就朱令頭髮分析給《國際法醫》編輯部的信(稿)

下面是俺給《國際法醫》編輯部的信稿。摘譯如下。

Ash and He (2018)文中的圖2A展示了1994年所收集的受害者一根頭髮的生長歷史。根據該圖，頭髮生長了171天；而根據第4.3節，朱女士「當年年底完全禿頂」（1994年）。根據這些信息很容易計算出：該頭髮開始生長的第一天是7月14日，而第一個峰值在第19天，即8月2日，受害者當天居家。

但是，該文圖五卻將峰值日期移至8月下旬受害者從家返校后，與圖2A相矛盾。希望通訊作者可以出來解釋一下，為什麼要不顧與圖2的矛盾而把峰值日期后延。

即使以（均值+2×標準差）來計算，也不難得出這根頭髮從8月9日開始生長的結論，而此時頭髮的含鉈量已經超過正常上限。也就是說，受害者有超過97.8%的可能於8月9日居家時中毒。

已有網友指出：這篇文章的分析還表明，兇手下毒用的是工業鉈鹽（含鉛）而非學校實驗室的鉈溶液，因為通常學校實驗室溶液是純物質。

下面是原文。

另外補充一點：清華可以查一下當年童愛軍實驗組的鉈溶液是否含鉛（這句不在信中）。

A letter to the Editorial Board of "Forensic Science International"

Regarding Richard David Ash and Min He (2018), Details of a thallium poisoning case revealed by single hair analysis
using laser ablation inductively coupled plasma mass spectrometry, Forensic Science International, Vol. 292, 224–231

A 21-year-old Chinese lady, Miss Zhu, was poisoned in 1994.

Figure 2A in Ash and He (2018) provides a scientific presentation for the growth history of a piece of hair from the victim collected in 1994.

According to Figure 2A, the hair grew for 171 days. According to Section 4.3, Miss Zhu was "completely bald at the end of that year" (1994).  It can be easily calculated that the first day of that hair started to grow on July 14. That is, based on the information given in Figure 2A and Section 4.3, "Day 1" of ZHU1995H9 (hair ID) is July 14 and Day 171 is December 31.

The first peak is 152 days from the end of the year, and August 1 is 153 days from the end of the year. Therefore the first peak should be on August 2 and the victim was at home that day.

But Figure 5 of the article moves the peak to late August after Miss Zhu returned to school from home. This contradicts with Figure 2A and Section 4.3. The second author who "conducted the interpretation" converted Figure 2A to Figure 5.
 
Even if we assume the very fast case of 7/ (0.0411 +2*0.0053)=136 (days), we still can conclude that the victim was poisoned at home. It is well known that Miss Zhu lost all her hair on December 23, 1994 when she was hospitalized. With the assumption that the hair growth period be 136 days, the hair started to grow on August 9 when she was at home. It should be noted that she was already poisoned on that day, since the amount of thallium exceeded the safety limit of 10ng/g on Day 1 of the hair [1].

In China, many people accuse Zhu's classmate Miss Sun as the "only suspect". One main reason is that Sun could "legally handle thallium solution" since Sun joined a research group in the school lab starting in September 1994. The above mentioned analyses show that it is very unlikely that Zhu was poisoned only after September 1994.

Another finding from the article by Ash and He (2018) is that Zhu was poisoned with both thallium and lead. On the internet, somebody already pointed out that this shows that the thallium must be from industrial world and could not be from a university lab. Usually, in a school lab, the substance should be pure.

In conclusion, the victim was very likely (with >97.8% chance) to be poisoned at home and the thallium must be from industrial world. The second author for some reason moved the date of the first peak after August 15 and should explain this.

Reference
[1] Queirolo F., Stegen S., Contreras-Ortega C., Ostapczuk P., Queirolo A., Paredes B. Thallium levels and bioaccumulation in environmental samples of Northern Chile: human health risks. J. Chil. Chem. Soc. 2009;54(4):464–469

附圖。

原文圖2A: