A Google search for the Material Safety Data Sheet on Harpic toilet
cleaner finds a long document, key sections of which are extracted
here.

MATERIAL SAFETY DATA SHEET
Reference: HSHARP2IN1
Creation date: 27 November 2002

PRODUCT: HARPIC TOILET BOWL CLEANER 2 IN 1

COMPANY: Reckitt Benckiser UK Ltd.
         Delta 1200, Welton Road
         Delta Business Park
         Swindon, Wiltshire, SN5 7XZ
         Tel 01793 732000
         Fax 01793 - 511572

COMPOSITION/INFORMATION ON INGREDIENTS:

The cleaning block contains the following components:
20–40% SODIUM ALKYL BENZENE SULPHONATE (Risk 38/41)
20–40% SODIUM ALPHA OLEFIN SULPHONATE (Risk 38/41)
<10% ALKYL MONOETHANOLAMIDE (Risk 41)

The hyperscent gel contains the following components:
Marine: Contains citronellol (>1%), coumarin (>1%) and eugenol (>1%)
    (Risk 43)
Lavender: Contains citronellol (<1%), coumarin (<1%), eugenol (<1%),
    geraniol (<1%), cinnamic alcohol (<1%) and hydroxycitronellol (<1%)
    (Risk 43)
Citrus: Contains geraniol (<1%), triplal (<1%), damascone alpha (<1%),
    and damascenone (<1%) (Risk 43)

Key to risks:
    R38 Irritating to skin
    R41 Risk of serious damage to eyes
    R43 May cause sensitisation by skin contact (for marine variant
        only)

Bill Burns,
Long Island, NY
http://ftldesign.com