Pentachlorophenol (PCP) and chloranil as PCDD/F sources to sewage sludge and sludge amended soils in the UK

Pentachlorophenol (PCP) and its derivatives (NaPCP and PCPL) contain PCDD/Fs (predominantly Hp-CDD/Fs and OCDD/F) as impurities. Reported concentrations of 2,3,7,8-substituted congeners in technical PCP (1000 – 3000 μg TEQ/kg) are significantly higher than those reported in PCP products such as NaPCP (84 – 510 μg TEQ/kg). PCP-based textile preservatives (particularly associated with imported cotton textiles) probably represent an important PCDD/F source to sewage sludge. Chloranil and chloranil-based dyes and pigments can contain significant levels of PCDD/F impurities as predominantly OCDD. Associated dyes and pigment contain lower PCDD/F concentrations (2 – 200 μg TEQ/kg) than pure chloranil (300 – 2900 μg TEQ/kg). The use of water-based textile dyes containing chloranil in a given catchment could represent a significant source of higher molecular weight PCDD/F congeners to the resulting sewage sludge. In addition to sewage sludge, application of other types of organic amendments (e.g. farm yard manure), paper waste sludge and textile waste could represent important sources of PCDD/Fs to agricultural soils in the UK.