Correction: Validation of the use of p-aminobenzoic acid to determine completeness of 24 h urine collections in surveys of diet and nutrition

Since publication of the original paper, the authors realised that the units of measurement in Table 1 were incorrect. These were changed from "(mg/l)" to "(% dose excreted)". Furthermore a minor typo in the title of the article was also corrected. These changes are now present in the HTML and PDF versions of the paper.