Table 1. Chromosomal lesion and structural chromosome alterations in exposed and non-exposed individuals detected two and six years after oil spill.

		Previous P-2y study			Follow-up P-6y study
		(2 years after oil exposure)			(6 years after oil exposure)
		Exposed	Non-exposed	P-value	Exposed	Non-exposed	P-value
Individuals studied		52	23		52	23
Total metaphases analyzed (uniform stain)		5392	2438		5346	2385
CHROMOSOME LESIONS (%)		43 (0.8)	26 (1.1)	0.3287	112 (2.1)	70 (2.9)	0.3017
	Chromatid breaks	10	6		4	4
	Chromosome breaks	13	6		27	12
	Chromatid gaps	14	10		57	35
	Chromosome gaps	6	4		24	19
Total karyotypes analyzed (G-Banded)		1377	629		1481	654
STRUCTURAL CHROMOSOME ALTERATIONS (%)		125 (9.1)	13 (2.1)	0.0007	99 (6.7)	43 (6.6)	0.9493
Balanced structural chromosome alterations		8	4		1	0
	Reciprocal translocations	6	4		1	0
	Robertsonian translocations	2	0		0	0
Unbalanced structural chromosome alterations		117	9	0.0005	98	43	0.9805
	Deletions	16	4		40	18
	Deletions and acentric fragments	4	0		5	0
	Acentric fragments	31	0		6	4
	Unbalanced translocations	10	1		10	1
	Dicentric translocations	3	0		6	0
	Dicentric translocations and deletions and acentric fragments	2	1		0	0
	Translocations and deletions	0	0		0	3
	Ring chromosomes	7	0		3	2
	Marker chromosomes	44	3		28	15

Statistical differences between exposed and non-exposed individuals are adjusted by age