Intra-individual variations of organophosphate pesticide metabolite concentrations in repeatedly collected urine samples from pregnant women in Japan.

BACKGROUND: Low-dose exposure to organophosphate (OP) insecticides during pregnancy may adversely affect neurodevelopment in children. To evaluate the OP exposure levels, single urine sampling is commonly adopted to measure the levels of dialkylphosphates (DAPs), common OP metabolites. However, the inter-day variations of urinary DAP concentrations within subjects are supposed to be large due to the short biological half-lives of the metabolites, and it is thus considered difficult to accurately assess OP exposure during pregnancy with single sampling. This study aimed to assess intra-individual variations of DAP concentrations and the reproducibility of the exposure dose categorization of OPs according to DAP concentration ranges in pregnant women in Japan. METHODS: Urine samples were collected from 62 non-smoking pregnant women (12-22 weeks of gestation) living in Aichi Prefecture, Japan. First morning void (FMV) and spot urine samples taken between lunch and dinner on the same day were collected on five different days during 2 weeks. The concentrations of DAP and creatinine in urine samples were measured using an ultra performance liquid chromatography with tandem mass spectrometry. Creatinine-adjusted and unadjusted concentrations were used for the intraclass correlation coefficient (ICC) calculations and surrogate category analyses. RESULTS: For all DAP metabolites, the creatinine-adjusted single ICCs exceeded 0.4, indicating moderate reliability. Overall, ICCs of spot urine samples taken in the afternoon were better than those taken as FMV. Surrogate category analyses showed that participants were categorized accurately into four exposure dose groups according to the quartile points. CONCLUSION: This study indicated that a single urine sample taken in the afternoon may be useful in assessing OP exposure as long as the exposure is categorized into quartiles when conducting epidemiological studies in early to mid-pregnant women in Japan.

[Folic acid reduces the risk of neural tube defects: awareness and folate intake among pregnant women in 2006].

Folic acid plays an important role in proliferating cells and tissues of the fetus. A randomized control trial demonstrated in 1991 that 4 mg of folic acid supplements successfully prevented 72% of recurrence of neural tube defects (NTDs) in women who had had afflicted pregnancy. In 2000, the Japanese Government recommended women of childbearing age to take 400 microgram of folate supplements per day from 4 weeks prior to and 12 weeks after conception. A questionnaire study was performed in pregnant women by post on their awareness of the role folic acid plays, their life style, and folate intake by dietary consumption. Thirty-five percent of 1,251 pregnant women were aware of the important role of folic acid in the critical stage of fetal development and 31% actually took the supplement. Information on folic acid was obtained through mass media in 47% of the women, through the internet in 17%, through healthcare providers in 13% and so forth. The food record analysis revealed that the dietary intake of folic acid averaged 341 microg/day that was 60 microg less than what was recommended by the Government and that 33 of 86 women took the supplement. Overall, a half of pregnant women are required to take 400 microg folate supplement per day. It is to be stressed that primary prevention of NTDs by periconceptional intake of folic acid is a major public health opportunity and that prevention is more important than cure in the management of NTDs.