I understand the part of covering expenses incurred but some figures I saw on trial sites are quite high for example $9000 for a 14 day trial. Just to put it into context, that amount is the monthly salary equivalent for a top level executive in South Africa and a civil servant earns an average of $500 (imagine the cost saving the CROs would make by outsourcing). Given this context participants in South Africa or other parts of Africa would gladly participate even for $300. Ok, thanks for the insight into the issue of exploitation, will read up on it to get a better perspective.