Ortega García et al. Journal of Medical Case Reports 2011, 5:129 http://www.jmedicalcasereports.com/content/5/1/129 clinical heterogeneity in different members of a family diagnosed as autistic and others with ‘autistic traits’ sug- gest that autism is a complex neurodevelopmental disor- der in which the interactions of genetic, epigenetic and environmental influences plays a causal role [5]. The pediatric environmental history (PEH) is a critical ele- ment in clinical documentation and it is used to register the absence or presence of risk factors (RFs) associated with the occurrence of diseases such as the ASD. The PEH employs a series of basic and concise questions including genetic, genealogical and constitutional aspects that allow the clinicians to identify environmental RFs associated with disease [6]. The purpose of this case report is to illustrate the role of PEH in identifying the RFs associated with ASD and to explain the potential relationship between horsetail exposure and ASD. Case presentation We present the case of a three-year-old Caucasian girl with ASD, focusing on her PEH (Table 1). She was born after 41-weeks gestation via caesarean section and had an Apgar score of 9/10. A birth weight of 3.85 kg, head circumference of 37 cm and length at birth of 50 cm were recorded. No dyschromias or malformations were found. Our patient’s growth and karyotype were other- wise normal. She was breastfed until the age of nine weeks. By five months, she was able to hold her head steady and erect, and was able to walk on her own at 15 months of age. Our patient currently walks on her tiptoes and began this when she first started walking. On examination, our patient had normal growth and anthropometric data. Her muscle tone was moderately Table 1 Pediatric environmental history can be used to identify the absence or presence of risk factors associated with autism spectrum disorder Category Constitutional and genealogical factors Reproductive history Environmental factors Factor Sex Race/ethnicity Family history Family tree Pregnancies Hormonal therapy Socioeconomic status Home Community Medical history of ionizing radiation Legal (alcohol and tobacco) and illegal drug use Pharmaceuticals/medications Occupational exposures Hobbies Home remedy/herbal supplement use Page 2 of 5 decreased, widespread and symmetric, with normal osteotendinous nerve reflexes. Acquisition and delayed maturation of language was observed. Sensory percep- tion and attention were thought to be normal until 12 months of age. Subsequently, her parents noticed that our patient did not respond to their calls and seemed isolated with introverted behavior. Our patient was not communicative and was consistently unresponsive to the calling of her name. In addition, she did not interact with other children and presented with restricted inter- est and repetitive stereotypical behavior. Our patient did not show imitative or projective play. In terms of educa- tion, starting at two years of age she was schooled with additional support from an early learning program. Brain magnetic resonance imaging (MRI) scans appeared normal. Our patient was diagnosed with pervasive devel- opmental disorder of the autistic spectrum and moder- ate mental retardation. The 32-year-old mother and 36-year-old father lived on the second floor of a 14-year-old building in Puente Tocinos, Murcia. The mother had given birth to a healthy boy six years earlier. In the current case, the pregnancy was not planned. During the peri-concep- tional stage, the mother ingested approximately 20 to 40 g of ethanol per day, while the father ingested around 40 to 60 g of ethanol per day during the first nine days of embryonic development. The alcohol intake subse- quently decreased to 10 g/day for both parents until the 16th to 18th days of embryonic development when the parents became aware of the pregnancy and ethanol con- sumption was completely eliminated. Neither parent smoked during the pregnancy or during our patient’s first year of life, and our patient was not exposed to any other drugs. Her serology was normal, and blood test results were positive for rubella IgG antibodies. Both parents had post-high-school education. The mother was employed in the food manufacturing industry and occupational exposures during pregnancy included: phosphoric acid, alkylbenzenesulfonic acid, hydroxide and sodium hypochlorite, nitric acid, sodium hydroxide and alkyl alcohol ethoxylate. The father was employed as an auto mechanic and reported a or slight possibility that he had indirectly brought home traces of chemicals or solvents that had soiled his cloth- ing or shoes. From a year prior to conception the mother began a weight loss diet and ingested approximately 1200 mg/ day of ‘horsetail’ (Equisetum arvense) herbal remedies up to three years after birth. At conception maternal body mass index (BMI) was 31.6 kg/m2, which decreased to 30.1 kg/m2 at the end of gestation, a net loss of almost 4 kg. Throughout pregnancy, despite ade- quate caloric intake, the mother reported a daily food intake of folate (199 μg), vitamin B1 (1.18 mg), vitamin