Table 1.

Total As, inorganic As (sum As⁺⁵ and As⁺³), and DMA levels for shellfish species based on individual and composite samples.

	Littleneck clam		Butter clam		Oyster		Varnish clama composite	Eastern softshell clam		Horse clamb
	Individual	Composite	Individual	Composite	Individual	Composite		Siphon	Viscera	Siphonc	Viscerad	Composite
Total As [μg/g (SD)]	3.7 (2.3)	2.2 (0.8)	4.9 (1.4)	3.2 (1.2)	1.3 (0.4)	1.2 (0.4)	1.7 (0.2)	1.2 (0.8)	1.8 (0.8)	1.4 (0.5)	1.3 (0.1)	0.9 (0.12)
Inorganic As [μg/g (SD)]	0.08 (0.03)	0.04 (0.03)	0.06 (0.01)	0.04 (0.03)	0.02 (0.02)	0.01 (0.01)	0.02 (0.01)	0.09 (0.06)	0.06 (0.03)	0.12 (0.08)	0.06 (0.08)	0.04 (0.02)
DMA [μg/g (SD)]	0.15 (0.11)	0.11 (0.05)	0.17 (0.09)	0.14 (0.05)	0.08 (0.03)	0.08 (0.02)	0.05 (0.02)	0.04 (0.02)	0.11 (0.06)	0.05 (0.02)	0.11 (0.05)	0.06 (0.02)
No.	11	16	11	17	11	11	4	8	8	16–18	15–17	3
No. in each composite	NA	10–13	NA	10–13	NA	11	11	NA	NA	NA	NA	13

NA, not available. Values shown are the sample size for each species (SD around the means) along with the number or range of individuals in each composite.

^aIndividual values were not determined for varnish clams; these clams were found only at one location.

^bComposite values are for whole immature animals; individual siphon and viscera values are from large mature animals.

^cWe used 18 animals to obtain siphon data; 2 horse clam samples were destroyed in processing for deriving total As (n = 16), while all animals were used to derive inorganic As value.

^d We used 18 animals to obtain viscera data; 2 horse clam samples were destroyed in processing for deriving total As, and one horse clam was not completely obtained in the field (n = 15). All animals were used to obtain inorganic value with the exception of the clam not completely obtained in the field (n = 17).