Rainfall effects 2. The sanitary quality of a shellfish growing area is assessed using a variety of techniques, including bacteriological studies, hydrographic and dye studies, and sanitary reconnaissance. The assessment of sanitary quality of shellfish areas is becoming increasingly difficult. The large scale urbanization of many of our coastal areas has resulted in the proliferation of non-point pollution sources which are difficult to identify and quantify. The relationship between indicator organisms and pathogens, particularly viruses, is becoming less clear and the sanitary significance of hinterland drainage has been questioned.
Chemical contamination is of concern in many coastal areas.
It is necessary, therefore, to apply a conservative approach to growing area classification, particularly where faecal contamination has been verified but the origin is unknown, or where chemical discharges may affect shellfish growing areas.