Comparison of metal levels in invertebrate detritivores and their natural diets: Concentration factors reassessed.

Concentration Factors (ppm in animal: ppm in diet) are presented for lead, zinc and cadmium in the snail Cepaea hortensis, and for lead and zinc in the woodlice Oniscus asellus and Philoscia muscorum, sampled at roadside sites. For each species such factors were found to be extremely variable, affected not only by season, and size and/or age of animals, but also by the choice of data used in estimating metal levels in the diet. It is concluded that factors other than seasonal changes in metal levels of senescent vegetation are primarily responsible for withinsite variation in the lead, zinc and cadmium concentrations of invertebrate detritivores.