根據過去的研究指出，兒童發展遲緩的盛行率約為10%，從台灣發展遲緩兒童通報資料發現近幾年發展遲緩兒童人數有增加的趨勢。從過去的研究中可以得知兒童的認知行為與智力和重金屬如：汞、鉛、鎘等的暴露有關；但是在認知行為以及智力上反映出的結果只是發展的表徵之一，目前仍缺乏重金屬濃度與兒童發展的直接相關證據。
本研究以橫斷的研究設計（cross-sectional study design），以民國90年10月至97年9月出生戶籍登記為南投縣某鄉0至6歲兒童為研究對象，在辦理的健檢活動中，由專業醫護人員對前來的118位兒童施以抽血及發展篩檢的測量。兒童發展是以中文版丹佛發展篩檢測驗測量。其他與發展遲緩有關的因素包括父母親的基本資料、健康資料、居住環境及兒童的其他生理資料等，是以自製結構式問卷由訪員詢問兒童母親而獲得。此外，採集兒童的血液樣本後使用感應耦合電漿質譜儀分析血中汞、鉛、鎘、錳四種重金屬濃度。118位兒童中有完整血液和問卷資料的樣本有50位，為本研究最後的分析樣本。
研究結果發現血中鎘濃度每上升一個對數單位，兒童粗動作錯誤率增加2.56%（p = 0.010）；比起正常出生體重之兒童，低於2500克者，其粗動作、語言表現、社會適應等面向與兒童發展（全項目）的答錯率較高；母親的國籍與兒童發展間未見明顯的相關。過去研究指出，重金屬鎘的暴露會對兒童語言及注意力造成影響，而本研究發現其會影響兒童粗動作發展的表現。總之，除了重金屬鎘外，低出生體重是兒童發展問題的重要危險因子。
Background: With an estimated prevalence of developmental delay in children as high as 10% around the world, and the number in Taiwan has been increasing in recent years, it becomes an important issue and attracts the public and scholars’ attentions. Many studies have observed that some heavy metals affect children’s cognitive behavior and intelligence. However, evidence is still insufficient. Objectives: The aims of this study were to examine the effect of family, mothers’ nationality, environmental exposure and child characteristics on children’s development, and to analyze their associations with heavy metals detected in the blood sample of children. Methods: This cross-sectional study enrolled 118 children in a town located in the middle of Taiwan. This study conducted a questionnaire survey from November 2008 to January 2009 to collect data. Denver Developmental Screening Test Chinese Version (DDST-Chinese version) was to estimate the stages of children’s development. Blood levels of mercury, lead, cadmium and manganese were assayed by inductively coupled plasma mass spectrometer (ICP-MS). Results: For the increase in one unit of log transformation value of blood cadmium level, the failure rate of gross motor skill increased by 2.56% (p = 0.010). Children with low birth weight (< 2500g) had higher failure rates in the dimension of gross motor skill, language, social contact, and the all dimensions of development. Maternal nationality was not associated with the development. Conclusion: Cadmium exposure is associated with the performance of gross motor skill in children. The children of immigrant mothers are similar to native children in development. Low birth weight is a strong predictor for children’s developmental problems.
