Mill scale (ferrous metal)

Bioaccumulation: aquatic / sediment

Administrative data

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Radioactive iron absorption by gastrointestinal tract - Influence of anemia, anoxia and antecedent feeding distribution in growing dogs

Author:

Hahn PF, Bale WF, Ross JF, Balfour WM, Whipple GH

Year:

1943

Bibliographic source:

Journal of Experimental Medicine 78:169-188

Materials and methods

Test guideline

Qualifier:

no guideline required

Principles of method if other than guideline:

Scientific research paper, based on existing data and/or field measurements, following scientifically acceptable methods and procedures

Test material

Test material information

1

Reference substance name:

Iron

EC Number:

231-096-4

EC Name:

Iron

Cas Number:

7439-89-6

Molecular formula:

Fe

IUPAC Name:

Iron

Results and discussion

Bioaccumulation factor

Key result

Remarks on result:

other: no fixed BCF-value can be determined for Fe; study is used in a weight-of-evidence approach

Applicant's summary and conclusion

Conclusions:

The current vertebrate dietary iron exposure study demonstrated that intestinal adsorption/biliary excretion of iron is regulated with varying dietary intakes.

Executive summary:

Iron absorption is a function of the gastro-intestinal mucosal epithelium. The normal non-anemic dog absorbs little iron but chronic anemia due to blood loss brings about considerable absorption – perhaps 5 to 15 times normal. In general the same differences are observed in man. Sudden change from normal to severe anemia within 24 hours does not significantly increase iron absorption. As the days pass new hemoglobin is formed. The body iron stores are depleted and within 7 days iron absorption is active, even when the red cell hematocrit is rising.

Anoxemia of 50% normal oxygen concentration for 48h does not significantly enhance iron absorption. In this respect it resembles acute anemia. Ordinary doses of iron given 1 to 6 hours before radio-iron will cause some "mucosa block" – that is an intake of radio-iron less than anticipated. Many variables which modify peristalsis come into this reaction. Iron given by vein some days before the dose of radio-iron does not appear to inhibit iron absorption.

Plasma radio-iron absorption curves vary greatly. The curves may show sharp peaks in 1 to 2 hours when the iron is given in an empty stomach but after 6 hours when the radio-iron is given with food. Duration time of curves also varies widely, the plasma iron returning to normal in 6 to 12 hours.

Gastric, duodenal, or jejunal pouches all show very active absorption of iron. The plasma concentration peak may reach a maximum before the solution of iron is removed from the gastric pouch – another example of "mucosa block." Absorption and distribution of radio-iron in the body of growing pups give very suggestive experimental data. The spleen, heart, upper gastro-intestinal tract, marrow, and pancreas show more radio-iron than was expected.

The term "physiological saturation" with iron may be applied to the gastro-intestinal mucosal epithelium and explain one phase of acceptance or refusal of ingested iron. Desaturation is a matter of days not hours, whereas saturation may take place within 1 to 2 hours. It is believed that this change is a part of the complex protein metabolism of the cell.