Hair samples as bio-indicator

Trace element concentrations in the human body are normally determined by the analysis of blood, serum, plasma, mine or hair. Hair has an advantage over blood and urine as it accumulates elements in higher concentrations than blood and urine

258,259 collection is fast, painless and easy Frnfiier more, the analysis of hair gives long teim information on the behaviour of the elements in the body (up to 2-3 years depending on length of hair) in contrast to blood and urine which provide short-tenn infoimation Hair is also a stable biological material, which can easily be stored at room temperatm'e for a long time without a change in its composition.

A number of researchers have used hair samples to assess the nutritional and enviromnental exposme to humans. Othman and Spyrou (1980) reported increased levels of mercury (Hg) in hair samples collected from female adults and children in the Machakos district in Kenya, which are associated with the use of Hg compounds as cosmetics and lightening the colour of skin Airey (1983) analysed human hair samples for Hg in relation to fish consumption. The results showed a direct relationship between mean hair Hg and the rate of fish consumption and hence to the diet of the society Ikingura et al. (1996) reported concentrations of Hg in hair samples which were consistent to the concentration levels found in fish consumed by people living in the Lake Victoria goldfields in Tanzania Fordyce et al., (2000), indicated variations in total selenium of hair in two villages within the Enshi district

in China that coiTespond to variations in total selenium in grain, water and soil. The concentrations of elements in hair clearly supported the link between dietary Se intake and its concentrations in hair . Hair samples together with soil, water and rice determined the status of I and Se in relation to endemic goitre in Sri Lanka Menezes et al., (2004) conducted research to analyse elemental pollution from a galvanising industry using hair samples. The results showed clearly the relationship between the elements found in hair and the environmental pollution as 92% of the elements found in hair were also detected in airborne particulate matter

Hair fr'om children has also been used in several reseai'ch projects to assess their health and nutritional status. Hambidge et al., (1976) analysed Zn nutiition of preschool childi en in the Denver Head Start programme. He found lower mean Zn levels in the hair of low-income children than the hair of middle-income children.

Erten et al., (1978) found higher Zn in hair of malnoiuished childi'en than in healthy children, which he associated, with the decreased rate of hair growth in malnourished children. Lai et al., (1987) using hair samples from Indian children found a contribution of diet and enviromnental factors to the trace element concentiation in the human body Weber, et al., (1990) found significantly lower mean concenti ation of Zn in hair of malnoiuished compared to healthy children in Mexico

Reference values for elements in human hair of people from different countiies have as well been published, Iyengar et al., (1978) compiled the range of elemental composition of human tissues including hair and body fluids of ‘normal man’. Ward et al, (1987) reported the hair elemental contents of luban Bulgarian population. Batzevich (1994) reported hair elemental levels of 17 etluiic gioups from the former USSR. Oluwole et al. (1994) reported hair elemental contents of Nigerian population: At the same time, a data base of the elemental composition of human hair obtained from studies of over 25 years has been compiled in the Physics Depai*tment at the University of SuiTey as part of the database for biological and enviromnental samples So far the date base includes elemental concentrations of hair samples from Bulgaria, England, Kenya, Nigeria and Wales. This study will

produce the first data available on hair trace element concentration from children in Tanzania, which will also be included in the University of Sun*ey data base.

5,2 Sample collection

Prior to the sampling a siuwey was done to find a response, which might be received from parents when asked to donate hair samples. The survey demonstrated that people in Tanzania especially those fr'om inral areas were not going to be willing to donate hair samples particularly fr om children because of their strong superstitious beliefs. These people believed that hair could (as well as other body tissues) be employed in witchcraft to cast a bad spell on a person. This obsei-vation confirmed what was reported by Ikingura et al. (1996) who also experienced reluctance from a population in Tanzania in donating hair samples. Therefore, sample collection in this study was random and depended on the degree of trust the population had on the researcher. Samples were then collected in Dar es Salaam and Zanzibat', places that were considered as less influenced by the belief. The people in these regions were more awaie of scientific researches and the reseai'cher was better known in these places than other areas in Tanzania. The third group of samples were collected in an oiphanage/boai'ding school in Moshi district in Kilimanjaro region under the trust and permission of the headmaster.

Initially, the plan was to do all the sampling in primary schools, as it would have been easier to collect a large number of samples in a short time. Using schools however, involved asking for pennission from the ministry of education.

Unfortunately, this involved a long process, which made it impossible to get the permission on time. As the sample collection was planned to be on two months, waiting for these pennits resulted in delays. For that reason, the hair samples had to be collected from individual children’s homes, under die permission of their parents following a discussion about the objectives of the study. However, this limited the number of collected samples as the process was time consuming and taking into consideration their superstition beliefs; the paients had to be chosen carefully. Even from this small number of parents the response was not as good as expected.

Yet, a total of 141 samples of hair from children of age between 5 - 1 5 years were collected from a boarding school in Moshi, Dar es Salaam and Zanzibar. 50 samples were collected in Dar es Salaam, 45 samples in the boarding school and 46 samples in Zanzibar. Out of the 50 samples collected in Dar es Salaam, 12 samples were collected from childi'en of educated parents. These samples were from kids of the people working at the University of Dar es Salaam. 22 samples were collected fr om childi’en living in the suburban areas of Dar es Salaam whose parents have low- income, and primary school level of education and 16 samples were collected from childi’en living in Dar es Salaam city centi’e. In Zanzibar, 26 samples were collected in Zanzibar town and 20 samples from Nimgwi village 64 km fr om Zanzibar town.

About 70 to 500 mg of hair was cut using pre-cleaned stainless steel scissors as near as possible to the scalp fi’om the left side of the nape. All children or the parents (when a child was below 7 years) were interviewed at the time of sampling to obtain some general infoimation on their health. The hair samples were then cut into

1 cm long strands put into plastic bags and kept in a desiccator.