The organisations have warned the trusts will 'jeopardise the principles of social inclusion'.
In a letter to health minister Lord Hunt, they warn care trusts, established under the Health and Social Care Bill passing through Parliament, are too closely associated with health bodies: 'There is a significant risk that the broadly based community and social care model will lose out to a medical/clinical approach.
'Users' organisations believe this may jeopardise the principles of social inclusion and enhanced independence which lie behind social care, and undermine the invaluable contribution of services which do not equate disability and old age with ill-health.'
Councillors and social services experts demanded the Bill be amended so the care trusts are 'truly joint - equally valuing the experience and contributions of both partners'.
The LGA and ADSS raise concerns about the lack of government information on how trusts will work.
'We remain unclear about a number of critical issues of real importance to service users. Foremost among these are questions about the accountability arrangements for care trusts. Service users must be clear about who is responsible for their care.'
They warned social services funding might lose out to medical and clinical priorities.
'The funding arrangements for these new bodies also deserve much more detailed consideration. We believe that safeguards must be in place to ensure that resources for social care and community based services are protected from the wider clinical priorities of the NHS.'