To be 100% sure, you should check in the records some people investigating these type of spider have made. In the past I have seen those spiders have some symbols like "written" over them, you can look for those symbols in google and find what those people call "datasheets". The datasheets will tell you minimum, typical and maximum poisoning level. Be careful since, from spider to spider, there can be one that is "out" of the minimum and maximum, since those might be statistical figures and not guaranteed levels... you know, all that biology stuff is so complex.