What is the reason for thinking that the effect of heavy metals in autism will be any different in Nigeria than elsewhere in the world?

As dear Anthony said, Nigeria is the same as other countries. Do you want to follow the effect of heavy metals in childeren or you like to follow the issue in your country?

the effect of heavy metals in autism is not in my field of expertise 

Dear Doris.

You ask if there are research materials on heavy metals in children with autism in Nigeria.

I assume  that the effect of heavy metals on children with autism in Nigeria should be more or less the same as that observed in other countries. Why should it be otherwise? Is there are any psychical,  social, and so on, particularity in Nigeria that could justify that heavy metals influence children with autism differently from what happens in other countries? 

If this is not the case, your question, I lament to say, does not make much sense. Paraphrasing  C. S. Pierce, a good scientific question has to be, as it were, an "irritating question", or, in other world, a question based on an "irritating doubt". A doubt is irritating when it raises a problem whose solution would lead us to see that a given previous knowledge, hypothesis or theory is unjustifiable and even false. Unfortunately, scientists often raise "non-irritating" questions, This is particularly visible in psychology and partly justifies what the Neo-Popperian Paul Meehl (1978, Journal of Consulting and Clinical Psychology) called the "slow progress of soft psychology". To be clearer, let me give an example of a non-irritating question and doubt in my field of expertise, developmental psychology. Once, a Ph D student said me that he wanted to carry out a research so as to show and prove that Piagetian formal operations appear only after Piagetian concrete operations. My remark was the following: "How could it be otherwise?"

If formal operations are operations on concrete operations, then it is true by definition that formal operations appear only after concrete operations, and you need not to run an experiment to show that that is the case. Needless to say, psychology, among other sciences, often raises hypotheses that are true by definition, and hence, can not be falsified. In other words, we, scientists and researchers, often forget that we should be first "students of logic" and only after that "students of nature".

Consider know that you hypothesize that the influence of heavy metals on children with autism in Nigeria has to do with a particularly existing only in Nigeria. If this were the case, then your hypothesis and finding would lead us to see such an influence differently from what it used to be case.

Consider a second example. Copernicus and Galileo doubted that it was the Sun that revolved around the Earth (geocentric theory), and thought that it was the other way around (heliocentric theory). Needless to say, such way of thinking was irritating at that time. As is always the case of irritating questions, hypotheses, theories, and the like, they greatly contribute to scientific progress in any field of knowledge.

I hope that I have got your question and that my humble considerations are helpful to you.

Best regards.