Till Christine, Westall Carol A, Koren Gideon, Nulman Irena, Rovet Joanne F
Toronto Rehabilitation Institute, Toronto, Ont., Canada M5G 2A2.
Neurotoxicology. 2005 Aug;26(4):599-613. doi: 10.1016/j.neuro.2005.05.011.
Despite an accumulating body of evidence demonstrating that the visual system is an important target for organic solvent toxicity in adults, little attention has been paid to the visual functioning of children with prenatal exposure to organic solvents. The present study aimed to: (1) determine prospectively whether prenatal solvent exposure increases the risk of visual deficits in infants and (2) assess the relationship between estimates of exposure level and integrity of visual responses. A sample of 21 infants born to women who were occupationally exposed to solvents during pregnancy was compared with 27 non-exposed age-matched control infants. All mothers were recruited from Motherisk, an antenatal counseling service in Toronto, Canada. Contrast sensitivity and grating acuity were assessed using a sweep visual evoked potential (VEP) technique whereas chromatic- and achromatic mechanisms were assessed using a transient VEP technique. Exposure level was estimated from questionnaire data obtained during pregnancy. Testers were masked to exposure status. Results showed a significant reduction in contrast sensitivity in the low and intermediate spatial frequency range in solvent-exposed infants compared to controls (p<0.001). With respect to grating acuity, there was a significant effect of exposure level, with children in the high exposed having reduced grating acuity compared with children in the low exposed group (p<0.025) and controls (p=0.02). Regarding color vision, 26.3% of infants in the exposed group versus 0% of the controls produced abnormal VEP responses to the red-green onset stimulus (p<0.01), but not to either blue-yellow or achromatic stimuli. No differences were found with respect to latency or amplitude of chromatic and achromatic response. These findings suggest that prenatal solvent exposure is associated with selective visual deficits, including reduced contrast sensitivity and abnormal red-green vision. Increasing levels of exposure may lead to further visual deficits affecting grating acuity. These findings support the need for a re-evaluation of current occupational exposure standards for pregnant women.
尽管越来越多的证据表明视觉系统是成人体内有机溶剂毒性的重要靶点，但产前接触有机溶剂的儿童的视觉功能却很少受到关注。本研究旨在：（1）前瞻性地确定产前接触溶剂是否会增加婴儿出现视觉缺陷的风险；（2）评估接触水平估计值与视觉反应完整性之间的关系。将21名母亲在孕期职业性接触溶剂的婴儿与27名年龄匹配的未接触溶剂的对照婴儿进行了比较。所有母亲均从加拿大多伦多的产前咨询服务机构Motherisk招募。使用扫描视觉诱发电位（VEP）技术评估对比敏感度和光栅视力，而使用瞬态VEP技术评估色觉和非色觉机制。根据孕期获得的问卷数据估计接触水平。测试人员对接触状态不知情。结果显示，与对照组相比，接触溶剂的婴儿在低和中等空间频率范围内的对比敏感度显著降低（p<0.001）。关于光栅视力，接触水平有显著影响，高接触组的儿童与低接触组儿童（p<0.025）和对照组（p=0.02）相比，光栅视力降低。关于色觉，接触组26.3%的婴儿对红-绿起始刺激产生异常VEP反应，而对照组为0%（p<0.01），但对蓝-黄或非色觉刺激均无异常反应。在色觉和非色觉反应的潜伏期或波幅方面未发现差异。这些发现表明，产前接触溶剂与选择性视觉缺陷有关，包括对比敏感度降低和红-绿视觉异常。接触水平的增加可能导致影响光栅视力的进一步视觉缺陷。这些发现支持重新评估当前孕妇职业接触标准的必要性。
