⁶⁰Co Accident, Shanghai, China, 25 June 1990

Accident scenario

On 25 June 1990, a radiation accident occurred in a 60Co source unit in Shanghai, due to violation in operation regulation. The accident resulted in the exposure of seven individuals (A-G) to acute high dose and dose-rate whole-body external irradiation. One person felt nausea 30 min after the accident, and most of them vomited several times within 2 h after accident. All were hospitalized immediately.

The physical dose was estimated by taking account the scenario of the event, including the intensity and geometry of the source, exposure time and position of the victims. The reference dose was obtained by thermoluminescence on the exposed rubies best onto watches of two victims. In addition, simulation of dose to organs, tissues and whole body was performed using anthropomorphic phantom.

Blood samples were taken within 24 h after accident for biological dose assessment. Two individuals (A and B), who received 11-12 Gy of whole body exposure, died of extreme severe degree of bone-marrow form ARS at 25 and 90 days after exposure. Another (E) died from B-cell lymphoma 15 yrs after accident.

The victims have been followed-up every 2-3 yrs after accident for G-band karyotype analysis and FISH painting translocation analysis.

Reference

Chen, Y., Jin, C-Z., Zhang, X-Q., Ge, S-L., Zhang, Z-Y., Xu, H., Liu, X-L., Wu, D-C. and Zhen, P-K. (2009): Seventeen-year follow-up study on chromosomal aberrations in five victims accidentally exposed to several Gy of ⁶⁰Co γ-rays. Radiat. Envirn. Biophys., 48:57-65.

Chromosome aberration analysis

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	Victim	Age	ARS^*	Physical dose**	Biological dose***	No. of	No. of	Distribution of [dics+ring]
	Victim	(yrs)	ARS^*	(Gy)	(Gy)	cells^****	dic+ring	0	1	2	3	4	5	6
	A	56	Extremely severe	12.0	-
	B	53	Extremely severe	11.0	-
	C	24	Severe	5.2	5.1 (4.7-5.5)	75	149	7	21	25	11	10	1
	D	45	Severe	4.1	3.5 (3.0-3.8)	100	92	38	39	19	1	3
	E	53	Moderate	2.4	2.9 (2.5-3.2)	100	74	48	37	17	5	1
	F	20	Moderate	2.5	2.5 (2.1-2.9)	100	53	60	29	9	2
	G	33	Moderate	2.0	1.9 (1.6-2.1)	200	61	149	43	6	2
	*)	Bone marrow ARS
	**)	Physically estimated whole body dose
	***)	Doses estimated by comparing dic+r frequencies with those of in vitro dose calibration curve for Co-60 gamma-rays.
	****)	Chromosome aberration analysis at 24 h after the accident.
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Commentary at data compilation
The dose-distribution profiles by unfolding dic+r distribution. The dose distribution profiles below are not adjusted by lymphocyte survival. It is surprising that the dose distribution profiles show very homogeneous irradiation in these victims. The commentary given here is the one added at the time of data compilation, and does not necessarily reflect the conclusion of the authors.