There is widespread concern that biological machines may evolve, proliferate, and produce unexpected interactions which might alter the ecosystem. A couple of individuals vaguely referred to the 'butterfly effect' to express the concern that scientists do not sufficiently understand the ecosystems and environments with which they are dealing in order to accurately predict the outcomes of their actions. Nature behaves in unpredictable and unforeseeable ways - there is concern that something, perhaps biodiversity, will be lost if humans intervene inadvertently in the makeup of life.

The notion of 'bacteria' generally, and particularly the strains our team plans to use, have strong medical associations and are believed by many to be hazardous to health. E coli is widely understood to cause diarrhea, nausea and vomiting, whilst pseudomonas is best known for causing infections including pneumonia and swimmer's ear. Others dismissed this concern as irrational, but agreed that the ability of bacteria to 'share' genes, evolve quickly, and survive in almost any environment called for extra care by the scientists working with these organisms.

People have concerns that these will have unpredictable effects on ecosystems and that once taken these actions are difficult if not impossible to reverse. For example, synthetic organisms may outcompete their ‘natural’ counterparts and permanently damage biodiversity.

Based on vague knowledge that bacteria used in research are generally given characteristics of antibiotic resistance and that these can spread between organisms.

The public are fearful of the ability of synthetic biology to produce known/modified/new organisms designed to be harmful to humans (as demonstrated, for example, by the synthesis of viruses such as the polio virus and the pandemic Spanish Flu virus and nurtured by Hollywood dramas such as 'Outbreak').

Some of the group expressed fears about scientists 'playing God', explaining their philosophical and religious concerns about the process of creation and the nature of 'living' beings. There was significant confusion as to how exactly 'life' should be defined, where it begins and ends, and what the requisite level of complexity is. Some people vaguely expressed fears that synthetic biology will 'blur' the line between the 'artificial and natural worlds', although did not elaborate on what was meant by this nor why this would be such a negative development.

There is some concern that patenting could lead to creation of commercial monopolies and inhibit research (e.g. BRCA 1 Gene monopoly causing increase in price of testing which could potentially save lives).

Some of the group expressed worries about the fact that much of the development of synthetic biology and resulting intellectual property is likely to take place in and by extension principally benefit rich, developed nations. Particular examples of this concern which were raised included the possibility of farmers in poor countries becoming dependent on modified crop seeds controlled by large corporations which could extract whatever price they wished for the product, and the possibility of cheap alternatives for manufacture of chemicals such as antimalarial medicine (artemisinin) ensuring that local prodiction of natural equivalent products would no longer be sustained. Generally, this fear is expressed as a concern that technologies which are socially accepted on the premise that they will improve quality of life in less developed countries (golden rice and GM mosquitoes being cited as examples of such projects) may in actual fact benefit only rich Western companies and have no or even a detrimental impact on the lives of those the project was intended to help.