn cause birth defects

By fc

Feb 9, 2006, 00:49

New data suggests contaminated corn may be the cause of the outbreak of

neural tube defects in the Rio Grande Valley during the early 1990's.

Eating tortillas tainted with fumonisin during the first trimester of

pregnancy may lead to neural tube defects (NTD), suggests a study published

Sept.

29 in the on-line magazine Environmental Health Perspectives.

Neural tube defects are embryonic defects of the brain and spinal cord

resulting from failure of the neural tube to close. Spina bifida and

anencephaly

(failure of anterior tube closure) is the most common, according to the study.

The researchers of the study intended to investigate whether consumption of

tortillas contaminated with fumonisin caused the outbreak of neural tube

defects during 1990-1991 in Cameron County, Texas. In Texas, there were 40

clusters of neural tube defects during the period of outbreak.

The human outbreak of neural tube defects occurred during the same crop year

as epizootics, attributed to exposure to fumonisin, a mycotoxin produced by

the molds Fusarium verticillioides that often contaminates corn, according to

the article. The coincidence prompted researchers to suspect the outbreak of

neural tube defects may be also associated with fumonisins-tainted corn.

In the population-based case control study, researchers estimated the

exposure to fumonisins during the first trimester from a postpartum

sphinganine:shingosine ratio (sa:so ratio), a marker for fumonisin exposure

measured in

maternal serum, and corn tortilla intake based on the maternal recall.

The study recruited 225 Mexican-American women with NTD-affected pregnancies

and 378 Mexican-American women with healthy births. Among them, 184

NTD-affected women and 225 control women participated in an interview. Among the

interviewed, 163 case women and 189 control women provided blood samples for the

sa:so ratio test.

The study found that after considering cofounders including body mass index

(BMI), serum B12, and date of conception, those who consumed 301 to 400

tortillas during the first trimester were more than twice likely to have

NTD-affected pregnancies compared to those who consumed 100 or less.

Consumption of 401-800 tortillas during the first trimester was associated

with a slightly decreased risk of NTD. Consumption of more than 800 tortillas

was not associated with any increased or decreased risk.

Based on the postpartum sa:so ratio, increased exposure to fumonisins was

associated with an increased risk of NTD, except for those who experienced the

highest exposure (sa:so>0.35). Highest exposure was associated with a

decreased risk of NTD.

The reduced risk of fumonisin on the group with the highest exposure can be

explained by the assumption that stillbirths or fetal death can be caused by

the highest exposure at certain thresholds.

The results of the study suggest the risk of neural tube defects increases

as exposure to fumonisins increases to a threshold, at which fetal death can

be caused.

The study was conducted by Stacey A. Missmer and colleagues at Harvard

School of Public Health, Boston, MA, Brigham and Women's Hospital and Harvard

Medical School, Boston, MA, Texas Department of State Health Services, Austin,

TX, and Boston University School of Public Health, Boston, MA, and the Medical

Institute, Austin, TX.