A method based on isotope dilution headspace solid-phase microextraction, followed by gas chromatography and mass spectrometry, was developed for the determination of naphthalene in foods. Optimum method sensitivity was achieved by the addition of NaC1 in water at saturation and with the sample solution incubated at 30°C for 15 min. The method had good repeatability, with relative standard deviations of 3.5 and 1.5% at 5 and 30 ng/ml, respectively. This method was used to determine naphthalene in 159 food composite samples collected from the 2011 Canadian Total Diet Study. Naphthalene was detected in 93 (58.9%) food composite samples, mostly in products of meat and cereal, fast food, and miscellaneous foods. Among the 93 samples, only 51 (54.8%) samples were found to contain naphthalene at levels above 1 ng/g, with a maximum of 35 ng/g found in the herbs and spices composite sample. Method detection limits, estimated for each one of the food composite samples by using the lower-abundance ion m/z 127, varied considerably because of the matrix effect, ranging from as low as 0.0022 ng/g for water to as high as 16 ng/g for fatty sample, with an average of 1.6 ng/g. [ABSTRACT FROM AUTHOR]